Simultaneous demonstration of glia- and glioma-associated antigens in human astrocytomas.

Glial fibrillary acidic protein (GFAP) and glioma-associated antigens (GAA) defined by monoclonal antibodies (MAbs) were demonstrated simultaneously in human astrocytoma tissue. GFAP was stained by PAP-method, GAA were visualized by avidin-biotin-technique using alkaline phosphatase. In primary and secondary tumors as well as in tissue culture heterogeneity of GFAP- and GAA-expression is obvious. GFAP is mostly restricted to cell processes and less marked in the perinuclear space. Depending on the individual antibody, MAbs-positive material is located either in the tumor cell plasma (MUC 8-22) or on cell surface membranes (MUC 2-63). There is remarkable expression of GAA in cell clusters which fail to express GFAP. At higher magnification, 3 types of cellular reactivity are detectable: (a) cells which react only with anti-GFAP, (b) cells which react only with anti-GAA and (c) cells which express both, GFAP and GAA, especially those of protoplasmic astrocyte type. These cells also occur in subcutaneous tumor grafts, and may thus represent not only a reactive event, but be part of tumor cell populations.