- Email: [email protected]
Assessment Of a Modified Basophil Activation Test In The Diagnosis Of Peanut Allergy
Abstracts AB113
J ALLERGY CLIN IMMUNOL VOLUME 133, NUMBER 2
Prediction Of Tolerance To Food Allergens By The AllergenSpecific IgE/Total IgE Ratio Ms. Claudia Lau1, Dr. Ruchi Gupta, MD, MPH1,2, Dr. Aaron Donnell, MD3, Prof. Robert G. Hamilton, PhD, D.abmli, FAAAAI4, Dr. Kelly Newhall, MD3; 1Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 2Northwestern University Feinberg School of Medicine, Chicago, IL, 3Chicago Family Asthma & Allergy, Chicago, IL, 4Johns Hopkins University School of Medicine, Baltimore, MD. RATIONALE: Although allergists typically use allergen-specific Immunoglobulin E (IgE) levels or skin prick test wheal sizes as indicators of tolerance to a food allergen (e.g., readiness to proceed with an oral food challenge), both tests have high rates of false positive results and mislabel patients who are tolerant as allergic to the food. We sought to examine the accuracy of the ratio of allergen-specific IgE to total IgE (‘‘The Ratio’’) in predicting tolerance to a food allergen. METHODS: Medical records of food allergy patients participating in an oral food challenge at an allergy outpatient clinic were reviewed for IgE serology and oral food challenge data, which were analyzed for associations using Mann-Whitney U-tests and Receiver Operator Characteristics curves. RESULTS: The Ratio for participants who failed their challenge was significantly higher than the Ratio of those who passed their challenge (1.94% vs. 1.06%, P<.001, n5195). This was mostly associated with foods for which tolerance typically is not developed, such as peanut, tree nut, shellfish, and seeds (2.58% vs. 0.88%, P<.0001, n593). Receiver Operator Characteristics curves showed the Ratio was significantly more accurate than allergen-specific IgE alone in predicting tolerance (0.69 vs. 0.55, P5.03). This finding was mostly associated with foods for which tolerance typically is not developed (0.81 vs. 0.54, P<.01). CONCLUSIONS: The Ratio is more accurate than allergen-specific IgE alone in predicting tolerance to foods for which tolerance typically is not developed. The Ratio may be a useful indicator to identify patients most likely to pass an oral food challenge.
395
T Regulatory Cells and Food Specific Responses In Peanut and Egg Allergic Children Nashmia Qamar, DO, Anna B. Fishbein, Kristin A. Erickson, Miao Cai, MS, Christine Szychlinski, MS, APN, CPNP, Ramsay L. Fuleihan, MD, Dr. Anne Marie Singh, MD; Division of Allergy & Immunology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL. RATIONALE: We hypothesize that food allergic patients have higher levels of proinflammatory cytokines and that control responses mediated by T regulatory cells are food specific. We report a pilot study investigating this possibility. METHODS: PBMCs from 36 children with egg allergy or without food allergy were isolated and stimulated in vitro for 48 hours with or without ovalbumin 100 mg/mL. Luminex was performed to measure expression of the cytokines IL-5, IL-10, and IL-17. Eleven additional patients with egg and/or peanut allergy, or controls had flow cytometry performed after stimulation with ovalbumin 100 mg/mL and whole peanut extract (WPE) 100 mg/mL. Linear mixed models and the Mann Whitney test were utilized for analyses. RESULTS: Children with egg allergy demonstrated increased levels of IL-5 and IL-17 expression when compared to non-food allergic children (51.23 vs 6.9 pg/mL, p<0.01, 17.54 vs 15.6 pg/mL, p<0.01). Patients without food allergy expressed higher levels of IL-10 when compared to egg allergic children (1335.2 vs 1295.65 pg/mL, p<0.01). Patients stimulated with non-relevant antigen had higher percentages of FoxP3+, IL-10 producing cells (0.69 vs 0.48%, for egg, 2.85 vs 2.21% for WPE) when compared to antigen stimulation, though this did not reach statistical significance. This finding suggests that tolerance is food specific. CONCLUSIONS: Our findings suggest that food allergy is a proinflammatory state and that antigen specific T regulatory cells are likely important in tolerance to foods.
