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In vivo absorption of aluminium-containing vaccine adjuvants using 26Al



Aluminium hydroxide (AH) and aluminium phosphate (AP) adjuvants, labelled with 26Al, were injected intramuscularly (i.m.) in New Zealand White rabbits. Blood and urine samples were collected for 28 days and analysed for 26Al using accelerator mass spectrometry to determine the absorption and elimination of AH and AP adjuvants. 26Al was present in the first blood sample (1 h) for both adjuvants. The area under the blood level curve for 28 days indicates that three times more aluminium was absorbed from AP adjuvant than AH adjuvant. The distribution profile of aluminium to tissues was the same for both adjuvants (kidney > spleen > liver > heart > lymph node > brain). This study has demonstrated that in vivo mechanisms are available to eliminate aluminium-containing adjuvants after i.m. administration. In addition, the pharmacokinetic profiles of AH and AP adjuvants are different.
Vaccine, Vol. 15, No. 12113. pp. 1314-1318, 1997
@ 1997 Elsevier Science Ltd. All rights reserved
Printed in Great Britain
PII: SO264-410X(97)00041-8 0264-410X/97 $17+0.00
In viva absorption of aluminium-
containing vaccine adjuvants using
Richard E. Flarend”, Stanley L. Hem-l-II, Joe L. White$, David Elmore”,
Mark A. Suckow§, Anita C. RudyY and Euphemie A. Dandashlit
Aluminium hydroxide (AH) and aluminium phosphate (AP) udjuvants, labelled with
‘6Al, were injected intramuscularly (i.m.) in New Zealand White rabbits. Blood and
urine samples were collected for 28 days and analysed for -“Al using accelerutor mass
ectrometly to determine the absorption and elimination of AH and AP adjuvants.
_ Al was present in the first blood sample (I h) ,for both adjutants. The area under the
blood level curve for 28 days indicates that three times more nluminium was absorbed
porn AP adjuvant than AH adjuvant. The distribution profile of aluminium to tissues
was the same for both adjuvants (kidney > spleen > liver > heart > lymph node >
brain). This study has demonstrated that in vivo mechanisms are available to eliminnte
aluminium-containing ndjuvants after i.m. administration. In addition, the pharmaco-
kinetic profiles of AH and AP adjuvants are different. 0 1997 Elsevier Science Ltd.
Keywords: adjuvant absorption. antigen desorption. “‘Al
Vaccines usually contain an antigen and an adjuvant,
which potentiates the immune response to the antigen.
The adjuvant effect of aluminium-containing
compounds was first observed in 1926’. Since that time
aluminium hydroxide adjuvant and aluminium
phosphate adjuvant have been widely used in both
human and animal vaccines. These are the only
adjuvants that are currently approved for use in human
vaccines by the United States Food and Drug Admini-
stration (FDA).
A recent study’ has shown that aluminium hydroxide
(AH) adjuvant is crystalline aluminium oxyhydroxide,
AIOOH. It has a fibrous morphology and dissolves very
slowly in simulated interstitial fluid’. Aluminium
phosphate (AP) adjuvant is amorphous aluminium
hydroxyphosphate. It has a platy morphology and
dissolves more rapidly in simulated interstitial fluid
than AH adjuvant. Interstitial fluid contains three
organic acids which have an cc-hydroxy carboxylic acid
group (citric, lactic and malic acids), and are therefore
capable of chelating aluminium3-‘. A recent in vitro
study’ showed that citrate anion was able to dissolve
*Department of Physics, Purdue University, West Lafayette,
IN 47907, USA. tDepartment of Industrial and Physical
Pharmacy, Purdue University, West Lafayette, IN 47907,
USA. *Department of Agronomy, Purdue University, West
Lafayette, IN 47907, USA. §Laboratory Animal Program,
Purdue University, West Lafayette, IN 47907, USA.
llDivision of Clinical Pharmacology, Department of
Medicine, School of Medicine, Indiana University, Indian-
apolis, IN 46202, USA. I/Author to whom all correspond-
ence should be addressed. (Received 2 August 1996;
revised version received 8 January 1997; accepted 9
January 1997)
both AH and AP adjuvants, although AP adjuvant
dissolved more rapidly.
Vaccines containing AH or AP adjuvants arc usually
administered intramuscularly. The FDA limits the
quantity of the adjuvant to no > 0.85 mg aluminium
per dose. The disposition of aluminium-containing
adjuvants after intramuscular (i.m.) administration is
not understood. This is largely because the low dose of
aluminium does not cause detectable changes in the
concentration of aluminium normally present in blood,
urine or tissues. Measurement of -“Al by accelerator
mass spectrometry (AMS)‘.” offers the first opportunity
to directly determine if aluminium-containing
adjuvants are removed from the site of injection by
dissolution in interstitial fluid. In addition, AMS allows
the absorption, distribution and elimination profiles of
aluminium-containing adjuvants to be studied and
‘“Al-containi;F AH adjuvant was prepared by adding
0.596 g, of an
‘“Al g AlC13 solution in 0.1 N HCI (170 Bq
or 0.24 pg ‘“Al g ‘) to 45 ml of 0.2 M AlCl+
Forty-five milliliters of a 0.6 N NaOH and 4 M NaCl
solution was added dropwise over 30 min to the AlCl,/
“‘AICI, solution with vigorous agitation. The precipitate
was repeatedly washed with 50 ml portions of double
distilled water (ddH:O) after centrifugation until the
supernatant was free of chloride as determined by the
absence of a precipitate when 0.1 M AgN03 was
1314 Vaccine 1997 Volume 15 Number 12/l 3
In vivo absorption of Al-containing vaccine adjuvants: R.E. Flared et al.
added. The washed precipitate was resuspended in
50 ml of ddH?O, filled into a sealed container and
placed in an 8O’C oven for 24 h. After heating, the
volume was adjusted to 57.1 ml with ddH?O. The
adjuvant suspension was autoclaved at 121°C for
20 min. A dose of 0.20 ml contains 0.85 mg Al. The
preceding procedure without the ‘“AIC13 was followed
to product an AH adjuvant for testing. The tests
showed that the AH adjuvant prepared by this
procedure exhibited the X-ray diffraction pattern and
infrared spectrum which are typical of AH adjuvant’.
“‘Al-containing AP adjuvant was prepared by
dissolving 3.7 g of alum [KAI(S0&12 H20] in enough
ddH,O to make 68 ml and adding 0.519 g of the ‘“AlCl,
solution in 0.1 N HCl (170 Bq ‘“Al g-’ or 0.24 /lg
“‘Al g ‘). A phosphate solution was prepared (0.3403 g
NaHJPO,*H,O, 0.3501 g NazHPOI and 5.5796 g NaCl)
in enough ddH:O to make 800 ml. The alum solution
was slowly added to the phosphate solution and
agitated until the solution was clear. The solution was
titrated with 1N NaOH with agitation until the pH was
7.1-7.2 to precipitate aluminium hydroxyphosphate.
