EXPRESSION OF ANTIGENS DEFINED BY THE MONOCLONAL-ANTIBODY AT5 IN CULTURED NEURAL CELLS AND IN HUMAN BRAIN-TUMORS OF GLIAL ORIGIN

Monoclonal antibody At5 was primarily developed against chordin, a not ochord-specific antigen of sturgeon fishes. In higher vertebrates the antibody reacted mainly with antigens of neural tissue. In this study the expression of At5 reactive antigens was examined in cultures of di ssociated human and rat neural cells. The data presented here show tha t the antigens recognized by the monoclonal antibody At5 can be expres sed by any of main cell types composing the neural tissue: the neurons , astrocytes and oligodendrocytes. In situ immunohistochemical studies showed that the majority of human glial tumors investigated were labe led by the monoclonal antibody At5, contrary to meningiomas which did not exhibit the At5 immunoreactivity. In oligodendrogliomas and mixed oligoastrocytomas strong At5 immunoreactivity was observed in oligoden droglial cells whereas in an anaplastic astrocytoma At5 immunoreactivi ty was characteristic for spindle-like astrocytes with long processes but not for large protoplasmic astrocytes. We conclude here that the s pecificity of the monoclonal antibody At5 is similar to that of previo usly generated monoclonal antibody HNK-1 but is more restricted in som e cases. Two At5 reactive antigens of very high molecular weight simil ar to those of human embryonic brain have been identified in an oligod endroglioma.