396
Surveillance Of Persistent Nut Allergy Including The Use Of Basophil Activation Test In Pediatric Patients Dr. Ashleigh A. Olson, MD1, Kristin A. Erickson2, Miao Cai, MS2, Ms. Christine Szychlinski, APN, CPNP3, Dr. Anne Marie Singh, MD2; 1 Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 2Division of Allergy & Immunology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 3Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL. RATIONALE: 1-2% of the US population is allergic to peanuts and/or tree nuts. Specific IgE (sIgE), skin prick testing and food challenge remain the tools of current food allergy diagnosis and surveillance. We sought to characterize factors associated with persistent allergy to these foods and to evaluate the basophil activation test (BAT) as an emerging diagnostic tool in the evaluation of food allergy. METHODS: Forty-four nut allergic pediatric patients and fourteen controls enrolled in an ongoing cross-sectional study were analyzed. Historical information regarding foods avoided, preventative avoidance, accidental ingestions, sIgE and SPT were reviewed. Nine patients had blood drawn for BAT to peanut, tree nuts, and/or egg (negative control). RESULTS: When examining factors associated with persistence of food allergy, we found that peanut sIgE increased significantly in children with peanut accidental ingestion (mean pre-ingestion sIgE: 20.5, mean postingestion sIgE: 47.0, P< 0.05). Tree nut sIgE did not change. Analysis of the BAT results showed an overall sensitivity and specificity of 90% and 66% respectively. The test had a positive predictive value of 75% and negative predictive value of 88%. BAT results did not consistently reflect the corresponding specific IgE. CONCLUSIONS: This study suggests that peanut allergic patients with accidental ingestion may be less likely to develop tolerance to peanut or that development of tolerance is delayed. The BAT may prove a helpful adjunctive diagnostic and surveillance tool in food allergic patients but cannot replace food challenge.
397
Assessment Of a Modified Basophil Activation Test In The Diagnosis Of Peanut Allergy Dr. Monika Saeedian, MD; University of California, Los Angeles and Dr. Maria Garcia-Lloret, MD, UCLA. RATIONALE: The basophil activation test (BAT) is a flow cytometric test that detects basophil activation to define in vitro allergen specific inflammatory mediator release. Our objective is to establish a modified BAT with improved sensitivity for defining allergic reactivity to foods based on challenge results. METHODS: The presence of peanut allergy in children ages 2-16 and adults ages 17-65 will be documented by an appropriate history plus positive blood IgE or commercial skin prick testing to peanut. BAT is performed on whole blood stimulated with crude peanut extract and Ara h antigen. We utilize CD123 positive, HLA-DR negative cells to more accurately identify basophils as well as polyclonal anti-IgE antibody as the positive control for a strong activation signal. The patients then undergo oral peanut challenges. RESULTS: BAT has been performed on 10 subjects with suspected peanut allergy. After in vitro peanut challenge with crude peanut extract and Ara h antigen, the basophils from 2 peanut-allergic individuals show activation as up-regulation of CD63 expression as compared to without the addition of allergen. The basophils from 3 non-peanut allergic subjects show no activation of basophils on peanut challenge in vitro. 2 patients were nonresponders and 3 patients had failed tests due to overwhelming number of red blood cells in comparison to white blood cells. Peanut challenges are yet to be performed on these subjects. CONCLUSIONS: The BAT has potential be become an important tool in the diagnosis and management of severe food allergy by contributing to whether oral challenge can safely be undertaken.
SUNDAY
394
J ALLERGY CLIN IMMUNOL VOLUME 133, NUMBER 2
Prediction Of Tolerance To Food Allergens By The AllergenSpecific IgE/Total IgE Ratio Ms. Claudia Lau1, Dr. Ruchi Gupta, MD, MPH1,2, Dr. Aaron Donnell, MD3, Prof. Robert G. Hamilton, PhD, D.abmli, FAAAAI4, Dr. Kelly Newhall, MD3; 1Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 2Northwestern University Feinberg School of Medicine, Chicago, IL, 3Chicago Family Asthma & Allergy, Chicago, IL, 4Johns Hopkins University School of Medicine, Baltimore, MD. RATIONALE: Although allergists typically use allergen-specific Immunoglobulin E (IgE) levels or skin prick test wheal sizes as indicators of tolerance to a food allergen (e.g., readiness to proceed with an oral food challenge), both tests have high rates of false positive results and mislabel patients who are tolerant as allergic to the food. We sought to examine the accuracy of the ratio of allergen-specific IgE to total IgE (‘‘The Ratio’’) in predicting tolerance to a food allergen. METHODS: Medical records of food allergy patients participating in an oral food challenge at an allergy outpatient clinic were reviewed for IgE serology and oral food challenge data, which were analyzed for associations using Mann-Whitney U-tests and Receiver Operator Characteristics curves. RESULTS: The Ratio for participants who failed their challenge was significantly higher than the Ratio of those who passed their challenge (1.94% vs. 1.06%, P<.001, n5195). This was mostly associated with foods for which tolerance typically is not developed, such as peanut, tree nut, shellfish, and seeds (2.58% vs. 0.88%, P<.0001, n593). Receiver Operator Characteristics curves showed the Ratio was significantly more accurate than allergen-specific IgE alone in predicting tolerance (0.69 vs. 0.55, P5.03). This finding was mostly associated with foods for which tolerance typically is not developed (0.81 vs. 0.54, P<.01). CONCLUSIONS: The Ratio is more accurate than allergen-specific IgE alone in predicting tolerance to foods for which tolerance typically is not developed. The Ratio may be a useful indicator to identify patients most likely to pass an oral food challenge.
