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96 Description and Outcomes of Oral Food Challenges in a Tertiary
Paediatric Allergy Clinic in South Africa
Talita A. Ferreira-van Der Watt, MBChB (UFS), FCPaeds (SA),
MMED Paeds (UStell), DCH (SA)
1
, Michael E. Levin, MBChB,
FCPaed, Dip Allergology, MMed(Paeds), PhD, EAACI allergy exam
(UEMS), Certificate Allergology, FAAAAI
2,3
, Wisdom Basera, MPH
3
;
1
Red Cross Children’s Hospital/University of Cape Town, Cape Town,
South Africa,
2
Red Cross War Memorial Children’s Hospital, Cape
Town, South Africa,
3
University of Cape Town, Cape Town, South Africa.
RATIONALE: Describe oral food challenges (OFC) at a tertiary
paediatric allergy clinic in Cape Town,South Africa: results and proportion
of subjects passing challenges despite IgE levels >internationally derived
95% positive predictive values (ID95PPVs)
1
.
METHODS: Retrospective, descriptive study of children with food
allergies undergoingOFCfrom February 2011 to April 2014 (39 months).
RESULTS: OFC’s(202) were performed on 142 children(9 months to 14
years). Egg (64), peanut (37), baked egg (29) and cow’s milk (25) were
most common. Thirty eight (18.8%) challenges were positive; 9 of 64 egg
challenges (14.1% ), 13 of 37peanut challenges (35.1% ), 5 of 29 baked egg
challenges (17.2%) and 5 of 25 cow’s milk challenges (20%).Reactions
varied from mild urticaria(23; 60.5%)to wheeze (3; 7.9%). Co-morbidities
were common; atopic dermatitis (105; 73.9%), asthma (53; 37.3%) and
allergic rhinitis (65; 45.8%). Co-morbidity correlated with positive OFC
outcome (p<0.01). OFC’s were done in 170 mixed race (MR) (84.1%)and
26 Black African (BA) (12.9%) subjects. Co-morbidity was lower in BA
subjects; asthma (3/26 vs. 65/170: p50.01); PAR/AC (7/26 vs. 79/170:
p50.06) and similar for AD (18/26 vs. 131/170: p50.38). Thirty six
percent (17/47) MR and 42.9% (3/7) BA had negative OFC’s with IgE
>ID95PPVs to egg. Fortypercent (6/15) MR and 80.0% (4/5) BA had
negative OFC’s with IgE >ID95PPVs to cow’s milk and 21.7% (5/23) MR
had negative OFC outcomes with IgE >ID95PPVs to peanut.
CONCLUSIONS: Negative challenges with IgE >ID95PPVs in BA
subjects may reflect lower manifestation of atopy.
97 What Is the Role of Component IgE Analysis By Immunocap and
Microarray Compared to Food-Specific IgE in Peanut and Egg
Allergy?
Maya K. Nanda, MD
1
, Amal H. Assa’ad, MD, FAAAAI
2
, Jane
Khoury, PhD
3
, Michelle B. Lierl, MD, FAAAAI
2
;
1
Allergy/Immunology,
Children’s Mercy Hospital, Kansas City, MO,
2
Cincinnati Children’s Hos-
pital Medical Center, Cincinnati, OH,
3
Cincinnati Children’s Hospital
Medical Center, Division of Epidemiology and Biostatistics, Cincinnati,
OH.
RATIONALE: Ara h 2 by immunoassay has been an excellent predictor of
peanut allergy, however performance of component IgE by microarray in
peanut and egg allergy is still unclear. We sought to compare component
IgE by microarray and by immunoCAP to whole food-specific IgE in
detecting clinical allergy.
METHODS: Children with peanut and egg allergy ages 1-18 years were
recruited from Children’s Hospital Allergy clinic. Allergy was defined as
failed oral food challenge (OFC) with immediate objective symptoms or as
food specific IgE >0.35 kU/L and historical immediate objective
symptoms after allergen ingestion. Non-allergic was defined as passing
OFC. Serum tests were performed by Thermofischer Scientific. x
2
,
Wilcoxon rank-sum and correlation was used for analysis, as appropriate.
RESULTS: Twenty-four peanut allergic children, mean age 6.6 years (1.4-
16.5), 67% male, 71% white and 26 egg allergic children, mean age 5.2
years (1.0-17.3), 85% male, 73% white were compared to peanut and egg
non-allergic children, respectively. Median [IQR] ara h 2 by immunoCAP
(0.7 [0.3-3.5] kU/L) and microarray (0.88 [0-2.4)] ISU) were significantly
higher in peanut allergic than non-allergic group (both p <
_0.02). There was
no difference in whole peanut IgE. Correlation between immunoCAP and
microarray ara h 2 was 0.91. Median microarray gal d 1 (0.94 [0-3.7] ISU)
was significantly higher in egg allergic than non-allergic children
(p50.02). There was no difference in immunoCAP egg white and gal
d 1 between groups.
CONCLUSIONS: Microarrayed ara h 2 and gal d 1 discriminated
between allergic and non-allergic children while immunoCAP whole-
peanut and egg-white IgE did not.
98 Epitope Mapping the Peanut Panallergen Ara h 8
Barry K. Hurlburt, PhD
1
, Hsiaopo Cheng, M.S.
1
, Lesa Offer-
mann
2
, Maksymilian Chruszcz, PhD
2
, Alexandra F. Santos, MD MSc
3
,
Gideon Lack, MD
3
, Soheila J. Maleki, PhD
1
;
1
USDA-ARS-SRRC, New
Orleans, LA,
2
University of South Carolina, Columbia, SC,
3
King’s Col-
lege London, London, United Kingdom.
RATIONALE: Ara h 8 is hypothesized to be the panallergen responsible
for oral allergy syndrome between birch pollen (Bet v 1) and peanut. We
recently determined the crystal structure of Ara h 8. In this work, we probed
microarrays of peptides with peanut allergic and peanut sensitized patient
sera for IgE and IgG4 reactivity.
METHODS: 15-mer peptides that were offset by 5 amino acids were
printed to glass. Patient sera was incubated with the slides. IgE and IgG4
binding was detected with combinations of secondary and fluorescently-
labeled tertiary antibodies. The linear epitopes identified were mapped on
the 3-D structure and compared with those of birch pollen protein Bet v 1.
RESULTS: The majority of the Ara h 8 IgE epitopes mapped in this work
align with those identified with Bet v 1. Considerably more IgG4 epitopes
than IgE epitopes were found. Peanut allergic sera were more reactive with
regard to IgE and IgG4 than peanut sensitized sera.
CONCLUSIONS: Our results support both the hypothesis that Ara h 8
could be contributing to oral allergy syndrome between birch pollen and
peanut.
J ALLERGY CLIN IMMUNOL
VOLUME 135, NUMBER 2
Abstracts AB31
SATURDAY
