CTLA4 and vitiligo: If the immunosuppressive roles of CTLA4 and IL10 in Brown line chickens are confirmed, this would imply a common melanocyte-specific triggering of a T cell-driven immune response in both vitiligo-prone Smyth and -susceptible Brown line chickens with the former progressing to a cell-mediated autoimmune response and the later to an immunoregulatory response, perhaps resulting in the establishment of peripheral tolerance (anergy).