The Effects of Various Cytokines on Interleukin-6 and Interferon-α Synthesis in Human Peripheral Blood Mononuclear Cells

The effect of various recombinant cytokines on the induction of interleukin-6 (IL-6) synthesis induced in adherent and nonadherent cells of human peripheral blood mononuclear cells (PBMNC) by bacterial lipopolysaccharide (LPS) or concanavalin A (CA) was studied. The results showed that human interferon-(HuIFN)-α, -β, and γ at a concentration of 100–10,000 IU/ml enhanced the LPS-induced IL-6 production in the adherent cell fraction of PBMNC. However, in nonadherent cells, treatment with HuIFN-α or -β inhibited the CA-stimulated IL-6 production in a dose-dependent manner. Recombinant (r) IL-2 enhanced the IL-6 production of the adherent cells, while rIL-1 alone in the absence of other inducer induced IL-6 production in the nonadherent cell fraction. Other cytokines such as the recombinant tumor necrosis factor-α (rTNF-α) or rIL-6 itself did not modulate IL-6 production in human PBMNC. TNF and the interleukins studied did not affect the Sendai virus-induced IFN production in the adherent cells. In contrast, the different IFNs exerted a significant priming effect.