The suspension was agitated for 2 h and the pH
readjusted to 7.1-7.2 with 1 N NaOH. The precipitate
was washed three times with 0.9% NaCl by centrifuga-
tion. After the third wash, the sediment was dispersed
in enough 0.9% NaCl to make 50 ml. The adjuvant
suspension was autoclaved at 121°C for 20 min. A dose
of 0.20 ml contains 0.85 mg Al. The preceding
procedure without the ‘“AlCl, was followed to produce
an AP adjuvant for testing. The tests showed that the
AP adjuvant prepared by this procedure was
amorphous by X-ray diffraction and the infrared
spectrum was typical of AP adjuvant’.
“‘Al-containing aluminium citrate was prepared by
dissolving 0.7606 g AIC13.6 Hz0 in enough ddH,O to
make 10 ml. Twenty-one microliters of the “‘AICI1
solution in 0.1 N HCl ( 170 Bq ‘“Al g or 0.24 /lg
‘“Al g -‘) was added with mixing. A citric acid solution
was prepared by dissolving 0.6620 g of citric acid in
enough ddHIO to make 10 ml. The citric acid solution
was added to the AICl$“AlCl, solution and mixed. The
pH was adjusted to 7.4 with 0.1 N NaOH.
The specific activity of the ‘“Al-labelled adjuvants
was 15.9 Bq ml for the AH adjuvant and
15.5 Bq ml for the AP adjuvant. The specific activity
of the ‘“Al-labelled aluminium citrate solution was
1.07 Bq ml-~‘. Thus, the doses contained 3.2 Bq for the
AH adjuvant (i.m.), 3.1 Bq for the AP adjuvant (i.m.)
and 0.32 Bq for the aluminium citrate solution (intra-
venous; i.v.). Calibration errors were 3-5%.
Six female New Zealand White rabbits were used to
determine the in L?\JO absorption of the ‘“Al-labelled
adjuvants. They were conditioned for 21 days before
the study and their weights were 2.5-2.8 kg at the
beginning of the study and 3.2-3.7 kg at the end of the
Two rabbits received an i.m. injection (0.2 ml of
‘“Al-labelled adjuvant followed by 0.1 ml of sterile 0.9%
NaCl to wash the syringe) of ‘“Al-labelled AH
adjuvant, two rabbits received a similar i.m. injection of
‘“Al-labelled AP adjuvant, one rabbit received an
equivalent iv. injection (0.3 ml of ‘“Al-labellcd
aluminium citrate followed by 0.1 ml of sterile 0.9%
NaCl to wash the syringe) of ‘“Al-labelled aluminium
citrate, and one rabbit received an equivalent i.m. dose
of AP adjuvant containing no ‘“Al as a cross-contami-
nation monitor. All rabbits received a total of 0.85 mg
The rabbits were killed 28 days after the injections
by sodium pentobarbital overdose. This study was
approved by the Purdue University Animal Care and
USC Committee and performed in accordance with all
federal regulations.
Sample collection
One milliliter of whole blood was collected at 0, 1, 2,
4, 6, 10. and 12 h and at 1, 2, 4, 6, 8, 12, 16 and 21 days.
Three milliliters of blood were collected at 28 days.
The samples were collected in 3 ml vials with premea-
sured ethylenediaminetetra-acetic acid and refrigerated
Urine was collected for 24 h before dosing and for
the following intervals: O-5. 5-9 and 9-24 h, l-2, 2-4,
4-6, 6-8, 11-12, 15-16. 20-21 and 27-28 days. Urine
was collected in screened pans placed under the cages.
The pans were tilled with 2 I of water at the beginning
of each collection period. At the end of the collecting
period, the pans were agitated and 40 ml aliquots were
placed in 50 ml polypropylene centrifuge tubes and
immediately refrigerated. The total volume of liquid in
the pans when the aliquot was collected was recorded.
Tissue samples were collected after the rabbits were
killed on day 28. Whole brain, heart, left kidney, liver,
mesenteric lymph node and spleen tissues were
collected and frozen in comercial plastic freezer bags.
Bone (femur) samples were also collected, but these
samples were lost during chemical preparation. The
brain sample for one of the AP-dosed rabbits was also
lost during chemical preparation.
Sample preparation
Blood and urine samples were prepared for AMS
analysis by the addition of l-100 mg - Al carrier from
AliCl (ICP 10000 p.p.m. “AI standard). The samples
were then repeatedly digested in nitric acid (70%) at
80°C in a porcelain crucible and allowed to evaporate
to dryness. After two digestions in nitric acid, the
samples were ashed at 800°C to yield A120i powder.
This AlzOJ powder was then mixed with silver powder
in a 1:3 ratio by mass and analysed by AMS.
Tissues were prepared by first dissolving the tissue
in 20-200 ml (depending on tissue size) of nitric acid
(70%) in polyethylene bottles. Aliquots of the dissolved
tissue were then prepared as described above except
that hydrogen peroxide (30%) was used as well as
nitric acid in the wet digestion.
Data analysis
Since AMS measures relative amounts of lhAl and
“Al in samples. the actual recovery percentage of
aluminium during sample preparation is irrelevant
provided that the carrier “Al is homogenized with the
-“AI native to the sample. In order to test the repro-
ducibility of the carrier addition, sample digestion, and
AMS analyses, ten samples were separately prepared in
triplicate. The results for each of these samples agreed
Vaccine 1997 Volume 15 Number 12/13 1315
In vivo absorption of Al-containing vaccine adjuvants: FE Flarend et al
within 10% (standard error of the mean) or within the
AMS precision.
Cross-contamination of ‘“Al between the animals
was monitored by the measurement of samples from
the rabbit receiving no ‘“Al dose. Data was rejected if
the ‘“Al concentration in a given sample was not at
least five times higher than the equivalent sample from
the cross-contamination monitor. Also, the “‘Al
concentration in blood, urine and tissue samples from
the cross-contamination monitor rabbit was subtracted
from the ‘“Al concentration in equivalent samples of
the other rabbits.
Cross-contamination of ‘“Al between samples during
chemical preparation was monitored with the prepara-
tion of chemistry blanks. In no case did these blanks
indicate more than a 1% cross-contamination during
chemical preparation. Chemistry blanks are samples
that are prepared alongside experimental samples.
These blanks undergo the same preparation procedure
in order to monitor any possible cross-contaminatin of
‘“Al between samples during the chemical preparation
of experimental samples.
All AMS analyses were conducted at the Purdue
Rare Isotope Measurement Laboratory, PRIME Lab”.
Although all samples were analysed for ‘hAl content,
data is reported in terms of aluminium arising from the
‘“Al-labelled adjuvants or ‘hAl-labclled aluminium
citrate. The result for the 4 h blood sample for rabbit 1
was rejected and not included in any analysis due to an
error in the recording of data for that sample.
Figure 1 shows the time profile for the aluminium
blood concentration of the four rabbits receiving the
‘“Al-labelled adjuvants. The blood level curve of both
adjuvants exhibit an absorption phase and an elimina-
tion phase, as is typical of i.m. administration. It is
noteworthy that ‘“Al was found in the blood at the first
sampling point (1 h) for both adjuvants. Thus dissolu-
tion of the adjuvants in interstitial fluid begins upon
0 200 400 600 800
elapsed time (hr)
Figure 1 Blood concentration profile after i.m. administration of
ZGAl-labelled aluminium hydroxide adjuvant: n , rabbit 1; l , rabbit
2; A, mean; or aluminium phosphate adjuvant: J, rabbit 3; ,
rabbit 4; A, mean
1316 Vaccine 1997 Volume 15 Number 12/13
administration. The aluminium concentration produced
by AH adjuvant at 1 h was similar to the concentra-
tions found from 2 to 28 days.
