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ABSTRACT: Penicillins are beta-lactam antibiotics able to generate several antigenic determinants that are recognized by the immune system. To study the differences in the antigen binding site of two monoclonal antibodies (Mab) specific to amoxicillin, polyclonal rabbit anti-idiotypic antibodies were produced. One Mab, AO3.2 (IgG2a), specific to a structure formed by the acyl-side chain structure and a part of the nuclear region of amoxicillin. The second one, AO6.2 (IgE), is specific to the side chain of amoxicillin, although it also recognizes the side chain of other penicillins (penicillin G and ampicillin). These antibodies were used to immunize rabbits in order to produce polyclonal anti-idiotypic antibodies, which were purified in several steps by affinity chromatography. The specificity and cross-reactivity studies were made by ELISA and ELISA inhibition. The results suggest that the anti-Id antibodies produced are the internal image of the antigen, since the binding to their specific idiotype is blocked mainly by the original hapten (amoxicillin): in 98% of the cases with anti-id-1 (induced against AO3.2) and in 59% with anti-id-2 (induced against AO6.2). The absence of cross-reactivity of each anti-idiotypic antibody with the different Mabs specific to amoxicillin shows that the idiotypes induced by the same hapten have differences that are reflected by the nonrecognition of these anti-idiotypes. We conclude that such a small molecule as amoxicillin can present several antigenic determinants that induce a panel of antibody specificities especially directed against the side chain.
Allergy 02/2002; 57 Suppl 72:45-51. · 6.27 Impact Factor
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ABSTRACT: Latex allergens are ubiquitous, and exposure may occur from different sources in the medical environment and in daily life. The observation that subjects with latex allergy were skin test positive to major and minor determinants of penicillins led our group to carry out an investigation to try to explain these findings. A group of 20 subjects with a history of allergy to latex and with positive skin tests for, but good tolerance of, penicillins was studied. The presence of latex contaminants was studied by RAST and RAST inhibition. Sixteen of the subjects were positive to at least one of the penicillin determinants used, and 14 (87%) of these were positive to at least two determinants. Repetition of skin tests using the container without a stopper changed the skin test results to negative in almost all cases, indicating that some trace contaminants had still been present. RAST-inhibition studies showed that in all penicillin determinants there were trace amounts of latex allergens varying between 3 and 0.03 micrograms/ml. These results indicate that skin tests with penicillin in subjects allergic to latex may give false-positive results and lead to such patients being falsely diagnosed as allergic to betalactams when penicillins are stored in containers with rubber stoppers.
Allergy 03/1997; 52(2):200-4. · 6.27 Impact Factor
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ABSTRACT: The quantitation of in vitro IgE antibodies to the benzylpenicilloyl determinant (BPO) is a useful tool for evaluating suspected penicillin allergic subjects. Although many different methods have been employed, few studies have compared their diagnostic specificity and sensitivity. In this study, the sensitivity and specificity of three different radio allergo sorbent test (RAST) methods for quantitating specific IgE antibodies to the BPO determinant were compared. Thirty positive control sera (serum samples from penicillin allergic subjects with a positive clinical history and a positive penicillin skin test) and 30 negative control sera (sera from subjects with no history of penicillin allergy and negative skin tests) were tested for BPO-specific IgE antibodies by RAST using three different conjugates coupled to the solid phase: benzylpenicillin conjugated to polylysine (BPO-PLL), benzylpenicillin conjugated to human serum albumin (BPO-HSA), and benzylpenicillin conjugated to an aminospacer (BPO-SP). Receiver operator control curves (ROC analysis) were carried out by determining different cut-off points between positive and negative values. Contingence tables were constructed and sensitivity, specificity, negative predictive values (PV-), and positive predictive values (PV+) were calculated. Pearson correlation coefficients (r) and intraclass correlation coefficients (ICC) were determined and the differences between methods were compared by chi 2 analysis. Analysis of the areas defined by the ROC curves showed statistical differences among the three methods. When cut-off points for optimal sensitivity and specificity were chosen, the BPO-HSA assay was less sensitive and less specific and had a lower PV- and PV+ than the BPO-PLL and BPO-SP assays. Assessment of r and ICC indicated that the correlation was very high, but the concordance between the PLL and SP methods was higher than between the PLL and HSA or SP and HSA methods. We conclude that for quantitating IgE antibodies by RAST to the BPO determinant, BPO-SP or BPO-PLL conjugates offer advantages in sensitivity and specificity compared with BPO-HSA. These results support and extend previous in vitro studies by our group and highlight the importance of the carrier for RAST assays.
