| Objective Vitiligo is an acquired disorder of depigmentation characterised by the loss of pigment from epidermis. Histologically, melanocytes (MC) are not visible in the depigmentation areas of vitiligo. To study the recovery of MC in the depigmented areas should be significant in understanding the pathogenesis and developing therapeutic methods of vitiligo. In the present study, we detected the expressions of HMB45 antigen, tyrosinase(TYR), tyrosinase related protein(TRP)-1 and tyrosinase related protein(TRP)-2 , to investigate the cell structure and function and the cell distribution in epidermis basal layer of the MCs, and the possible cause of the abnormal morphology of the MC, in the repigmentation areas of vitiligo.Methods Fifteen specimens from the repigmented areas of vitiligo were collected, and 15 specimens from the depigmented macules of vitiligo and 10 from normal skin of healthy persons were taken as controls. Expressions and distributions of HMB45 antigen,TYR,TRP-1 and TRP-2 in all of the specimens were investigated with immunohistochemical ABC method. When cytoplasm revealed yellow staining with HMB45 antigen,TYR and TRP-2, there was a positive result. When cytoplasm and/or nucleus membrane revealed yellow staining with TRP-1, there was a positive result. The average number of MC expressing HMB45 antigen in every 100 basal layer cells was counted single blindly, and was compared among the 3 groups. Expressions of the 4 MC specific markers were analyzed quantitively with image analysis system(model HPIAS-1000).Results In the depigmented macules of vitiligo, the average number of MC in every 100 basal layer cells was 0. No expressions of all the 4 MC specific markers were observed. Compared with normal skin, the average numbers of MC in the repigmentation of vitiligo were fewer, but without significant statistics difference between them(P>0.05). Expressions of those 4 MC specific markers were all positive. The expression of HMB45 antigen in repigmented area of vitiligo was equal to that in normal skin(P>0.05)and the expression intensity of HMB45 antigen among the 3 groups was as the follows: repigmentation group = normal skin group > depigmentatiaon group. The expression of TYR in repigmented area of vitiligo was stronger than that in normal skin(P<0.05). The expression intensity of TYR among the 3 groups was as the follows: repigmentation group > normal skin group > depigmentatiaon group. The expression of TRP-1 in repigmented area of vitiligo was significantly stronger than that in normal cutaneous constitution(P<0.01). The expression intensity of TRP-1 among the 3 groups was as the follows: repigmentation group > normal skin group > depigmentatiaon group. The expression of TRP-2 in repigmented area of vitiligo was equal to that in normal skin(P>0.05), and the expression intensity of TRP-2 among the 3 groups was as the follows: repigmentation group = normal skin group > depigmentatiaon group. In 13 samples, MCs distributed around follicles and in other 2 samples MC distributed evenly around follicle and in epidermis basal layer. Compared with the normal MC in the epidermis of healthy persons, MC in the repigmentation areas of vitiligo were bigger and the dendrites were fewer, shorter and thicker.Conclusions 1)MC with integrated cell structure and ability to synthesis melanin are loss in the depigmented epidermis of vitiligo. 2)In the present study, 4 MC specific markers were used to study the repigmentation areas of vitiligo immunohistochemically. To our knowledge, this has not been reported in the literatures. 3)There are MCs in the repigmentation areas of vitiligo, and most of them have integrated MC structure and ability of synthesizing melanin. 4)The results of the present study support the point of view that MCs in the repigmentation areas come from the tissue of hair follicles, indicating that to study the proliferation, differentiation and migration of the MCs in the tissue of hair follicles might be significant in treatment of vitiligo. On the other hand, the p...
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