GRANULOCYTE-MACROPHAGE COLONY-STIMULATING FACTOR (GMCSF) CONTROLS THE PROLIFERATION AND DIFFERENTIATION OF MOUSE EPIDERMAL MELANOCYTES FROM PIGMENTED SPOTS INDUCED BY UVB

Repeated exposure of ultraviolet radiation B (UVB) on the dorsal skin of hairless mice induces the development of pigmented spots long after its cessation. The proliferation and differentiation of epidermal melanocytes in UVB-induced pigmented spots are greatly increased, and those effects are regulated by keratinocytes rather than by melanocytes. However, it remains to be resolved what factor(s) derived from keratinocytes control the proliferation and differentiation of epidermal melanocytes. In this study, primary melanoblasts (ca. 80%) and melanocytes (ca. 20%) derived from epidermal cell suspensions were cultured in a serum-free medium supplemented with granulocyte-macrophage colony-stimulating factor (GMCSF). GMCSF induced the proliferation and differentiation of melanocytes in those keratinocyte-depleted cultures. Moreover, an antibody to GMCSF inhibited the proliferation of melanoblasts and melanocytes from epidermal cell suspensions derived from the pigmented spots of UV-irradiated mice, but not from control mice. Further, the GMCSF antibody inhibited the proliferation and differentiation of melanocytes co-cultured with keratinocytes derived from UV-irradiated mice, but not from control mice. The quantity of GMCSF secreted from keratinocytes derived from the pigmented spots of UV-irradiated mice was much greater than that secreted from keratinocytes derived from control mice. Moreover, immunohistochemistry revealed the expression of GMCSF in keratinocytes derived from the pigmented spots of skin in UV-irradiated mice, but not from normal skin in control mice. These results suggest that GMCSF is one of the keratinocyte-derived factors involved in regulating the proliferation and differentiation of mouse epidermal melanocytes from UVB-induced pigmented spots.第１２回ヨーロッパ色素細胞学