Reduction of skin-homing cytotoxic T cells (CD8+-CLA+) in patients with vitiligo

Background Vitiligo is a frequently acquired, hereditary disease, characterized by achromic macules due to the absence of melanocytes. In contrast with earlier studies, in which the main pathogenic role was attributed to anti-melanocyte antibodies, recent papers have emphasized a role for CD8+ cytotoxic T lymphocytes in melanocyte destruction. Fifteen percent of peripheral T cell express cutaneous lymphocyte-associated antigen (CLA), responsible for skin-homing T cell. Phototherapy is used to treat patients with generalized vitiligo and it has been shown to interfere with CLA+ T cells in other skin diseases. Objective To describe peripheral blood T cell subpopulations' frequency and ability to express the skin-homing molecule (CLA) in patients with non-segmental vitiligo, before and after photochemotherapy (PUVA). Patients and Methods Twenty-two patients with generalized and active spreading vitiligo were submitted to 30 PUVA-8MOP sessions. Lymphocyte immunophenotyping was performed by flow cytometry using anti-CD3, anti-CD8 and anti-CLA monoclonal antibodies. Fifteen healthy volunteers, sex- and age-matched, were included as a control group. Results CD8+-CLA+ T cells were significantly reduced in number in untreated vitiligo patients (P=0.008) when compared with control individuals, albeit with a more intense CLA expression (P=0.028). These findings were not altered after PUVA. No significant difference was noticed in CD4/CD8 ratios nor in CD4-CLA+ T cell numbers between vitiligo patients and controls, both before and after PUVA. Conclusions CD8-CLA+ T cells are reduced in peripheral blood of patients with non-segmental vitiligo. This finding may be related to the previously reported increase of CD8+ cells in both lesions and perilesional skin of these patients.