Cow’s Milk Allergen Specific CD4+ T Cell Responses In Patients With Persistent Cow’s Milk Allergy

Cow’s Milk Allergen Specific CD4+ T Cell Responses In Patients With Persistent Cow’s Milk Allergy

AAAI Annual  Meeting San Diego America Sunday, March 2, 2014
Exhibit Hall B (Convention Center)’
Fatima S. Khan, MD, Nupur Bhatnagar, PhD, David Robinson, William W. Kwok, PhD
Rationale: Food allergies (FA) are increasing with approximately 4% of children affected. Cow’s milk (CM) is a common cause of fatal/ near fatal anaphylactic reactions. Understanding of CM specific CD4+ T cells responses should elucidate the pathologic mechanisms of persistent CMA.Hypothesis: Patients with persistent, IgE mediated CMA may have abnormal T cell responses to casein.

Methods: Patients 12 months and up were recruited based on their clinical history of systemic symptoms consistent with anaphylaxis to CM. Patients must also have a positive IgE by either skin prick testing or serum IgE class 3 or higher to CM. Whole blood was obtained from each subject and processed per protocol to isolate CD4+ T cells and grown in culture stimulated with CM proteins.  Subjects were HLA typed. Tetramer guided epitope mapping was conducted to identify whey and casein specific T cell epitopes and analyzed via flow cytometry. Non-allergic subjects were also recruited and similar mapping experiments were performed.

Results: All allergic subjects have Th2 type CD4+ T cells to whey protein, B lactoglobulin, and as1 casein (6/6). 83.3% (5/6) are reactive to B casein and 50% (3/6) to as2 and Kcasein. These cells are releasing IL-4 and IL-5 by cytokine analysis consistent with Th2 allergy phenotype. T cell responses in non-allergic subjects have Th1 phenotype, and were weaker in magnitude compared to allergic subjects.

Conclusions: Casein appears to be the fraction conferring lifelong CMA. Knowledge of T cell epitopes to CM consistently responsible for lifelong CMA will be useful in devising strategies to halt/reverse progression of CMA.

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