The mean area under the blood concentration
versus time curve (AUC) from days 0 to 28, deter-
mined using the trapezoid rule, was 1.6 x IO mg h g
for the i.v. dose of ‘“Al-labellcd aluminium citrate
(n = I): X.1 x 10 a mg h g for the “‘Al-labelled AP
adjuvant (n = 2); and 2.7 x 10 mg h g for the
“‘Al-labelled AH adjuvant (17 = 2). Thus. three times as
much aluminium was absorbed from the AP adjuvant
as from the AH adjuvant within 28 days. However,
during the first 48 h (Figure I insert), the AUC of the
AH adjuvant was 1.4 times the AUC of the AP
adjuvant. These data also indicate that 17% of the AH
adjuvant and 51%. of the AP adjuvant were absorbed
within 28 days based on the AUC of the i.v. dose of
“‘Al-labelled aluminium citrate. The blood concentra-
tion of aluminium for each of the rabbits receiving an
adjuvant had not reached a terminal elimination phase
by day 28.
Cumulative urinary excretion of aluminium (Figure
2) indicates that the body is able to eliminate the
aluminium absorbed from the adjuvants. The cumula-
tive amount of aluminium eliminated in the urine
during the 28 days of the study was 6% of the AH
adjuvant dose and 22% of the AP adjuvant dose.
Aluminium from both adjuvants was still being
excreted at a steady rate at day 28.
The pharmacokinetic parameters determined from
the blood and urine data are presented in Tut& 1.
Distribution of aluminium in tissues 28 days after
administration of AH and AP adjuvants is shown in
Figure 3. For each tissue. the concentration of
aluminium was greater in the rabbits which received
AP adjuvant. The average aluminium tissue concentra-
tion was 2.9 times greater for AP adjuvant than for AH
It is noteworthy that the aluminium concentration
produced by AH adjuvant at the first sampling point
1 .OE-1
0 200 400 600 800
elapsed time (hr)
Figure 2 Cumulative urinary excretion of aluminium after i.m.
administration of ‘“Al-labelled aluminium hydroxide adjuvant: .,
rabbit 1; l , rabbit 2; 4, mean; or aluminium phosphate adjuvant:
D, rabbit 3; -, rabbit 4; ,L, mean. Error bars of ~5% are not
In vivo absorption of Al-containing vaccine adjuvants: R.E. Flarend et al.
(1 h) was similar to the 2-28 day concentrations. This
indicates that dissolution of aluminium-containing
adjuvants in interstitial fluid begins quickly after i.m.
administration. It is surprising that the aluminium
concentrations were greater during the first 24 h for
crystalline AH adjuvant than for the amorphous AP
adjuvant. This suggests that the initial rate of dissolu-
tion from the edges of the fibrous AH adjuvant
particles is greater than from the platy AP adjuvant
The rapid appearance of aluminium in the blood
may have implications for theories regarding the
mechanism of adjuvant action of aluminium-containing
adjuvants. The most widely accepted theory is the
repository effect”‘, whereby the antigen adsorbed by
the aluminium-containing adjuvant is slowly released
after i.m. administration. The rapid appearance of
aluminium as seen in the insert of Figure I challenges
the repository mechanism as it is likely that the
adsorbed antigen would be quickly desorbed as a result
of the fast initial dissolution of the substrate.
After 2 days, the absorption rate for AP adjuvant
was considerably more than the AH adjuvant which
confirms the difference in irz vitro dissolution rates in
simulated interstitial fluid3. The blood concentration of
aluminium was fairly steady from days 2 to 28
Table 1 Pharmacokinetic parameters after i.m. injection of
“Al-containing aluminium hydroxide and aluminium phosphate
AUC for aluminium in
O-28 days % Absorbed urine after
Adjuvant (mg h g-‘) in 28 days 28 days (%)
Aluminium hydroxide
Rabbit 1 2.0 x 1om4 13 5.0
Rabbit 2 3.5x10-” 22 6.2
Average 2.7~10~~ 17 5.6
Aluminium phosphate
Rabbit 3 2.7 x 10m4 47 10
Rabbit 4 8.7 x 10m4 55 33
Average 8.1 x 10m4 51 22
1 E-4
1 E-8
Kidney Spleen
indicating a relatively constant absorption rate for each
adjuvant even 28 days after i.m. administration. No
terminal phase had been reached for the blood concen-
tration of aluminium so it is difficult to determine the
mean residence time of each adjuvant, It is clear,
however, that AP adjuvant will be eliminated before
AH adjuvant because the long term absorption rate of
the AP adjuvant is greater.
The measured increase in the plasma concentration
of aluminium from the i.v. dose was ca 600 ng ml ‘,
which is considerably more than the increase of
2 ng ml from the i.m. dose. Since it has been shown
that the pharmacokinetics of aluminium depend on the
concentration in the blood”, the pharmacokinetics of
the i.v. bolus dose were probably somewhat different
from those of the i.m. dose. Thus the AUC from the
i.v. dose may not provide a completely accurate
baseline for determining the fraction of the aluminium
absorbed from the i.m. administration of the AH and
AP adjuvants. However. this does not affect the
relative comparison of the AH and AP adjuvants.
The two rabbits which received AH adjuvant
exhibited very similar pharmacokinetic characteristics.
The blood level data for the two rabbits receiving AP
adjuvant were also very similar. However, the cumula-
tive urinary excretion of aluminium differed by a factor
of three between the two rabbits which received AP
adjuvant. This difference is probably due to intersub-
ject variability in the elimination of aluminium”. In
spite of this intersubject variation, the cumulative
urinary excretion of aluminium after 28 days in each
rabbit receiving AP adjuvant was greater than the
cumulative urinary excretion of aluminium in the
rabbits receiving AH adjuvant.
The normal pla:ma aluminium concentration in
rabbits is 30 ng ml . The maximum increase in the
plasma aluminium concentration from the 0.85 mg
aluminium doses of either adjuvant was ca 2 ng ml
This small increase would have been masked by the
aluminium background if ‘“Al-labelled adjuvants were
not used. If the same dose of these adjuvants was
administered i.m. to adult humans, an increase in the
plasma aluminium concentration of CN 0.04 ng ml-’
q @
f .*
Liver Heart L.N. Brain
Figure 3 Aluminium tissue concentration 28 days after administration of 26Al-labelled aluminium hydroxide adjuvant: ., rabbit 1; l , rabbit
2; A. mean; or aluminium phosphate adjuvant: cj, rabbit 3; ‘_, rabbit 4; a, mean. L.N., lymph node. Error bars of ~5% are not shown
Vaccine 1997 Volume 15 Number 12/13 1317
In vivo absorption of Al-containing vaccine adjuvanrs: RI. Flarend et al.
could he expected based on the larger blood volume of
humans and assuming the same rate of dissolution in
interstitial fluid. This represents a 0.8% increase in
plasma aluminium concentration based on a normal
value of 5 ng ml I’. This small change explains the
safety of aluminium-containing adjuvants and empha-
sizes the utility of AMS for studying aluminium
concentration in live.
