Potential interaction of interleukin-4 with endogenous cytokines in vivo.

We employed alginate-entrapped cells secreting recombinant murine interleukin-4 (IL-4) to study the effect of IL-4 on hematopoietic cells of normal mice. The most dramatic effect was registered in an increase in the neutrophils and to a lesser extent the monocytes. A small increase in the CD4+, CD8+ and B220+ populations was also observed. Serum IgE levels also increased dramatically. All of these increases could be specifically inhibited with anti-IL-4. Antibodies to granulocyte-macrophage colony-stimulating factor, IL-3 and IL-5 could also inhibit some IL-4-mediated actions suggesting an interplay between these cytokines in vivo.