395
T Regulatory Cells and Food Specific Responses In Peanut and Egg Allergic Children Nashmia Qamar, DO, Anna B. Fishbein, Kristin A. Erickson, Miao Cai, MS, Christine Szychlinski, MS, APN, CPNP, Ramsay L. Fuleihan, MD, Dr. Anne Marie Singh, MD; Division of Allergy & Immunology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL. RATIONALE: We hypothesize that food allergic patients have higher levels of proinflammatory cytokines and that control responses mediated by T regulatory cells are food specific. We report a pilot study investigating this possibility. METHODS: PBMCs from 36 children with egg allergy or without food allergy were isolated and stimulated in vitro for 48 hours with or without ovalbumin 100 mg/mL. Luminex was performed to measure expression of the cytokines IL-5, IL-10, and IL-17. Eleven additional patients with egg and/or peanut allergy, or controls had flow cytometry performed after stimulation with ovalbumin 100 mg/mL and whole peanut extract (WPE) 100 mg/mL. Linear mixed models and the Mann Whitney test were utilized for analyses. RESULTS: Children with egg allergy demonstrated increased levels of IL-5 and IL-17 expression when compared to non-food allergic children (51.23 vs 6.9 pg/mL, p<0.01, 17.54 vs 15.6 pg/mL, p<0.01). Patients without food allergy expressed higher levels of IL-10 when compared to egg allergic children (1335.2 vs 1295.65 pg/mL, p<0.01). Patients stimulated with non-relevant antigen had higher percentages of FoxP3+, IL-10 producing cells (0.69 vs 0.48%, for egg, 2.85 vs 2.21% for WPE) when compared to antigen stimulation, though this did not reach statistical significance. This finding suggests that tolerance is food specific. CONCLUSIONS: Our findings suggest that food allergy is a proinflammatory state and that antigen specific T regulatory cells are likely important in tolerance to foods.
396
Surveillance Of Persistent Nut Allergy Including The Use Of Basophil Activation Test In Pediatric Patients Dr. Ashleigh A. Olson, MD1, Kristin A. Erickson2, Miao Cai, MS2, Ms. Christine Szychlinski, APN, CPNP3, Dr. Anne Marie Singh, MD2; 1 Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 2Division of Allergy & Immunology, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL, 3Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL. RATIONALE: 1-2% of the US population is allergic to peanuts and/or tree nuts. Specific IgE (sIgE), skin prick testing and food challenge remain the tools of current food allergy diagnosis and surveillance. We sought to characterize factors associated with persistent allergy to these foods and to evaluate the basophil activation test (BAT) as an emerging diagnostic tool in the evaluation of food allergy. METHODS: Forty-four nut allergic pediatric patients and fourteen controls enrolled in an ongoing cross-sectional study were analyzed. Historical information regarding foods avoided, preventative avoidance, accidental ingestions, sIgE and SPT were reviewed. Nine patients had blood drawn for BAT to peanut, tree nuts, and/or egg (negative control). RESULTS: When examining factors associated with persistence of food allergy, we found that peanut sIgE increased significantly in children with peanut accidental ingestion (mean pre-ingestion sIgE: 20.5, mean postingestion sIgE: 47.0, P< 0.05). Tree nut sIgE did not change. Analysis of the BAT results showed an overall sensitivity and specificity of 90% and 66% respectively. The test had a positive predictive value of 75% and negative predictive value of 88%. BAT results did not consistently reflect the corresponding specific IgE. CONCLUSIONS: This study suggests that peanut allergic patients with accidental ingestion may be less likely to develop tolerance to peanut or that development of tolerance is delayed. The BAT may prove a helpful adjunctive diagnostic and surveillance tool in food allergic patients but cannot replace food challenge.
397
Assessment Of a Modified Basophil Activation Test In The Diagnosis Of Peanut Allergy Dr. Monika Saeedian, MD; University of California, Los Angeles and Dr. Maria Garcia-Lloret, MD, UCLA. RATIONALE: The basophil activation test (BAT) is a flow cytometric test that detects basophil activation to define in vitro allergen specific inflammatory mediator release. Our objective is to establish a modified BAT with improved sensitivity for defining allergic reactivity to foods based on challenge results. METHODS: The presence of peanut allergy in children ages 2-16 and adults ages 17-65 will be documented by an appropriate history plus positive blood IgE or commercial skin prick testing to peanut. BAT is performed on whole blood stimulated with crude peanut extract and Ara h antigen. We utilize CD123 positive, HLA-DR negative cells to more accurately identify basophils as well as polyclonal anti-IgE antibody as the positive control for a strong activation signal. The patients then undergo oral peanut challenges. RESULTS: BAT has been performed on 10 subjects with suspected peanut allergy. After in vitro peanut challenge with crude peanut extract and Ara h antigen, the basophils from 2 peanut-allergic individuals show activation as up-regulation of CD63 expression as compared to without the addition of allergen. The basophils from 3 non-peanut allergic subjects show no activation of basophils on peanut challenge in vitro. 2 patients were nonresponders and 3 patients had failed tests due to overwhelming number of red blood cells in comparison to white blood cells. Peanut challenges are yet to be performed on these subjects. CONCLUSIONS: The BAT has potential be become an important tool in the diagnosis and management of severe food allergy by contributing to whether oral challenge can safely be undertaken.
SUNDAY
394