Antisera reactive with the ganglioside GM2 were raised by immunizing C57BL/6 mice with the C57BL/6 melanoma JB-RH. Fusion with NS-1 was performed using splenic mononuclear cells from a mouse with high antibody titer. An immunoglobulin M monoclonal antibody (monoclonal antibody 5-3) was identified which was reactive with an antigen that was resistant to heat, trypsin, and Pronase. A panel of purified glycolipids was used to determine the specificity of monoclonal antibody 5-3. Reactivity was restricted to N-acetyl- and N-glycolyl-GM2. No reactivity was detected with asialo-GM2 or other gangliosides. Monoclonal antibody 5-3 was used to define the expression of GM2 on the cell surface of cultured human normal and malignant cells. Reactivity was seen with cell lines derived from 8 of 8 astrocytomas, 5 of 5 neuroblastomas, 7 of 9 sarcomas, 4 of 18 human melanomas, 2 of 4 murine melanomas, 4 of 37 epithelial cancers and with 0 of 6 skin fibroblast and 0 of 2 brain fibroblast lines. GM2, like GD2 and GD3, appears to be a differentiation antigen largely restricted to cells of neuroectodermal origin.

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This work was supported in part by grants from the National Cancer Institute (CA-36120, CA-08748, CA-33049) and from the Tortuga Foundation.

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