Melanosomal proteins as melanoma-specific immune targets.

Pigmentation of our skin, hair and eyes is essential for photoprotection, embryological development, detoxification and protective/cosmetic coloration. A number of proteins important to the production of melanin within melanosomes have now been identified including enzymatic and structural proteins encoded at the murine albino, brown, pinkeyed-dilution, MART1, slaty and silver loci. Interestingly, many of those melanosomal proteins (including epitopes derived from tyrosinase, TRP1/gp75, silver/gp100 and MART1/melan-A) function in vivo as targets of humoral and cellular autoimmune responses directed specifically against normal or transformed melanocytes. These findings have provided new impetus to research on immune responses to melanoma and, perhaps more importantly, examining why they are insufficient to provide protection against tumour growth and what type of immune therapy can be designed to correct that. The melanosome must now be considered beyond its function in pigmentation, and assumes the role of a valuable source for specific immune targets for malignant melanoma.