Abstract: Objective To investigate the status of apoptosis of keratinocytes and the expression of several apoptosis-related proteins in keratinocytes in the depigmented skin of patients with progressive vitiligo. Methods Depigmented skin samples of 15 patients with progressive vitiligo and normal skin specimens of 15 healthy subjects undergoing plastic swgery were obtained. Apoptosis of keratinocytes was determined by the terminal deoxynucleotidyl transferase end-labeling(TLTNEL) assay. The expression of Bax, Bcl-2 and Caspase 3 was evaluated by immunohistochemistry. Results The apoptotic keratinocytes, distributed mainly in the middle and lower epidermis, were identified in situ by the TLTNEL assay on sections from all depigmented skin samples, whereas only scattered apoptotic keratinocytes were found in one normal skin section. A significant increase of apoptotic keratinocytes in vitiligo skin was found compared with normal controls(P<0.01).The positivity rate of Bax protein in keratinocytes in depigmented skin was significant higher than that in normal controls(7/15 vs 1/15, P<0.01),whereas no expression of Bcl-2 and Caspase 3 was detected in both groups. Conclusion These results indicate that there is enhanced expression of Bax in keratinocytes and an abnormal increase of apoptotic keratinocytes in depigmented skin of patients with progressive vitiligo.

Key words: Vitiligo, Keratinocytes, Apoptosis, Bax