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Epitope Mapping the Peanut Panallergen Ara h 8
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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, FAAAAI2,3, Wisdom Basera, MPH3; 1 Red Cross Children’s Hospital/University of Cape Town, Cape Town, South Africa, 2Red Cross War Memorial Children’s Hospital, Cape Town, South Africa, 3University 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.
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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, MD1, Amal H. Assa’ad, MD, FAAAAI2, Jane Khoury, PhD3, Michelle B. Lierl, MD, FAAAAI2; 1Allergy/Immunology, Children’s Mercy Hospital, Kansas City, MO, 2Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 3Cincinnati 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. x2, Wilcoxon rank-sum and correlation was used for analysis, as appropriate. RESULTS: Twenty-four peanut allergic children, mean age 6.6 years (1.416.5), 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 _0.02). There was higher in peanut allergic than non-allergic group (both p < 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 wholepeanut and egg-white IgE did not.
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Epitope Mapping the Peanut Panallergen Ara h 8 Barry K. Hurlburt, PhD1, Hsiaopo Cheng, M.S.1, Lesa Offermann2, Maksymilian Chruszcz, PhD2, Alexandra F. Santos, MD MSc3, Gideon Lack, MD3, Soheila J. Maleki, PhD1; 1USDA-ARS-SRRC, New Orleans, LA, 2University of South Carolina, Columbia, SC, 3King’s College 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 fluorescentlylabeled 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.
SATURDAY
Abstracts AB31
J ALLERGY CLIN IMMUNOL VOLUME 135, NUMBER 2
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
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, FAAAAI2,3, Wisdom Basera, MPH3; 1 Red Cross Children’s Hospital/University of Cape Town, Cape Town, South Africa, 2Red Cross War Memorial Children’s Hospital, Cape Town, South Africa, 3University 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.
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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, MD1, Amal H. Assa’ad, MD, FAAAAI2, Jane Khoury, PhD3, Michelle B. Lierl, MD, FAAAAI2; 1Allergy/Immunology, Children’s Mercy Hospital, Kansas City, MO, 2Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, 3Cincinnati 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. x2, Wilcoxon rank-sum and correlation was used for analysis, as appropriate. RESULTS: Twenty-four peanut allergic children, mean age 6.6 years (1.416.5), 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 _0.02). There was higher in peanut allergic than non-allergic group (both p < 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 wholepeanut and egg-white IgE did not.
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Epitope Mapping the Peanut Panallergen Ara h 8 Barry K. Hurlburt, PhD1, Hsiaopo Cheng, M.S.1, Lesa Offermann2, Maksymilian Chruszcz, PhD2, Alexandra F. Santos, MD MSc3, Gideon Lack, MD3, Soheila J. Maleki, PhD1; 1USDA-ARS-SRRC, New Orleans, LA, 2University of South Carolina, Columbia, SC, 3King’s College 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 fluorescentlylabeled 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.
SATURDAY
Abstracts AB31
J ALLERGY CLIN IMMUNOL VOLUME 135, NUMBER 2
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.