Effects of interleukin 4 on an antigen-specific IgE response in vitro in murine lymphocytes.

The present study shows that interleukin 4 (IL4) can exert either stimulatory or inhibitory effects on an antigen-specific IgE response in vitro. Spleen cells from BALB/c mice that had been primed with trinitrophenyl keyhole limpet hemocyanin (TNP-KLH) were cultured with the same antigen for 2 days, washed, transferred to an antigen-free culture medium, and then cultured for 4 days. Anti-TNP IgE antibodies secreted into the medium were determined by an enzyme immunoassay developed in our laboratory. Anti-TNP IgE response was elicited by TNP-KLH in cultures of the spleen cells from mice that had been primed twice with the antigen at an interval of 3 weeks, but not in cells from animals that had received only a single injection of the antigen. When the latter cells were cultured with the antigen in the presence of mouse recombinant IL4, a considerable level of the antigen-specific IgE response was induced. In contrast, the IgE response elicited in the cells of mice that had been primed twice with the antigen was markedly down-regulated by added IL4. These observations suggest a novel function of IL4 in the regulation of IgE antibody responses.