Isotope-specific T cell factors for the IgE response.

Major research on the isotype-specific regulation of antibody responses was carried out in the IgE antibody response, and extended to the other isotypes. Because of dissociation between the IgE and IgG antibody responses, it was anticipated that each isotype may have distinct antigen-specific helper and suppressor T cells. However, current studies explain the dissociation by collaboration between antigen-specific (helper and suppressor) T cells and antigen-nonspecific, but isotype-specific T cells, which form soluble factors having the affinity for the isotype. In the IgE response, soluble factors having affinity for IgE, i.e., IgE-binding factors, are consisted of IgE-potentiating factors and IgE-suppressive factors. The main difference between the two IgE-binding factors appears to be carbohydrate moieties in the molecules. Accumulated evidence indicates that the same T cells have capacities to form both IgE-potentiating factors and IgE-suppressive factors, and suggests that the nature and biologic activities of the factors are decided in the process of the glycosylation of the same precursor molecules. Mechanisms for the regulation of the glycosylation of the factors will also be discussed in this review.