SYNTHESIS OF INTERLEUKIN-1-ALPHA AND INTERLEUKIN-1-BETA BY NORMAL HUMAN MELANOCYTES

Normal human melanocytes and melanoma cells have been reported to prod uce several cytokines. Previously we demonstrated that neonatal human melanocyte proliferation and tyrosinase activity are inhibited by inte rleukin-1 alpha, tumor necrosis factor-alpha, and interleukin-6. We ha ve now also shown that interleukin-1 beta induces an inhibiting effect on neonatal melanocyte tyrosinase activity with little effect on mela nocyte proliferation. We investigated the ability of neonatal and adul t human melanocytes to synthesize interleukin-1 alpha and beta. By imm unocytochemistry, using monoclonal antibodies against interleukin-1 al pha and beta, we observed that neonatal and adult melanocytes stain po sitively for both cytokines. Flow-cytometric analysis revealed that th e percentage of melanocytes positive for interleukin-1 alpha was alway s greater than that for interleukin-1 beta. The ability of neonatal an d adult melanocytes to synthesize interleukin-1 alpha and beta was fur ther confirmed using the polymerase chain reaction. These results clea rly indicate that human melanocytes synthesize interleukin-1 alpha and beta, and that these cytokines may function as autocrine and/or parac rine regulators of cells in the epidermis.