Journal of Clinical Laboratory Analysis 02/1997; 11(5):251-7. · 1.38 Impact Factor
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Allergy 01/1997; 51(12):961-3. · 6.27 Impact Factor
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ABSTRACT: The cross-reactivity between penicillins and cephalosporins can be influenced by different factors, which are not all well known. The chemical structure of the side chain may contribute to the cross-reactivity.
The study was carried out in allergic subjects who are selectively responsive to amoxicillin to determine allergenic cross-reactivity with a cephalosporin containing a side chain identical to that of amoxicillin, cefadroxil, and one containing a different side chain, cefamandole.
Allergic subjects with a selective response to amoxicillin were chosen according to the following criteria: history of an immediate allergic reaction to amoxicillin, negative skin test responses to benzylpenicilloyl and minor determinant mixture of benzylpenicillin, negative RAST response to benzylpenicilloyl, and good tolerance to benzylpenicillin and phenoxymethyl penicillin challenges. In addition, subjects had to have a positive skin test response to amoxicillin and/or positive RAST response to amoxicilloyl or, if these test results were negative, a positive challenge test response to amoxicillin. In vivo cross-reactivity to cefadroxil was assessed by giving oral cefadroxil at increasing doses from 5 to 500 mg. In vitro cross-reactivity was determined by RAST inhibition studies with amoxicilloyl RAST disks and the following monomeric conjugates in the fluid phase: amoxicillin-butylamine, cefadroxil-butylamine, and the side chain para-hydroxy-phenylglycine. Tolerance to cefamandole was determined by giving 100 mg and then 500 mg parenterally.
Twenty-one patients with a selective response to amoxicillin were included in the study. Eight subjects (38%) had a positive response to cefadroxil, and none reacted to cefamandole. In vitro RAST inhibition studies indicated that cefadroxil-butylamine monomers cross-reacted with amoxicillin butylamine and the side chain contributed relevantly to the inhibition.
These results indicate that the percentage of cross-reactivity between penicillins and cephalosporins with an identical side chain is high and that this critical part of the molecule seems to be an important contributor to these results. The value is higher than previously reported data from similar studies of non-side-chain-related cephalosporins.
Journal of Allergy and Clinical Immunology 10/1996; 98(3):671-7. · 11.00 Impact Factor
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ABSTRACT: There are instances where individuals may come into contact with penicillins without being aware of it. This non-therapeutic exposure from different sources may cause sensitization and even clinical manifestations in subjects allergic to penicillins.
To determine the capacity that inadvertent contact with penicillins may have in inducing resensitization and symptoms in patients diagnosed as allergic to penicillins who were followed over a long period of time after their initial evaluation.
A follow-up study of penicillin-allergic subjects who agreed to be regularly tested for in vitro and in vivo control of their sensitivity. Skin tests were carried out with major and minor determinants of benzylpenicillin (BPO and MDM), amoxicillin (AX), and ampicillin (AMP), and specific IgE antibodies were determined by radioallergosorbent test (RAST). A questionnaire was sent to and answered by the subjects in order to see if they experienced symptoms at any time during the follow-up period. In addition, if any unexplained symptoms occurred, a bleeper system was used to contact the allergy centre.
Seven subjects experienced anaphylactic reactions with no obvious cause. At the time of their initial allergic reaction, which was caused by exposure to prescribed penicillin, the subjects had one or more positive skin tests and/or RAST results to penicillin related reagents. However, over the following 2-4 years all their tests became negative. After reporting their unexplained reaction all seven had one or more positive skin tests and/or RAST results again and when retested 1 week later RAST measurements showed that levels of penicillin-specific IgE were maintained or increased. None of the subjects had knowingly received penicillin but the questionnaire showed that six had been exposed to it and in the seventh case exposure was likely. In two cases contact was by sexual intercourse with a partner who was receiving penicillin, three subjects had handled penicillin formulations and one had drunk from a glass previously used for giving penicillin. In the seventh case exposure could have occurred whilst in hospital for surgery, although this was not proven.
these results show that non-therapeutic exposure to penicillin can cause severe symptoms and that in vitro and in vivo testing can help in the diagnosis of such cases.
Clinical & Experimental Allergy 04/1996; 26(3):335-40. · 5.03 Impact Factor
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ABSTRACT: Previous observations indicate that in some instances subjects allergic to penicillins may experience an allergic reaction after taking the drug by one route but have good tolerance after being administered the same drug by a different route.
