Antibodies against GM1 gangliosides associated with metastatic melanoma

The aim was to analyze humoral immune response against GM1 ganglioside expressed on the surface of melanocytic cells, and the possible correlation between the level of antibodies against GM1 IgG and IgM class and melanoma progression. The study included 128 adult patients with malignant melanoma, without paraneoplastic neurologic disorders, 48 adults with dysplastic nevi and 48 healthy volunteers. The presence of IgM and IgG antibodies against GM1 was demonstrated by Immunodot method. Automatic evaluation of strips marked with GM1 antigen was performed by EUROLineScan software. Lactate dehydrogenase (LDH) activity was evaluated by spectrophotometry. Serum concentration of gangliosides was determined using the method with resorcinol-HCl. IgG antibodies against GM1 gangliosides were identified in six patients with melanoma (4.68%) and in none of the subjects from other groups. AntiGM1 IgM class were observed in 20 (15.63%) melanoma patients, three (6.25%) dysplastic nevi patients and one healthy volunteer. No statistically significant difference was observed when serum profile of GM1 IgM antibodies in patients with localized melanoma was compared with that of other study subjects. The levels of IgM antibodies varied with clinical stage of tumor and histopathologic features. Moreover, a statistically significant positive correlation was found between IgM antibodies and LDH (r=0.87; p=0.01; IC=95%). In conclusion, antibodies against GM1 ganglioside are frequent in patients with melanoma. Dysplastic nevi and early melanoma cannot be differentiated using the antiGM1 antibody profile. The synthesis of these antibodies is characteristic for advanced stages of melanoma.