Antigen variation in a human glioblastoma: from the primary tumor to the second recurrence, permanent cell line and xenotransplantation tumors.

Antigen expression in a human glioblastoma was investigated by immunochemical methods in the primary tumor, the first and second recurrence, a permanent cell line derived from the first recurrence and in its xenotransplantation tumors. In the primary tumor, GFAP, vimentin, S100, Leu-7 and glioma-associated antigens (GAA) as defined by the monoclonal antibodies (mAbs) MUC 2-39, MUC 8-22 and MUC 2-63 were markedly expressed. In the recurrences, gradual loss of GFAP and Leu-7 could be observed, whereas S100, vimentin and GAA gave similar results to those in the primary tumor. In contrast, fibronectin and collagen IV, which were restricted to the vessel walls in the primary tumor, were represented in sarcomatous areas of the recurrences. In some of these areas, co-expression of glial cell markers was observed. In short-term cell cultures, expression of glia- and glioma-associated antigens as well as fibronectin and collagen IV was comparable to that of the recurrent tumor tissue. In long-term passages, immunoreactivity of GFAP, Leu-7 and S100 decreased, whereas GAA, vimentin and fibronectin increased. Collagen IV positive cells were not visible beyond passage 15. Transplantation tumors were only partly positive for glial cell markers, but revealed strong immunoreactivity for GAA, fibronectin and collagen IV. With these observations we confirm that the phenotypic variability of glioma cells makes it difficult to identify the origin of cells in human glioblastomas from their antigenicity.