Abstract

Macrophages have been known to produce monokines and to involve to the cytotoxic activity against microorganisms or tumor cells. Using murine peritoneal macrophages the effect of interferon-r(rIFN), lipopolysaccharide (LPS), 1,25 dihydroxy-vitamin D,(DHVD,) or dexamethasone alone or in combination was as- sessed on the expression of interleukin-1 and tumor necrosis factor, the production of nitric oxide (NO) and the tumoricidal activity against lymphocytic leukemic cell L1210. The results were as follows; 1) The activity of interleukin-1 was increased in the murine peritoneal macrophages treated with combination of rIFN and LPS, compared with control cells and the cells treated with each agent alone, and decreased by adding DHVD or dexamethasone. 2) The activity of tumor necrosis factor in the combined rIFN and LPS-treated cells was increased in comparison with the cells treated with each agent alone. It was not affected in the combined rIFN and LPS-treated cells by adding DHVD, while being considerably decreased by adding dexamethasone. 3) The expression of tumor necrosis factor mRNA was significantly increased in the combined rIFN and LPS-treated cells. By the addition of DHVD, the expression was a little decreased, while being considerably decreased by adding dexamethasone. 4) The production of NO was significantly increased in the cells treated with combination of rIFN and LPS, compared with the cells treated with each agent alone. By the addition of DHVD the production amount of NO in the combined rIFN and LPS-treated cells wasnt changed, however by the addition of dexamethasone the production was suppressed. 5) The tumoricidal activity of cells was significantly increased in the rlFN and LPS-treated cells, compared with the single agent-treated cells. This increased activity wasnt changed by the addition of DHVDhowever, suppressed by the addition of dexamethasone. These results indicate that DHVD slightly affects the expression of cytokine genes and the tumoricidal activity against murine lymphocytic leukemic cell LI210 in murine peritoneal macrophages, while dexamethasone considerably suppresses them.

• Keywords: DHVD, Dexamethasone, NO, L1210