The relative tissue distribution was the same for
both adjuvants (kidney > spleen > liver > heart >
lymph node > brain). This distribution pattern is
typical of results obtained when ‘“Al was given by other
routes of administration15. Since the concentration of
aluminium was 2.9 times greater on average in each
tissue (F&WY 3) for the rabbits which received AP
adjuvant, the tissue data is consistent with the ratio of
3.0 which was observed for the AUC of AP adjuvant
compared to AH adjuvant. Thus, the relative ‘“Al
tissue concentrations can be inferred from the ‘“Al
blood concentrations.
Since the adjuvants are being dissolved by interstitial
fluid which flows directly into the lymphatic system,
one may expect the aluminium concentration to be
quite high in the lymph tissue that was collected.
However, the i.m. doses were given in the hind quarter
where the ncarcst lymph node is difficult to isolate. For
this reason, the mesenteric lymph node. located in the
abdominal cavity, was removed. Thus the aluminium
from the dissolved adjuvants does not flow directly to
the lymph tissue that was collected and measured.
Dissolution, absorption, distribution and elimination
of aluminium-containing adjuvants after i.m. admini-
stration has been demonstrated by the use of
“‘Al-1abclled adjuvants. The two adjuvants studied
exhibited significantly different dissolution rates in
interstitial fluid which were rcflccted in different blood.
urinary excretion and tissue profiles. Human studies
using “‘Al-labelled adjuvants can be performed since
the radiation exposure to “‘Al is negligible. There was
I.6 Bq “‘Al used in each rabbit. In humans, CII 74 Bq
“‘Al would need to bc used resulting in a maximum
whole body exposure to radiation of CI~ 15 !tSv year
compared to the natural background exposure of
3000 I&V year “.
The application of AMS to the in \il>o performance
of vaccines should lead to a fuller understanding of the
mechanism of adjuvant action of aluminium-containing
adjuvants. The ability to label an aluminium-containing
compound with ‘“Al, as demonstrated in this study.
may prove useful in studying the in L~\YI absorption,
distribution, metabolism and elimination protilcs of
other aluminium-containing compounds.
This research was supported in part by the Showalter
Trust. PRIME Lab is supported by the National
Science Foundation.
Glenny, A.T., Pope, C.G.. Waddington, H. and Wallace, U. J.
The antigenic value of toxoid precipitated by potassium alum.
J. fathol. Bacterial. 1926, 29, 31-40.
Shirodkar, S.. Hutchinson, R.L., Perry, D.L., White, J.L. and
Hem, S.L. Aluminum compounds used as adjuvants in
vaccines. Pharm. Res. 1990. 7, 1282-1288.
Seeber, S.J., White, J.L. and Hem, S.L. J. Solubilization of
alummum-containing adjuvants by constituents of interstitial
fluid. Parenter. Sci. Technol. 1991, 45, 156-l 59.
Frisell. W. Human Biochemistry. McMillan, New York, 1982, p.
Bell, G.H.. Emslie-Smith. D. and Patterson, C.K. Textbook of
Physiology and Biochemistry, 9th edn. Churchill Livingston,
Edinburgh, 1976, p. 416.
Selkurt, E.E. Physiology, 4th edn. Little, Brown, Boston, 1976,
p. 537.
Flarend, R.E. and Elmore, D. Aluminium in Infant’s Health and
Nutrition. eds P. Zatta, and A.C. Alfrey. World Scientific,
London, in press.
Elmore, D. and Phillips, F.M. Accelerator mass spectrometry
for measurement of long-lived radioisotopes. Science 1987,
Elmore, D., Dep, L. and Flack, Ft. et al. The Purdue rare
isotope measurement laboratory. Nucl. Instrum. Methods
Phys. Res. 1994, 892, 65568.
World Health Organization. Immunological Adjuvants. World
Health Organization Technical Report Series No. 595, World
Health Organization, Geneva, 1976, pp. 6-8.
Wilhelm, M., Zhang, X.-J., Hafner, D. and Ohnesorge, F.K.
Single-dose toxicokinetics of aluminum in the rat. Arch.
Toxicol. 1992, 66, 700-705.
Talbot. R.J.. Newton, D., Priest, N.D.. Austin, J.G. and Day,
J.P. Intersubject variability in the metabolism of aluminum
following intravenous injection as citrate. Hum. Exp. Toxicol.
1995, 14, 595-599.
Ahn, H.-W., Fulton, B., Moxon, D. and Jeffrey, E.H. Interactive
effects of fluoride and aluminum: uptake and accumulation in
bones of rabbits administered both agents in their drinking
water. J. Toxicol. Environ. Health 1995, 44, 337-350.
Alfrey, A.C. Aluminium and Health: A Critical Review, ed. H.J.
Gitelman. Dekker, New York, 1989, pp. 101-124
Meirav. 0.. Sutton, R.A. and Fink, D. Accelerator mass
spectrometry: application to study of aluminum kinetics in the
rat. Am. J. Physiol. 1991, 260, F466-F469.
1318 Vaccine 1997 Volume 15 Number 12/l 3
... L'AH est composé de nanoparticules d'environ 2,2 nm x 4,5 nm x 10 nm qui forment spontanément des agrégats microniques ayant un aspect nano-fibreux en microscopie électronique à transmission (Eidi et al., 2015;Mold, Shardlow & Exley, 2016 questions au sujet de la réelle sécurité des adjuvants Al. Il n'existe en effet qu'une seule étude expérimentale citée comme référence pour garantir la sécurité des adjuvants Al qui analyse réellement le devenir des adjuvants dans l'organisme jusqu'à 28 jours après injection intramusculaire (IM) chez des lapins (Flarend et al., 1997) et deux analyses théoriques comparant l'accumulation d'Al issu de l'alimentation et de la vaccination chez les enfants à un seuil de sécurité extrapolé d'observations faites sur modèle animal (Keith, Jones & Chou, 2002;Mitkus et al., 2011). Notons toutefois que l'analyse de la cinétique in vivo des composés Al (adjuvants et vaccins entiers) a récemment été complétée par une étude menée chez le rat démontrant la longue persistance des adjuvants Al dans l'organisme et la translocation vers d'autres organes, ces deux paramètres étant étudiés jusqu'à 80 jours après injection (Weisser et al., 2019). ...
... I.3.3.1. Étude de l'absorption et de l'élimination de l'aluminium vaccinal (Flarend et al., 1997) Pendant longtemps les instances internationales spécialisées ont tenu pour un fait acquis que l'Al injecté par voie vaccinale était pour l'essentiel rapidement éliminé de l'organisme par voie urinaire (Eickhoff & Myers, 2002) et, encore actuellement, ce message est relayé par des sites officiels d'information à destination du grand public (Oxford Vaccine Group, 2015;, 2021). Cette affirmation prend sa source dans des études des années 90 utilisant une nouvelle technique d'étude de la toxico-cinétique de l'Al. ...
