Evaluation of the Role of Apoptosis in Vitiligo: Immunohistochemical Expression of P53, Bcl-2 and MART-1 Antigens

Abstract

It is clear that melanocytes are absent from the vitiliginous skin. However, the mechanism of melanocyte disappearance has never been clearly understood. It is not clear whether melanocyte loss in vitiligo results from apoptosis or other causes of cell death. A very few data were published about the role of apoptosis in vitiligo. To investigate the role of apoptosis in vitiligo, ten biopsies from patients and ten normal control biopsies were taken from the skin of the thigh by the scalped biopsy technique. Each biopsy included adjacent areas of the lesional, peri-lesional and non-lesional skin. All subjects were males selected at Al-Housein University Hospital and ranged between 25 to 43 years in age. The expression of MART-1 protein as a melanocyte marker, Bcl-2 as an antiapoptotic molecule and P53 as a proapoptotic molecule were evaluated by the immunoperoxidase technique and computerized image analysis. The study revealed complete absence of MART-1 positive melanocytes in the lesional skin, gradual appearance in the peri-lesional areas and showed no significant difference between the non-lesional areas and the normal skin (P=0.43). The melanocytic Bcl-2 expression was higher in normal skin than the non-lesional area, lower in the peri-lesional areas and lowest in the lesional areas (p<0.05). Conversely, more expression of melanocytic P53 was seen in the lesional than the peri-lesional areas, lower in the nonlesional skin and lowest in the normal skin (p<0.05). Accordingly, the study revealed more susceptibility to apoptosis in the vitiliginous skin than in normal skin. We hope that these data can help in understanding the pathogenesis and the progression of this disease as well as providing better lines of its treatment.