Low frequency of CD4+, but not CD8+, T cells expressing interferon-gamma is related to cow's milk allergy in infancy.

Low interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) production in peripheral blood mononuclear cells (PBMC) from patients with atopic dermatitis and food allergy have been reported previously. However, it remains unclear whether the weak cytokine production is caused by the imbalance of specific T-cell subsets or by dysregulation of T-cell function. In the present study we investigated the intracellular expression of these cytokines at a single-cell level to clarify the background of the disruption. Twelve of 27 breast-fed infants (0.1-8.8 months of age) had challenge-proven cow's milk allergy (CMA), and 15 infants were studied as a healthy control group. PBMC were stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin. The frequencies of the cells expressing intracellular IL-4, IFN-gamma, and TNF-alpha were assessed using flow cytometry. In addition, at this time-point leucocyte subsets from the milk of mothers of these infants were evaluated using light microscopy. A lower number of CD8+ T cells and the defective capability of CD4+ T cells to express IFN-gamma in infant's peripheral blood co-existed with a lower number of macrophages in their mother's milk.