... Stanley Hem, qui semblait ignorer la capture cellulaire des adjuvants aluminiques, occasionnellement observée antérieurement à son étude pour l'AH (Erdohazi & Newman, 1971;Slater et al., 1982;Mrak, 1982), la reconnaîtra implicitement quelques années plus tard en montrant l'importance de la phagocytose dans l'effet immunologique (Morefield et al., 2005). b) Un protocole d'étude au design limité et imparfait Flarend et al., (1997) ont injecté 0,85 mg de 26 Al sous forme AH ou AP par voie IM à des lapins :  Seulement 2 lapins ont été injectés pour chaque sel d'Al étudié : ce nombre semble très insuffisant pour permettre une interprétation fiable des données sur une expérimentation biologique. En effet, les expériences montreront une forte variation interindividuelle de l'élimination urinaire d'Al après l'injection d'AP ( Figure 2). ...
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La vaccination est une avancée majeure de la médecine moderne ayant permis d’éradiquer certaines maladies et d’endiguer la propagation de nombreuses autres. Malgré une bonne tolérance par la population générale, certains individus présentent des difficultés d’élimination des particules aluminiques utilisées comme adjuvant vaccinaux. Ces patients présentent une lésion histopathologique musculaire caractéristique, biopersistante sur le long terme et composée de cellules immunitaires présentant des inclusions intracellulaires de cristaux aluminiques. Cette lésion, associée à un ensemble d'arthromyalgie, de fatigue chronique et de troubles cognitifs, est appelée myofasciite à macrophages (MFM).Les vaccins à base d’aluminium sont des particules pseudo-infectieuses gérées comme des agents pathogènes par des cellules présentatrices d'antigènes via endocytose et élimination ultérieure par l'intermédiaire de la machinerie xéno/autophagique. Par ailleurs, la littérature scientifique a montré que l’oxy-hydroxyde d'aluminium, l’un des principaux adjuvants, peut perturber la réponse autophagique. Cela conforte l’idée que l’intolérance aux adjuvants aluminiques pourrait être la conséquence d’une interaction de type « gènes x environnement » reposant sur une déficience de l’autophagie dans les cellules de l’immunité comme facteur de susceptibilité individuelle aux particules d’aluminium d’origine vaccinale.Les réponses autophagiques et inflammatoires des cellules immunitaires isolées en réponse aux particules aluminiques n’étant pas totalement caractérisées parmi la population globale. Le travail de thèse présenté dans ce manuscrit a donc eu pour premier objectif d’étudier ces réponses chez des individus sains avant de comparer les résultats avec ceux obtenus chez des individus atteint de MFM. Les données ont démontré que de nombreuses interactions entre les mécanismes d’endocytose, d’autophagie et d’inflammation sont mises en œuvre par les cellules de l’immunité en réponse à la présence de particules d’aluminium. Des expérimentations complémentaires seront nécessaires afin de caractériser finement les différentes intrications entre ces mécanismes. Cependant, certaines observations ont laissé entrevoir de subtiles variations de réponse au sein des cellules immunitaires des patients MFM exposées à des particules aluminiques. Ces cellules ont ainsi présenté un équilibre entre autophagie et endocytose penchant en faveur de l’endocytose et associé à une réponse inflammatoire réduite par rapport aux individus sains. Ces observations sont en accord avec la littérature scientifique actuelle et pourraient être principalement la conséquence plus que la cause de l’état de santé des patients MFM.Suite aux observations in vitro, des analyses exploratoires in vivo ont été menées afin de développer un modèle murin avec des perturbations de l’autophagie pour étudier l’importance de ce mécanisme dans la prise en charge et le devenir des particules aluminiques. Une étude longue a été réalisée pour tester l’efficacité d’un traitement pharmacologique (hydroxychloroquine) à perturber l’autophagie sans induire de toxicité. Nos résultats montrent que, bien qu’apparemment non toxique pour les animaux, le traitement utilisé n’a pas été en mesure de perturber l’autophagie sur le long terme. Par conséquent, l’étude de l’importance du mécanisme autophagique dans la translocation des particules d’aluminium a été réalisée en privilégiant un modèle de KO génétique. Les données ont confirmé les précédentes observations faites sans mettre en avant de rôle majeur de l’autophagie dans le déplacement des particules d’aluminium depuis le site d’injection initial, au regard du faible effectif d’animaux disponibles pour cette étude.En conclusion, ce travail a permis de mettre en évidence une prise en charge des particules aluminiques d’origine vaccinale d’une grande complexité, nécessitant une approche pluridisciplinaire pour être finement décrite.
... Finally, considering the questions of existing reference studies to determine if Al exposure through vaccines may be unsafe, one may remember that serious conceptual and methodological weaknesses have been previously described. Indeed, it has been shown that these three available toxicokinetic studies, an experimental work (Flarend et al. 1997) and two theoretical calculations (Keith et al. 2002;Mitkus et al. 2011), objectively constitute insufficient bases to guarantee the absolute safety of Al adjuvants (Masson et al. 2018). ...
... The use of 26 Al, a low-level radioactive isotope, which is distinct from the natural 27 Al, has allowed the detection of very small quantities of Al (10 À17 g) using accelerator mass spectrometry (AMS; Hem 2002). Using this technique, Flarend et al. (1997) carried out the first pharmacokinetic study of Al adjuvants in an animal model. It should be noted that this study was initially considered as a preliminary study, but was not followed by any definitive study. ...
... The remaining studies were specifically focused on adjuvant injections (see above). Berlyne et al. (1972) Aluminum toxicity in rats #2 Goto and Akama (1982) Histopathological studies of reactions in mice injected with aluminum-adsorbed tetanus toxoid #3 Flarend et al. (1997) In vivo absorption of aluminum-containing vaccine adjuvants using 26 Al #4 Valtulini et al. (2005) Aluminum hydroxide-induced granulomas in pigs #5 Verdier et al. (2005) Aluminum assay and evaluation of the local reaction at several time points after intramuscular administration of aluminum-containing vaccines in the Cynomolgus monkey #6 Authier et al. (2006) AlOH3-adjuvanted vaccine-induced macrophagic myofasciitis in rats is influenced by the genetic background #7 Petrik et al. (2007) AlOH3-adjuvanted vaccine-induced macrophagic myofasciitis in rats is influenced by the genetic background #8 Wise et al. (2008) Lack of effects on fertility and developmental toxicity of a quadrivalent HPV vaccine in Sprague-Dawley rats #9 Shaw and Petrik (2009) Aluminum hydroxide injections lead to motor deficits and motor neuron degeneration #10 Segal et al. (2011) Evaluation of the intramuscular administration of Cervarix TM vaccine on fertility, pre-and post-natal development in rats #11 Khan et al. (2013) Slow CCL2-dependent translocation of biopersistent particles from muscle to brain #12 ...
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Aluminum (Al) salts are commonly used as adjuvants in human and veterinary vaccines for almost a century. Despite this long history of use and the very large number of exposed individuals, data in the literature concerning the fate of these molecules after injection and their potential effects on the nervous system is limited. In the context of (i) an increase of exposure to Al salts through vaccination; (ii) the absence of safety values determined by health regulators; (iii) the lack of robustness of the studies used as references to officially claim Al adjuvant innocuity; (iv) the publication of several animal studies investigating Al salts clearance/biopersistence and neurotoxicity; we have examined in this review all published studies performed on animals and assessing Al adjuvants kinetics, biodistribution, and neuro-modulation since the first work of A. Glenny in the 1920s. The diversity of methodological approaches, results, and potential weaknesses of the 31 collected studies are exposed. A large range of protocols has been used, including a variety of exposure schedule and analyses methods, making comparisons between studies uneasy. Nevertheless, published data highlight that when biopersistence, translocation, or neuromodulation were assessed, they were documented whatever the different in vivo models and methods used. Moreover, the studies pointed out the crucial importance of the different Al adjuvant physicochemical properties and host genetic background on their kinetics, biodistribution, and neuro-modulatory effects. Regarding the state of the art on this key public health topic, further studies are clearly needed to determine the exact safety level of Al salts.
