Expression of immune checkpoints in active nonsegmental vitiligo: a pilot study

Background: Vitiligo is a depigmentary skin disfigurement resulting from destruction of melanocytes caused by a possible malfunctioning immunity. This destruction could be linked to an aberrant T-cell–mediated immune response. Cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4) and programmed death-1 (PD-1) are immune checkpoints capable of downregulating T-cell immune functions. Objectives: To evaluate the pattern of expression of PD-1 and CTLA-4 in active vitiligo skin. Methods: Thirty nonsegmental vitiligo (NSV) patients had been included in this pilot study. Marginal, lesional, and nonlesional skin biopsies were obtained. PD-1 and CTLA-4 immunohistochemistry expression in the mononuclear inflammatory infiltrates were evaluated using digital images. Results: The marginal and lesional inflammatory infiltrates were significantly abundant when compared to nonlesional ones. The marginal infiltrates were significantly abundant when compared to the lesional ones. PD-1 and CTLA-4 were significantly expressed in the marginal and lesional infiltrates when compared to nonlesional skin. Moreover, the marginal expression of PD-1 was significantly higher than the lesional expression. However, no similar significant difference in CTLA-4 expression was found between the marginal and lesional infiltrates. Significant positive correlations were found between the expressions of PD-1 and CTLA-4 in marginal and lesional infiltrates. Conclusion: Programmed death-1 and CTLA-4 are expressed within the inflammatory infiltrate of active NSV. Further studies are required to confirm their significance in the development or limitation of the disease.