Sequential immunohistochemical study of depigmenting and repigmenting minigrafts in vitiligo.

The initial steps of melanocytic dysfunction in vitiligo are hitherto not well understood. The aim of the present study was to examine the sequence of early events that occur in melanocytes after autologous minigrafting in patients with vitiligo, depending on their clinical response. Six patients with non-segmental widespread vitiligo were included in the study. Specimens of vitiliginous lesions were used as preoperative controls and sequential punch biopsies were taken from the grafted areas on days 14, 17, 21 and 28 after minigrafting. Immunohistochemical stains using the MoAbs HMB-45, CD4, CD8, ICAM-1, and LFA-1 were performed in all biopsies and the labelled cells were counted by a digital image analyser. Results obtained show that in vitiligo patients not responding to minigrafting, significant numbers of cytotoxic T-lymphocytes and LFA-1 positive infiltrating cells occur in early phases (p < 0.05), suggesting that a cell-mediated immune response takes place towards the grafted melanocytes. Possibly this cell-mediated mechanism causing unresponsiveness to minigrafts may also play a role in the pathogenesis of vitiligo.