Allergen-specific human T cell clones produce interleukin-5 upon stimulation with the Th1 cytokine interleukin-2.

CD4+ T cell clones specific for Der fII (a major allergen of the house dust mite) were established from peripheral blood mononuclear cells of atopic patients. All of the T cell clones were classified as having the Th0 phenotype, since they produced both interleukin (IL)-2 and IL-4 upon stimulation. Some of the clones produced IL-5 upon antigenic stimulation. Human recombinant IL-2 induced these T cell clones to express IL-5 mRNA and produce IL-5 protein in a dose-dependent manner. IL-2 did not induce IL-4 production, indicating a discrete signal requirement for IL-4 versus IL-5 production by T cells. Moreover, IL-5 production induced by immobilized anti-CD3 monoclonal antibody was completely suppressed by the addition of anti-IL-2 monoclonal antibody, suggesting that IL-5 production, designated as a Th2-type immune response, is dependent on IL-2, a Thl cytokine. IL-2 produced at the site of allergic inflammation may contribute to IL-5 production by T cells in vivo.