... In particular, (i) when injected intramuscularly, Al oxyhydroxide is assimilated at nearly 100% efficacy over time, whereas dietary absorption is less than 1% [107,142], and (ii) the adjuvant essentially remains immune cell-bound after injection. Indeed, it was shown that instead of fast elimination through urine (as previously claimed) [143], Al oxyhydroxide is subjected to remarkable retention within the body [144]. Al oxyhydroxide nanoparticles spontaneously form aggregates which after injection are promptly engulfed, remaining within phagocytic cells for long periods in both humans and animals [21,145]. ...
... Worth noting is the long-term persistence of Al oxyhydroxide aggregates in immune cells. In addition to evoking a long-lasting immune stimulation, it allows slow adjuvant translocation to remote lymphoid organs and to the brain [123,[145][146][147]. Al adjuvants can cross the BBB and may induce immunoinflammatory responses in neural tissues: this translocation has been observed in animals exposed to ABAs, Al-containing vaccines, or ABA-trackers through intramuscular, subcutaneous, or intraperitoneal injections [143,[145][146][147][156][157][158][159]. These findings prompted Khan et al. to conclude that repetitive doses of Al oxyhydroxide are "insidiously unsafe", particularly when given to newborns with an immature BBB. ...
... Finally, experimental studies focused on the biopersistence and neurotoxic effects of these compounds addressed in different animal models (mainly rodents, rabbits and sheep) showed that ABAs (mainly Al oxyhydroxide) or Al-containing vaccines (i) are capable of inducing behavioral alterations [157,[160][161][162][163][164][165][166][167][168][169], (ii) remain in the organism [143,[145][146][147]158,[170][171][172][173][174][175][176][177][178], and (iii) can leave the injection area to reach remote organs such as the nervous system [146,157,163,164,173,179,180]. Of these thirty-one studies, only six evaluated perinatal period exposure: two studies on gestational exposure on rats [181,182], three studies on newborn mice [163,167,169], and one on newborn rats [183] (for a review, see [148]). ...
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Autism spectrum disorder (ASD), schizophrenia, and bipolar disorder are genetically complex and heterogeneous neurodevelopmental disorders (NDDs) resulting from genetic factors and gene-environment (GxE) interactions for which onset occurs in early brain development. Recent progress highlights the link between ASD and (i) immunogenetics, neurodevelopment, and inflammation, and (ii) impairments of autophagy, a crucial neurodevelopmental process involved in synaptic pruning. Among various environmental factors causing risk for ASD, aluminum (Al)containing vaccines injected during critical periods have received special attention and triggered relevant scientific questions. The aim of this review is to discuss the current knowledge on the role of early inflammation, immune and autophagy dysfunction in ASD as well as preclinical studies which question Al adjuvant impacts on brain and immune maturation. We highlight the most recent breakthroughs and the lack of epidemiological, pharmacokinetic and pharmacodynamic data constituting a “scientific gap”. We propose additional research, such as genetic studies that could contribute to identify populations at genetic risk, improving diagnosis, and potentially the development of new therapeutic tools.
... A study based on IM administration of the Al26 isotope in rabbits showed a low elimination of Al26 in urine (6%) after 28 days. An unknown form of Al26 was also detected in the lymph nodes, spleen, liver, Molecules 2023, 28, 584 2 of 10 and brain [8]. Aluminum oxyhydroxide is composed of precipitates of submicron-sized nanoparticles. ...
... Aluminum oxyhydroxide is composed of precipitates of submicron-sized nanoparticles. Initially, it was believed that these precipitates remained extracellular until complete dissolution in the interstitial fluid [8]. However, it has been demonstrated that antigen-presenting cells are able to phagocyte alum nanoparticles [9] and, in so doing, to become long-lived cells [10], preventing alum dissolution [4,11,12]. ...
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Citation: Skiba, M.; Fatmi, S.; Milon, N.; Bounoure, F.; Lahiani-Skiba, M. Effect of Autoclaving on the Physicochemical Properties and Biological Activity of Aluminum Oxyhydroxide Used as an Adjuvant in Vaccines. Molecules 2023, 28, 584. Abstract: The long-term biodistribution of non-biodegradable microstructures or nanostructures used in vaccinations is widely unknown. This is the case for aluminum oxyhydroxide, the most widely used vaccine adjuvant, which is a nanocrystalline compound that spontaneously forms nanoprecipitates. Although generally well-tolerated, aluminum oxyhydroxide is detected in macrophages a long time after vaccination in individuals predisposed to the development of systemic and neurological aspects of the autoimmune (inflammatory) syndrome induced by modified adjuvant. In t present study, we established that the terminal sterilization of aluminum oxyhydroxide by autoclaving in final container vials produced measurable changes in its physicochemical properties. Moreover, we found that these changes included (1) a decreasing in the pH of aluminum oxyhydroxide solutions, (2) a reduction in the adsorption capacity of bovine serum albumin, (3) a shift in the angle of X-ray diffraction, (4) a reduction in the lattice spacing, causing the crystallization and biopersistence of modified aluminum oxyhydroxide in the macrophage, as well as in muscle and the brain.
... In vitro studies using simulated interstitial fluid and a rabbit study using isotope-labeled adjuvants indicate that AP dissolves more rapidly than AH following injection [40,41]. This is consistent with the observations that AH persists longer than AP in muscle of nonhuman primates and rats after injection of aluminum-adjuvanted vaccines [42,43]. ...
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Aluminum-based adjuvants will continue to be a key component of currently approved and next generation vaccines, including important combination vaccines. The widespread use of aluminum adjuvants is due to their excellent safety profile, which has been established through the use of hundreds of millions of doses in humans over many years. In addition, they are inexpensive, readily available, and are well known and generally accepted by regulatory agencies. Moreover, they offer a very flexible platform, to which many vaccine components can be adsorbed, enabling the preparation of liquid formulations, which typically have a long shelf life under refrigerated conditions. Nevertheless, despite their extensive use, they are perceived as relatively 'weak' vaccine adjuvants. Hence, there have been many attempts to improve their performance, which typically involves co-delivery of immune potentiators, including Toll-like receptor (TLR) agonists. This approach has allowed for the development of improved aluminum adjuvants for inclusion in licensed vaccines against HPV, HBV, and COVID-19, with others likely to follow. This review summarizes the various aluminum salts that are used in vaccines and highlights how they are prepared. We focus on the analytical challenges that remain to allowing the creation of well-characterized formulations, particularly those involving multiple antigens. In addition, we highlight how aluminum is being used to create the next generation of improved adjuvants through the adsorption and delivery of various TLR agonists.
