Clonal diversity of IL-4 and IL-13 expression in human allergen-specific T lymphocytes

The expression of IL-4 and IL-13 was analyzed in a panel of short ragweed allergen (Amb a 1)-specific T-cell clones from an allergic subject and a nonallergic individual. The T cells from the allergic subject showed a predominantly TH0 phenotype. The T cells from the nonallergic individual produced undetectable levels of IL-4 and high level of interferon-gamma, suggesting a TH1 cytokine profile. However, all T-cell clones showed significantly higher levels of IL-13 secretion than IL-4 secretion, and no quantitative correlation could be found between the levels of IL-4 and IL-13 in the clones tested. Furthermore, both cytokines showed similar kinetics of expression in antigen-induced steady-state messenger RNA. Finally, both cytokines were induced by stimulation of the cells with either ionomycin alone or with a combination of ionomycin and phorbol myristate acetate. These results demonstrate that there is a significant clonal diversity and quantitative difference in the levels of IL-4 and IL-13 expression in allergen-specific human T cells.