Role of apoptosis and melanocytorrhagy: a comparative study of melanocyte adhesion in stable and unstable vitiligo

Abstract

Apoptosis and melanocytorrhagy have been proposed as mechanisms of melanocyte disappearance although there are few controlled studies. We undertook this project to study melanocyte morphology and adhesion defects in patients with stable and unstable disease in controls. In this comparative study we included seven patients with stable disease and seven patients with unstable vitiligo. We cultured perilesional skin melanocytes from these patients with stable and unstable vitiligo and studied for morphological changes, adhesion to collagen type IV and caspase 3 expression. Melanocytes were also treated with okadaic acid and annexin V expression was then checked and compared between controls and patients with stable and unstable vitiligo. Perilesional skin melanocytes from patients with unstable vitiligo revealed some significant morphological changes. Melanocytes from unstable vitiligo showed significantly low adhesion to collagen type IV compared with control and stable vitiligo melanocytes. Our results showed that caspase 3 and annexin V staining was significantly greater in melanocytes cultured from unstable vitiligo compared with the control. In this study we demonstrated that melanocytes in the patients with unstable vitiligo were in their detachment phase, which ultimately leads to apoptosis of these cells, whereas melanocytes cultured from controls and from patients with stable vitiligo were morphologically normal without any adhesion defects. These morphological and adhesion findings support the theory of melanocytorrhagy as the primary defect underlying melanocyte loss in unstable vitiligo.