Recognizes a protein of 42-46kD, identified as MAGE-1. This monoclonal antibody does not cross-react with MAGE- 2, -3, -4, -6 -9, -10, -or -12 protein. Human malignant neoplasms carry rejection antigens that are recognized by the patients' autologous, tumor directed and specific, cytolytic, CD8+ T lymphocyte clones (CTL). The MAGE family of genes codes an important group of antigens. It was identified that melanomas and primary glial brain tumors express common melanoma associated antigens (MAAs). Because MAGE-1 is expressed on a significant proportion of human neoplasms of various histological types (melanoma, brain tumors of glial origin, neurobla stoma, non-small cell lung cancer, breast, gastric, colorectal, ovarian, renal cell carcinomas) and not on normal tissues, the encoded antigen may serve as a marker of early detection and target for cancer immunotherapy.