Allergen-specific helper T cell response in patients with cow's milk allergy: Simultaneous analysis of proliferation and cytokine production by carboxyfluorescein succinimidyl ester dilution assay

Background: The role of antigen-specific T cells in the allergic reaction to cow's milk or in tolerance induction is not yet fully understood. Objective: This study was designed to analyse both cow's milk protein (CMP)-specific T cell proliferation and cytokine production simultaneously in children with cow's milk allergy (CMA) in comparison with subjects with various allergic backgrounds. Methods: Carboxyfluorescein succinimidyl ester was used to detect cow's milk-specific T cells by flow cytometry. The intra-cytoplasmic cytokine production of these antigen-specific T cells was also analysed. Results: Significant differences of both CMP-specific CD4⁺ cell proliferation and cytokine production between CMA and non-allergic children were observed. While the proliferative responses of children who recently outgrew CMA were not significantly different from those of patients, the patterns of cytokine production were similar to those of non-allergic children. Conclusion: These results suggest that the presence of CMP-specific T cell clones per se does not produce CMA, but that the T-helper type 2-skewed pattern of those T cells is associated with adverse reactions. Although it is not possible to distinguish between individual patients with and without CMA on the basis of CFSE assays, these results contribute to the understanding of the pathogenesis and tolerance induction of CMA.