Relationships between natural T cells, atopy, IgE levels, and IL-4 production

Background: Th2 cells govern allergic disorders. Mechanisms leading to the Th2 commitment are dominated by the requirement of IL-4. A potential source of this triggering IL-4 could be the CD4+ subset of a small population of T cells, natural T (NT) cells. Indeed, this subset is involved in IgE respo nses in mice and produces promptly high amounts of IL-4 in both mice and ma n. Methods: NT cells were identified in peripheral blood by flow cytometry wit h antibodies against V2 alpha 4 and V beta 11, recognizing the T-cell recep tor specific for NT cells. Simultaneous staining with anti-CD3, anti-CD4, o r anti-CD8 antibodies was performed. The frequency of NT cells in man was s tudied according to the presence of atopy defined by the positivity of skin tests, according to total IgE levels in serum, and according to IL-4 conce ntration of whole-blood culture supernatants determined by a flow cytometer microsphere-based assay. Results: Seventy subjects were included, of whom 30 were atopic. The number of CD4+ NT cells was higher in atopics than in nonatopics (P=0.009). This number was correlated to the total IgE levels (r=0.34, P=0.03). In addition , the number of CD4+ NT cells, but also of CD8+ NT cells, was correlated to the levels of IL-4 (r=0.71, P=0.01, and r=0.6, P=0.03, respectively). Conclusions: These results show that the number of NT cells, particularly t he CD4+ subset, is related to atopy, IL-4 production, and IgE levels. There fore, this population of T cells is Likely to play a role in the Th2 commit ment initiating atopic diseases.