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