[The effects of various cell growth factors and cyclosporin A, an immunosuppressive agent, on cloned osteoblastic cell line, MC3T3-E1 cells].

Cloned MC3T3-E1 cells which have retained several osteoblast-like characteristics were derived from newborn mouse calvaria. In order to elucidate the function of osteoblasts, the effects of 1,25(OH)2D3, interleukin (IL)-1 beta, IL-3, interferon(INF)-gamma and epidermal growth factor(EGF) on the activity of alkaline phosphatase(Al-P'ase), DNA synthesis and the production of prostaglandin E2(PGE2) in MC3T3-E1 cells were studied. The influence of cyclosporin A(CSA), a potent immunosuppressive agent, was also studied. The following results were obtained: 1. 1,25(OH)2D3 increased the incorporation of [45Ca]Cl2 into matrix and accelerated the calcification of MC3T3-E1 cells. 2. Al-P'ase activity and the incorporation of [3H]-thymidine into MC3T3-E1 cells were increased by 1,25(OH)2D3 but decreased by IL-1 beta, INF-gamma, IL-3 and EGF. 3. IL-1 beta increased and INF-gamma decreased PG-E2 production by MC3T3-E1 cells. 4. CSA decreased either Al-P'ase activity or incorporation of [3H]-thymidine, and increased PG-E2 production in MC3T3-E1 cells. CSA which was simultaneously incubated with these various cell growth factors, showed a similar effect to that of CSA alone. These results suggest that cytokines produced from immune cells, could affect osteoblasts besides that of calcium regulating hormones like parathyroid hormone and 1,25(OH)2D3, implying a probability for the participation of immunocompetent cells in the regulation of bone metabolism.