Isolation and characterization of anti-neoplastic sturgeon factors

Sephadex G-200 column chromatography was utilized to isolate three anti-neoplastic compounds (A, B and C) from sturgeon sera which were cytotoxic for human tumor cells but would not kill normal cells in vitro. Furthermore, it was found that most of the sturgeons studied produced one or more of these same compounds. Immunoadsorbent techniques were utilized to further purify and isolate the three factors in larger quantities. When these immunoadsorbent purified factors were studied by SDS-polyacrylamide gel electrophoresis, factors A and C consisted of only 2 protein bands with molecular weights slightly greater than 68,000 and factor B consisted of 8 - 10 protein bands with molecular weights ranging from 30,000 to approximately 70,000. Factor A was not destroyed by heating at 56 degrees C for 30 min and appears to kill tumor cells by binding to the target cells. Factor B also was not destroyed by heating at 56 degrees C for 30 min. However, this factor differs from factor A in that it did not kill by binding to the tumor cell. Instead, it appears that a soluble factor is responsible for the cytotoxic effects observed with factor B. Factor C is destroyed by heating at 56 degrees C for 30 min and this factor kills the tumor cells by binding to the target cells. These factors were also examined for their ability to enhance macrophage mediated cytotoxicity. Sturgeon factors A and B enhance macrophage mediated cytotoxicity whereas factor C has no effect on the ability of normal human macrophages to kill human tumor cells.