Regulation of interleukin-4 production in human mononuclear cells.

Interleukin (IL)-4 is a cytokine with a broad range of effects on immune cells, however, little is known regarding the regulation of its production in freshly isolated human peripheral blood mononuclear cells (PBMC). Here we report the production of IL-4 in such cells following stimulation with monoclonal antibodies (mAb) directed against different cell surface antigens. We show that triggering via CD2 is more efficient for IL-4 production than triggering via the CD3 complex. The addition of a CD28 mAb enhances IL-4 production approximately threefold. Cell depletion experiments show that among CD2 plus CD28-stimulated PBMC the production of IL-4 is restricted to the CD8-CD45RA-T cell subpopulation. mAb interfering with the binding of IL-2 to its receptor can inhibit the production of IL-4 in CD2 plus CD28-stimulated PBMC. As IL-2 induces cell proliferation and production of interferon-gamma, but not production of IL-4, it follows that IL-2 is necessary but not sufficient for IL-4 production.