Myron Gordon Award paper: Microbes, T-cell diversity and pigmentation.

Melanocytes are static, minimally proliferative cells. This leaves them vulnerable in vitiligo. Yet upon malignant transformation, they form vicious tumors. This profound switch in physiology is accompanied by genetic change and is driven by environmental factors. If UV exposure in younger years supports malignant transformation and melanoma formation, it can likewise impart mutations on melanocytes that reduce their viability, to initiate vitiligo. A wide variety of microbes can influence these diametrically opposed outcomes before either disease takes hold. These microbes are vehicles of change that we are only beginning to study. Once a genetic modification occurs, there is a wide variety of immune cells ready to respond. Though it does not act alone, the T cell is among the most decisive responders in this process. The same biochemical process that offered the skin protection by producing melanin can become an Achilles heel for the cell when the T cells target melanosomal enzymes or, on occasion, neoantigens. T cells are precise, determined, and consequential when they strike. Here, we probe the relationship between the microbiome and its metabolites, epithelial integrity, and the activation of T cells that target benign and malignant melanocytes in vitiligo and melanoma.