CD4 and vitiligo: Since TRP-1 is expressed in normal melanocytes as well as B16.F10 melanoma, all animals receiving ACT of TRP-1-specific CD4+ T cells eventually experienced some autoimmune vitiligo, characterized by a patchy, irregular loss of pigmentation (Fig. 2B and E).11 However, mice receiving anti-NK1.1 therapy in addition to ACT of naive TRP-1 CD4+ T cells experienced more vitiligo by day 35 after treatment (Fig. 2B).