Role of interleukin-5 in local accumulation of eosinophils in mouse allergic peritonitis.

The injection of ragweed pollen extracts into the peritoneal cavity of actively immunized mice caused an accumulation of eosinophils in the cavity. We investigated the role of interleukin-5 (IL-5), one of the T-cell-derived factors, in this in vivo local accumulation. Ciclosporin, an immunosuppressant that mainly suppresses T cell functions, dose-dependently inhibited the in vivo local accumulation. Injections of the neutralizing antibody to IL-5 into the cavity decreased the number of the accumulating eosinophils. When the peritoneal cells of the immunized mice were cultured in the presence of the antigen in vitro, IL-5 activity was detected in the culture supernatant. The results indicate that IL-5 plays an important role in the in vivo local accumulation of eosinophils after an antigen challenge.