Therapeutic effects of preferential induction of mite-specific T helper 0 clones

The predominance of Th2 cytokine-secreting pattern in allergic asthma has been known as a cause and an accelerating factor, and Th1 suppresses these allergic phenomena, but the role of Th0 clones is obscure. Because Th1/Th2 differentiation has been determined by cytokine environment, we investigated how mite-specific helper T cells stimulated in different cytokine environments actually influenced IgE and IgG4 synthesis, which are known to be regulatory immunoglobulins for allergic response. Th0 clones, which were mainly established in the presence of IL-12, provided a great deal of help for IgG4 and IgG1 synthesis, but did not provide help for IgE synthesis, whereas Th2 clones helped IgE synthesis prominently, and IgG4 and IgG1 synthesis marginally. These characteristics of Th0 clones were also true for Th0 clones obtained from patients who were successfully treated with desensitization therapy. Furthermore, the differences in helper activity between Th0 and Th2 clones were not ascribed solely to soluble factors. These data indicate that IgE and IgG4 synthesis is differentially regulated by antigen-specific T cells, and that conversion or selection from Th2 to Th0 by the addition of IL-12 may exhibit therapeutic effects.