The purpose was to establish if cloxacillin (CLX) induced a selective response only after oral route administration in a suspected case and to study if there were differences between the oral and parenteral formulations.
Skin tests were carried out using benzylpenicillin (BP) conjugated to poly-L-lysine (BPO-PLL), minor determinant mixture of benzylpenicillin (MDM), ampicillin (AMP), amoxicillin (AX) and cloxacillin (CLX). Radioallergosorbent assay (RAST) was carried out using BPO-PLL, AX-PLL and CLX-PLL sensitized discs. In the case the skin tests and RAST were negative, a controlled challenge administering the drug by both oral and parenteral route was made. Urine samples were taken at prechallenge (basal levels) and at three periods after challenge (1-3, 3-6 and 6-9 h). Analysis of oral and parenteral formulations was made by HPLC chromatography.
All skin tests and RASTs were negative. With the challenge tests the patient tolerated parenteral BP and oral phenoxymethyl penicillin (PV) and oral and parenteral AMP up to therapeutic concentrations. Parenteral CLX (500 mg) was also tolerated but 30 min after administering 50 mg by the oral route progressive generalized erythema with pruritus, facial angioedema and tachycardia developed. Urine samples taken during the challenge tests showed an increased excretion of N-methyl histamine (N-MH) 3 h after challenge with oral CLX but no change in N-MH levels after challenge with parenteral CLX or the other penicillins, indicating that histamine was released during the allergic episode with oral CLX. HPLC analysis of the oral and parenteral CLX formulations indicated that there were no differences and that neither polymers no other contaminant materials were present.
Although the nature of the allergenic determinant involved in the induction of the reaction is not yet known, the oral route may have favoured the production of a metabolite not generated by the parenteral route.
Clinical & Experimental Allergy 02/1996; 26(1):108-11. · 5.03 Impact Factor
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ABSTRACT: Penicillins are immunogenic when administered to humans and in some instances they can also be allergenic, inducing specific IgE antibodies. Whilst the major haptenic group, the penicilloyl, is well characterised, less is known about the relative importance of the different parts of the structure for antibody binding and how this can influence the specificity of patients response. In order to investigate this further, sera from subjects who had suffered an IgE-mediated reaction to penicillins were studied using the radioallergosorbent test (RAST) and RAST inhibition. The assays employed reagents related to the penicillins causing the reaction. Using 173 sera, positive RAST results were only found with reagents based on benzyl penicillin (BP) and amoxicillin (AX). Fifty-three positive sera were selected for further studies and categorized into three groups: (A) sera only RAST positive to AX, (B) sera only positive to BP and (C) sera positive to both penicillins. RAST inhibition studies were then carried out using monomeric penicilloyl conjugates and compounds representing parts of the penicilloyl structures of BP and AX. For all three groups, monomeric penicilloyl conjugates were the most efficient inhibitors but there were differences for the other compounds. Group A sera were also inhibited by the side chain amoxicillin, whereas group B sera were poorly inhibited by all other inhibitors. Group C sera showed two patterns of inhibition, both consistent with their more cross-reactive profile.
International Archives of Allergy and Immunology 10/1995; 108(1):74-81. · 2.40 Impact Factor
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ABSTRACT: 20 subjects (8 men, 12 women) with anaphylactic or urticarial reactions after drug intake were evaluated. Tryptase (TRY) and eosinophil cationic protein (ECP) were determined in serum 2 and 24 h after the allergic episode. Histamine was determined in three sequential urine samples. Results indicated that in the group of subjects evaluated, TRY and histamine were elevated, although in not all cases for both markers. With ECP, no clear association was found either at 2 or 24 h after the allergic episode. These results suggested that mast cells participated in the adverse reactions, but a role for eosinophils could not be established. Further studies need to be undertaken to establish the participation of these cells in immediate reactions to drugs.
International Archives of Allergy and Immunology 107(1-3):160-2. · 2.40 Impact Factor
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ABSTRACT: Serum tryptase (Tryp) and eosinophil cationic protein (ECP) and urine N-methylhistamine (N-MH) were quantitated in a group of 13 subjects who had experienced immediate allergic reactions to different drugs. Results indicated that both Tryp and N-MH were involved and the levels were related to the severity of the reaction. Results of serum ECP levels failed to provide relevant information concerning the participation of eosinophils in immediate reactions to drugs.
Allergy proceedings: the official journal of regional and state allergy societies 16(3):119-22.
