Calcineurin antagonists inhibit interferon-gamma production by downregulation of interleukin-18 in human mixed lymphocyte reactions

• Published in: Acta medica Okayama Vol. 54; no. 5; p. 201
• Main Authors: Kuinose, M, Iwagaki, H, Morimoto, Y, Kohka, H, Kobashi, K, Sadamori, H, Inagaki, M, Urushihara, N, Yagi, T, Tanaka, N
• Format: Journal Article
• Language: English
• Published: Japan 01-10-2000
• Subjects: Calcineurin Inhibitors; Cyclosporine - pharmacology; Down-Regulation; Humans; Immunosuppressive Agents - pharmacology; Interferon-gamma - biosynthesis; Interleukin-18 - biosynthesis; Lymphocyte Culture Test, Mixed; Tacrolimus - pharmacology
• ISSN: 0386-300X

Tacrolimus (FK-506) and cyclosporin A (CsA) are calcineurin antagonists used widely as T-cell immunosuppressants; however, their relative efficacy on the production of interleukin-18 (IL-18) remains undefined. We have examined the effects of FK-506 and CsA on the cytokine generation of human peripheral blood mononuclear cells (PBMCs) in mixed lymphocyte reaction (MLR) with lipopolysaccharide (LPS). We studied the levels of interleukin-18 (IL-18), IL-12, IL-10, IL-6, IL-2 and interferon-gamma (IFN-gamma) in the supernatant in allo-MLR by ELISA assay. Supernatant levels of IFN-gamma, IL-2, IL-6, IL-10 and IL-12 were detected 12 h after MLR and markedly increased thereafter. In contrast, production of IL-18 was detected at 12 h, reached a near maximum level at 24 h and decreased at 72 h. These results suggested that IFN-gamma production depended on IL-18, IL-12 and IL-2 in the early phase of MLR and depended mainly on IL-12 and IL-2 in the late phase. Both calcineurin antagonists inhibit the generation of IL-18, which plays a large role in allogeneic cell interactions, in macrophages and they also promote an equivalent down-regulation of T helper 1 (Th1) and Th2 responses in a concentration-dependent manner. About 90% of IFN-gamma production induced by MLR was inhibited by an anti-IL-18 antibody, showing that IL-18 can trigger IFN-gamma production in MLR. These results suggest that dual signaling consisting of antigen-driven nuclear factor of activated T cells (NFAT) activation and LPS-mediated NF-kappaB activation is crucial for IL-18 production in macrophages, and that IL-18 can trigger IFN-gamma production in T-cells by MLR.