Immunoreactivity of human MAb BT32/A6 with neuroepithelial tumors

The present study was undertaken to determine thepattern of immunoreactivity of BT32/A6, a human IgMmonoclonal antibody (MAb), with the following histological panels:1) 30 human and non-human cell lines, 2)32 normal human tissues, and 3) 28 tumorsof central neuroepithelial origin (16 astrocytic; 11 non-astro-cytic).Antibody BT32/A6 recognizes a surface and cytoplasmic antigenpresent on a variety of human tumor celllines including gliomas, melanomas, neuroblastomas, and a fewsarcomas. The antigen is present (at least focally)on 15/16 astrocytic tumor tissue sections (94%), andin some cases, on close to 100% ofcells. All malignant cell types, including small anaplasticcells, giant cells, gemistocytic cells, and cells formingpseudopalisades were labeled by MAb BT32/A6. Non-astrocytic neuroepithelialtumors did not stain appreciably with MAb BT32/A6.There was weak immunoreactivity in a small subsetof normal human tissues of epithelial and lymphoidorigin, with the exception of adrenal cortex, whichexhibited weak to moderate staining. All normal tissuesof neuroectodermal and mesenchymal origin were unreactive. Inconclusion, MAb BT32/A6 appears to be unique inthat it recognizes a highly-expressed astrocytic tumor-associated antigenthat is present on both low and highgrade tumors. This makes it a strong candidatefor further studies aimed at establishing its usefulnessin the treatment of human astrocytic tumors.