... Antigen properties and chemical environment (pH, ionic strength, surfactant) affect the adsorption between antigen and adjuvant [71,84,85], and the surfactant increases the hydrophobic interaction between antigen-adjuvant and decreases the electrostatic adsorption between antigen-adjuvant. When rabbits were injected intramuscularly with Al 26 -labeled AH and AP, the bio-distribution sites in vivo were the same, but AP dissolved faster and had a higher concentration in the tissue fluid than AH, which was determined by the amorphous structure of AP [20]. ...
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Although hundreds of different adjuvants have been tried, aluminum-containing adjuvants are by far the most widely used currently. It is worth mentioning that although aluminum-containing adjuvants have been commonly applied in vaccine production, their acting mechanism remains not completely clear. Thus far, researchers have proposed the following mechanisms: (1) depot effect, (2) phagocytosis, (3) activation of pro-inflammatory signaling pathway NLRP3, (4) host cell DNA release, and other mechanisms of action. Having an overview on recent studies to increase our comprehension on the mechanisms by which aluminum-containing adjuvants adsorb antigens and the effects of adsorption on antigen stability and immune response has become a mainstream research trend. Aluminum-containing adjuvants can enhance immune response through a variety of molecular pathways, but there are still significant challenges in designing effective immune-stimulating vaccine delivery systems with aluminum-containing adjuvants. At present, studies on the acting mechanism of aluminum-containing adjuvants mainly focus on aluminum hydroxide adjuvants. This review will take aluminum phosphate as a representative to discuss the immune stimulation mechanism of aluminum phosphate adjuvants and the differences between aluminum phosphate adjuvants and aluminum hydroxide adjuvants, as well as the research progress on the improvement of aluminum phosphate adjuvants (including the improvement of the adjuvant formula, nano-aluminum phosphate adjuvants and a first-grade composite adjuvant containing aluminum phosphate). Based on such related knowledge, determining optimal formulation to develop effective and safe aluminium-containing adjuvants for different vaccines will become more substantiated.
... This rises an important question mark on other key factors in the case of Al builders such as solubility and release of Al 3+ ions. Except in one study [24] which was then criticized [9], this phenomenon is never considered for the two Al adjuvants in any in vivo nor in vitro study. ...
Aluminum salts have been used as adjuvants in human vaccines since 1932. The most used adjuvants are Al oxyhydroxide (AlOOH) and Al hydroxyphosphate (AlOHPO 4). Al adjuvants have different physico-chemical properties. The differences in these properties are not well documented and not considered by the Food and Drug Administration (FDA), though they can largely influence biological effects of the adjuvants which are particulate components. In this study, different physico-chemical properties including the shape, size and charge of particles have been evaluated under different conditions in three Al adjuvants containing-vaccines and two corresponding commercial adjuvants suspensions. The results showed that the two Al adjuvants have different shapes, sizes and charges but both form aggregates. In addition, a clear effect of dilution on the size of the aggregates was observed. Moreover, different sizes of Al particles were measured for both Al oxyhydroxide adjuvant alone or in the vaccine, at identical concentrations , displaying the impact of adsorbed proteins on the size of aggregates in the case of the vaccine. Taken together, this paper suggests the importance to evaluate, before any biological and especially toxicological impact study, the whole physico-chemical properties of Al particle without restricting to the sole evaluation of the injected concentration. Furthermore, any modification of these mentioned parameters during manipulation, before animal or cell exposure, should be considered. In a more global way, the fixed ''safe dose" of Al adjuvants should be specific for each type of Al adjuvant independently or for a mix of the two compounds, due to their different properties.
... Some in vivo studies have been conducted in order to evaluate the kinetics of aluminium after intramuscular injection. An experimental study performed by Flarend et al. [39] based on intramuscular injection of AlH and AlP labelled with 26 Al with a total dose of aluminium of 0.85 mg showed absorption rates of 17% for AlH and 51% for AlP within 28 days of experiments. The increased maximum serum concentration (Cmax) of 26 Al was 2 µg/L, i.e., 7% of the normal value (30 µg/L) found in rabbits. ...
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Vaccinations are one of the most important preventive tools against infectious diseases. Over time, many different types of vaccines have been developed concerning the antigen component. Adjuvants are essential elements that increase the efficacy of vaccination practises through many different actions, especially acting as carriers, depots, and stimulators of immune responses. For many years, few adjuvants have been included in vaccines, with aluminium salts being the most commonly used adjuvant. However, recent research has focused its attention on many different new compounds with effective adjuvant properties and improved safety. Modern technologies such as nanotechnologies and molecular biology have forcefully entered the production processes of both antigen and adjuvant components, thereby improving vaccine efficacy. Microparticles, emulsions, and immune stimulators are currently in the spotlight for their huge potential in vaccine production. Although studies have reported some potential side effects of vaccine adjuvants such as the recently recognised ASIA syndrome, the huge worth of vaccines remains unquestionable. Indeed, the recent COVID-19 pandemic has highlighted the importance of vaccines, especially in regard to managing future potential pandemics. In this field, research into adjuvants could play a leading role in the production of increasingly effective vaccines.
Metal homeostasis is critical to normal neurophysiological activity. Metal ions are involved in the development, metabolism, redox and neurotransmitter transmission of the central nervous system (CNS). Thus, disturbance of homeostasis (such as metal deficiency or excess) can result in serious consequences, including neurooxidative stress, excitotoxicity, neuroinflammation, and nerve cell death. The uptake, transport and metabolism of metal ions are highly regulated by ion channels. There is growing evidence that metal ion disorders and/or the dysfunction of ion channels contribute to the progression of neurodegenerative diseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Therefore, metal homeostasis-related signaling pathways are emerging as promising therapeutic targets for diverse neurological diseases. This review summarizes recent advances in the studies regarding the physiological and pathophysiological functions of metal ions and their channels, as well as their role in neurodegenerative diseases. In addition, currently available metal ion modulators and in vivo quantitative metal ion imaging methods are also discussed. Current work provides certain recommendations based on literatures and in-depth reflections to improve neurodegenerative diseases. Future studies should turn to crosstalk and interactions between different metal ions and their channels. Concomitant pharmacological interventions for two or more metal signaling pathways may offer clinical advantages in treating the neurodegenerative diseases.
Cytokines are pleiotropic soluble proteins used by immune cells to orchestrate a coordinated response against pathogens and malignancies. In cancer immunotherapy, cytokine-based drugs can be developed potentiating pro-inflammatory cytokines or blocking immunosuppressive cytokines. However, the complexity of the mechanisms of action of cytokines requires the use of biotechnological strategies to minimize systemic toxicity, while potentiating the antitumor response. Sequence mutagenesis, fusion proteins and gene therapy strategies are employed to enhance the half-life in circulation, target the desired bioactivity to the tumor microenvironment, and to optimize the therapeutic window of cytokines. In this review, we provide an overview of the different strategies currently being pursued in pre-clinical and clinical studies to make the most of cytokines for cancer immunotherapy.
