The aim of this study was to determine the presence and the intensity of humoral immunity to melanoma-associated antigens: tyrosinase and melanin, in patients with melanoma, in persons with vitiligo and in control healthy people.
The study involved 63 patients with melanoma and 19 persons with vitiligo. Control group consisted up to 41 healthy volunteers. Mushroom tyrosinase and synthetic melanin were used as the antigens.
ELISA test showed significantly (p<0.0000004 and p<0.04) lower levels of IgM anti-tyrosinase autoantibodies, in melanoma and vitiligo patients respectively, compared to controls.
Although there was no significant difference between the levels of IgA anti-melanin autoantibodies in melanoma or vitiligo patients in comparison with controls, the enhanced concentrations of anti-melanin IgA autoantibodies were preferentially found in melanoma patients with metastatic disease. Significantly high percentage in the Fc alphaRI (CD89) positive cells was determined in melanoma patients (p<0.002 and p<0.008) in comparison to that found in healthy people or in patients with vitiligo, in the already mentioned order, pointing that IgA dependent cellular cytotoxicity is not important for the immune action against melanoma, even more that it is included in some immune suppression.
Levels of IgG autoantibodies to mentioned antigens in melanoma patients although low were not significantly lower from controls. These findings analyzed together with the statistically significant low percentage of FcgammaRIII, (CD16) positive immunocompetent cells (p<0.0007 and p<0.003), which was found in patients with melanoma compared with healthy or vitiligo people respectively, and statistically significant low percentage of (CD16+CD56+) natural killer (NK) cells (p<0.005) found in melanoma patients in comparison to healthy controls pointed to the low probability for anti-melanoma IgG mediated, antibody mediated cellular cytotoxicity, (ADCC) and NK cytotoxicity. Moreover the ratio of the percentages of granulocytes and percentage of lymphocytes was statistically higher in patients with melanoma in relation to healthy people as well as to people with vitiligo (p<0.0007 and p<0.05 respectively).
Autoantibodies to tyrosinase and to melanin which are found even in healthy people, point that consummation of edible mushrooms that carry the antigen tyrosinase and melanin, could influence the humoral anti-melanoma immune response.
Levels of different immunoglobulin classes of anti-melanin and anti-tyrosinase antibodies varied depending on the presence and the stage of studied diseases. Besides, the statistically enhanced ratio of the percentages of granulocytes and percentage of lymphocytes, together with statistically decreased percentage of NK cells is found in analyzed melanoma patients.
Keywords: Melanin, Tyrosinase, Melanoma, Vitiligo, Anti-tyrosinase antibodies, Anti-melanin antibodies, CD16+ CD56+, CD89+