Abstract: Objective To identify the melanocyte surface antigens associated with vitiligo by a proteomic approach. Methods Sera were screened for the presence of a high titer of antibodies against melanocytes from 256 patients with vitiligo by cellular enzyme-linked immunosorbent assay(cellular ELISA)and Western blotting. The membrane proteins of melanocytes were extracted and separated by two-dimensional gel electrophoresis(2-DE).Separated membrane proteins were transferred to polyvinylidene difluoride(PVDF)membrane and immunoblotted with either pooled sera of 10 patients with vitiligo or those of healthy controls. The different spots were analyzed by image analysis software, followed by identification using the bioinformatics tool of ExPASy(Expert Protein Analysis System)proteomics server. Results About 500 distinct protein spots were identified by 2-DE, of which 3 spots were unique to the sera of patients with vitiligo. One of them was identified as melanin-concentrating hormone receptor 1(MCHR-1), a known autoantigen of vitiligo. The other two proteins could not be identified using the bioinformatics tool and might need to be identified by mass spectrometry. The apparent molecular weight and isoelectric point of one protein were determined to be 75 000 and 6.5, whereas those of another one were 60 000 and 5.5, respectively. Conclusion Three melanocyte surface antigens are identified as candidate autoantigens in vitilieo by nroteomic analysis. One of them is MCHR-1, and the other two remain to be identified.

Key words: Vitiligo, Proteomics, Melanocytes, Membrane proteins, Autoantigens