Regulation of IgE synthesis by macrophages expressing FcE-receptors: role of interleukin 1.

Triggering rat macrophages with IgE complexes induced the production of interleukin 1-like activity (IL-1). The signal is delivered through the macrophage FcE receptor since stimulating macrophages with IgE bound to spleen cells (to avoid endocytosis) or with an anti-FcE receptor antibody linked to nonphagocytizable cells also led to IL-1 production. The molecular weight of IL-1 produced after IgE triggering is in the same range (30 kD) as previously described for rat IL-1. A positive feed-back effect of IL-1 on IgE response was suggested, as purified IL-1 was able to enhance IgE synthesis in vitro by lymphocytes from immunized animals.