Electron-microscopic visualization of binding of antibodies from sera of Glioma patients on cultured glioma cells

Several human cell lines (normal and neoplastic glia, cerebral metastases from adenocarcinoma, fibroblasts) were incubated with sera from patients with well and poorly differentiated glioma and with sera from healthy donors and then stained with PAP complex to define and localize the antibody reaction with cell surface antigens by means of electron microscopy. The sera of glioma patients proved to contain antibodies which bound the tumor-associated antigenic determinants on the cell membranes of gliomas and of cerebral metastases from adenocarcinoma in tissue cultures. Further, absorption testing of the reactive sera on normal brain, well-differentiated astrocytoma and cultured glioblastoma cells, together with cross-reactivity experiments suggests that at least two antigens or groups of antigens are expressed on the glioma cell surface: one shared by well and poorly differentiated glioma cells and the other by poorly differentiated glioma cells and the cells of cerebral metastases from adenocarcinoma.