IMMUNOREACTIVITY OF HUMAN MAB BT32 A6 WITH NEUROEPITHELIAL TUMORS/

The present study was undertaken to determine the pattern of immunorea ctivity of BT32/A6, a human IgM monoclonal antibody (MAb), with the fo llowing histological panels: 1) 30 human and non-human cell lines, 2) 32 normal human tissues, and 3) 28 tumors of central neuroepithelial o rigin (16 astrocytic; 11 non-astrocytic). Antibody BT32/A6 recognizes a surface and cytoplasmic antigen present on a variety of human tumor cell lines including gliomas, melanomas, neuroblastomas, and a few sar comas. The antigen is present (at least focally) on 15/16 astrocytic t umor tissue sections (94%), and in some cases, on close to 100% of cel ls. All malignant cell types, including small anaplastic cells, giant cells, gemistocytic cells, and cells forming pseudopalisades were labe led by MAb BT32/A6. Non-astrocytic neuroepithelial tumors did not stai n appreciably with MAb BT32/A6. There was weak immunoreactivity in a s mall subset of normal human tissues of epithelial and lymphoid origin, with the exception of adrenal cortex, which exhibited weak to moderat e staining. All normal tissues of neuroectodermal and mesenchymal orig in were unreactive. In conclusion, MAb BT32/A6 appears to be unique in that it recognizes a highly-expressed astrocytic tumor-associated ant igen that is present on both low and high grade tumors. This makes it a strong candidate for further studies aimed at establishing its usefu lness in the treatment of human astrocytic tumors.