Biosynthesized products of cultured neuroglial cells I. Selective release of proteins by cells from human astrocytomas

The proteins synthesized and released by human astrocytoma cells cultured with radiolabeled amino acids were analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate and by trichloracetic acid precipitation. A select group of extracellular proteins was released from the astrocytomas. The most abundant extracellular proteins were at least 250,000 daltons. Five other major proteins ( p 175, p 125, p 60, p 47, and p 40) were 175,000, 125,000, 60,000, 47,000, and 40,000 daltons, respectively. The complement of proteins retained by the cells was considerably more complex than those released. Clinical efforts to enhance the immunologic response directed against human astrocytomas must distinguish between extracellular and retained antigens. The pattern of proteins released by gliomas might be diagnostically useful if present in cerebrospinal fluid or serum.