Particle accelerators, such as those built for research in nuclear physics, can also be used together with magnetic and electrostatic mass analyzers to measure rare isotopes at very low abundance ratios. All molecular ions can be eliminated when accelerated to energies of millions of electron volts. Some atomic isobars can be eliminated with the use of negative ions; others can be separated at high energies by measuring their rate of energy loss in a detector. The long-lived radioisotopes (10)Be, (14)C,(26)A1, 36Cl, and (129)1 can now be measured in small natural samples having isotopic abundances in the range 10(-12) to 10(- 5) and as few as 10(5) atoms. In the past few years, research applications of accelerator mass spectrometry have been concentrated in the earth sciences (climatology, cosmochemistry, environmental chemistry, geochronology, glaciology, hydrology, igneous petrogenesis, minerals exploration, sedimentology, and volcanology), in anthropology and archeology (radiocarbon dating), and in physics (searches for exotic particles and measurement of halflives). In addition, accelerator mass spectrometry may become an important tool for the materials and biological sciences.
Purdue University has brought into operation a new NSF/NASA facility dedicated to accelerator mass spectrometry. Based on a 7.5 MV FN tandem, 10Be, 26Al, and 36Cl are being measured at a rate of 1500 samples per year. Research involves primarily 1) earth science studies using cosmogenic radionuclides produced in the atmosphere and measured in rain, groundwater, and soils, 2) Quaternary geomorphology and climatology studies using in-situ produced radionuclides, 3) planetary science studies using a wide variety of meteorites and radionuclides, and 4) biomedical tracer studies using 26Al.
The toxicokinetics of aluminum (Al) in male Wistar rats was studied after single intragastric (IG) doses of 1000 and 12,000 micrograms Al/kg and intravenous (IV) doses of 10, 100, 1000, and 12,000 micrograms Al/kg. Serial blood samples, daily samples of urine and feces as well as brain, liver, kidney, spleen, quadriceps muscle, and femur samples were collected. Al was measured by atomic absorption spectrometry. Al blood profiles after IV doses were adequately described by a two-compartment open model. Al toxicokinetics was dose dependent and appeared to plateau at 12,000 micrograms/kg. At IV doses between 10 and 1000 micrograms/kg the terminal half-life of elimination from whole blood (t1/2 beta) increased from 29.9 +/- 7.8 to 209.3 +/- 32.6 min, and the total body clearance (CL) decreased from 2.45 +/- 0.64 to 0.28 +/- 0.03 ml min-1 kg-1. Following an IV bolus of 10 and 100 micrograms/kg the administered Al was recovered completely from urine (94.4% +/- 9.9% and 98.5% +/- 3.2%). Twenty-nine days after the IV dose of 1000 micrograms/kg daily renal excretion decreased to baseline values while only 55.1% +/- 8.0% of the dose was excreted. Nineteen days after the single IV dose of 1000 micrograms/kg Al accumulated in liver (28.1 +/- 7.7 versus 1.7 +/- 0.5 micrograms/g of control rats) and spleen (72.5 +/- 21.1 versus < 0.4 microgram/g). After the single 1000 micrograms/kg IG dose no absorption of Al was detectable. The IG dose of 12,000 micrograms/kg resulted in a maximum blood Al level of 47.9 +/- 12.4 micrograms/l after 50 min.(ABSTRACT TRUNCATED AT 250 WORDS)
The solubilization of three commercially available aluminum-containing adjuvants by citrate anion was studied. Amorphous aluminum hydroxyphosphate and boehmite were both solubilized, however, amorphous aluminum hydroxyphosphate dissolved significantly faster than boehmite. The results suggest that citrate and other alpha-hydroxy carboxylate anions in the interstitial fluid are able to solubilize and thereby facilitate the excretion of aluminum from aluminum-containing adjuvants which are administered by intramuscular injection. The results also suggest that the release of antigen following administration may be significantly more rapid from an amorphous aluminum hydroxyphosphate-adjuvanted vaccine in comparison to a boehmite-adjuvanted vaccine.
The advent of accelerator mass spectrometry (AMS) now permits the ultrasensitive detection of extremely long-lived isotopes, including 14C, 26Al, and 41Ca. Until now, tracer studies of aluminum kinetics have not been possible because aluminum has only two isotopes, with half-lives of 6.5 min (29Al) and 7 x 10(5) yr (26Al), neither of which is suitable for conventional studies. In a novel experiment we have employed AMS to study aluminum kinetics in a normal rat and a 5/6-nephrectomized rat over a 3-wk period of intravenous injection of a tracer dose of 26Al. Kinetics were similar in the two animals; approximately 75% of intravenously injected tracer 26Al was excreted in the urine in the first 24 h as was approximately 80% after 3 wk. Renal clearance of 26Al was approximately 0.75 body wt-1 in both rats. The results clearly demonstrate the potential of this technique for isotope tracer studies in animals as well as in humans.
The structure of nine commercially manufactured aluminum-containing adjuvants was investigated by X-ray diffraction, infrared spectroscopy, transmission electron micrography, and energy dispersive spectrometry. Seven samples which were labeled as aluminum hydroxide were identified as boehmite, a crystalline aluminum oxyhydroxide [AlO(OH)]. However, the degree of crystallinity varied between the samples. Two samples which were labeled as aluminum phosphate were found to be amorphous aluminum hydroxyphosphate. Buffer anions and sulfate anions substitute for hydroxyls in the amorphous aluminum hydroxide formed by the in situ alum precipitation method. Finally, the aluminum-containing adjuvant in diphtheria and tetanus toxoid, U.S.P., produced by three manufacturers was characterized.
1 Six healthy male volunteers received intravenous injec tions of ²⁶ Al as citrate. Accelerator mass spectrometry and γ-ray spectrometry were used to determine levels of the tracer in blood and excreta at times up to 5-6 d. 2 There was a rapid clearance from blood (mean 2% of injection remaining after 1 d) and major loss in urine (59% up to 1 d), but 27 ± 7 (s.d.)% was retained in the body at 5 d. Faecal excretion was negligible (1% up to 5 d). 3 The mean results accord with the early metabolic pat tern in the single subject of a previous, more extensive study, who had retained 4% of the injection after 3 y. Together, the two studies point to the likelihood of large inter-subject differences in the long-term accumulation of dietary aluminium by populations receiving a given level of daily intake.
Fluoride (F) and aluminum (Al), which are known to form a strong complex, are both present in finished drinking water. The effect of F and AI on one another's tissue accumulation was determined using adult male New Zealand white rabbits. Thirty-six rabbits (three per group) were given Purina Rabbit Chow and drinking water containing no F or AI, F alone (1, 4, or 50 ppm F as NaF), Al alone, (100 or 500 ppm Al as AlCl3), or a combination of F and Al, ad libitum for 10 wk. None of these treatments altered food intake or weight gain in these rabbits. However, rabbits treated with 1 ppm F and 500 ppm Al consumed significantly less water than control rabbits. The F accumulation in plasma, urine, incisors, and tibia was increased as the F addition to the drinking water increased within groups receiving a single concentration of Al. In contrast, F accumulation in plasma, urine, incisors, and tibia decreased as the Al concentration increased within groups receiving a single F concentration, indicative of decreased intestinal absorption. Importantly, Al levels in tibia were significantly increased by the addition of F to the drinking water, even in animals receiving no Al in their drinking water. The effect of F on Al accumulation in bone was confirmed by our evaluating Al levels in sterna harvested from rats treated with 0 or 79 ppm F (as NaF in the drinking water) in a study conducted by the National Toxicology Program (Bucher et al., 1991). Therefore, some of the osteotoxicity seemingly associated with high F levels in bone may be due to the accumulation of Al or an Al-F complex.