Auroantibodies to tyrosinase: Crossroad between vitiligo and melanoma

Tyrosinase is an enzyme which participates in the process of melanin production in melanocytes. Recently we defined tyrosinase as a novel autoantigen in vitiligo - an autoimmune disorder manifested by the presence of white patches on the skin resulting from destruction of melanocytes by the immune system. Antibodies against tyrosinase were detected in the sera of patients with melanoma associated with white patches on their skin. These white patches imply for better prognosis and the presence of anti-tyrosinase antibodies in these patients may be regarded as an additional parameter of disease state. In the present study two beneficial clinical applications of anti-tyrosinase antibodies were evaluated The first entailed anti-tyrosinase antibodies as a marker for monitoring and follow-up of patients with melanoma treated by immunotherapy. Seven patients with metastatic melanoma were treated by vaccination with anti-idiotypic antibodies mimicking the high molecular weight melanoma associated antigen. The titer of anti-tyrosinase antibodies increased following the vaccination and then decreased most probably due to absorption to melanoma cells and melanocytes. The development of anti-tyrosinase antibodies in response to vaccination by another antigen may be explained by induction of non-specific polyclonal B-lymphocyte activation. The second employed therapeutic application of anti-tyrosinase antibodies. We have shown that C57BL/6J mice immunized with tyrosinase generated a high titer of anti-tyrosinase antibodies and following the inoculation of melanoma cells developed lower number of lung metastaces compared to an unvaccinated control group.