Abstract: In the present study, biopsy specimens of the scalp of 20 patients were stained with antibody directed against HMB-45.20 out of 98 hair bulbs were in the early anagen phase, 63 were mature anagen, 7 were catagen and 8 showed a typical telogen feature.In 52 out of 63 mature anagen and all 20 early anagen hair bulbs, the melanocytes were strongly stained with HMB-45.In contrast, melanocytes in 11 mature anagen bulbs as well as in catagen or telogen phase were not stained.Our findings suggest that the expression of HMB-45 antigen in melanocytes of hair bulbs is strongly related to the cell cycle of hair,i.e.HMB-45 antigen only binds to the active or proliferating melanocytes in early and mature anagen hair follicles,but not to the inactive or dedifferentiated melanocytes in catagen of telogen hair follicles.

Key words: Melanocytes, Antibodies, monoclonal, Hair follicles