Abstract: Objective: To determine the killing mechanism of CD8⁺T cells to melanocytes in the patients with vitiligo.  Methods: CD8⁺T cells  were obtained from peripheral blood in 8 patients with vitiligo and 8 healthy controls. The primary melanocyte, immortalized normal melanocyte cell line PIG1 and immortalized vitiligo melanocyte cell line PIG3V were co-cultivated with selected CD8⁺T cells respectively. The number of the death of melanocytes killed by CD8⁺T cells was assessed by Flow cytometry. The expression levels of IFN-γ, TNF-α, granzyme B and perforin were measured by ELISA. Results: The number of died primary melanocytes and PIG3V killed by CD8⁺T cells, the expression level of IFN-γ, granzyme B and perforin in the patients with vitiligo was higher than those in controls. There was no significant difference in the number of died PIG1 and the expression level of TNF-α between the patients and healthy controls. There was an obviously positive correlation between the level of IFN-γ secreted by CD8⁺ T cells and the number of died melanocytes killed by CD8⁺T cells. Conclusion: The killing of melanocytes by CD8⁺T cells plays an important role in the development of vitiligo, which probably depends on the increased expression of IFN-γ, granzyme B and perforin.

Key words: vitiligo, CD8⁺T cells, IFN-γ, granzyme B, perforin