Morphological and biochemical alterations of macrophages produced by a glycan, PSK

A glycan extracted from Coriolus versicolor (PSK, Krestin) which has antitumor and immunomodulator properties produced marked morphological and biochemical changes when added to cultures of mouse peritoneal macrophages. The cells were more spread and elongated than in control cultures, and these changes were accompanied by alterations in the rate of protein and DNA synthesis. In PSK-treated murine peritoneal macrophages the rate of protein synthesis increased above the level seen in control cultures after two days and reached a level twenty-fold higher than control on day four; this elevated rate of protein synthesis was maintained throughout the seven-day observation period. DNA synthesis was induced after four days in the presence of PSK, and reached a level ten-fold higher than control baseline on day five. This induction of DNA synthesis, however, could not be attributed to a mitogenic activity on lymphocytes. The alterations caused by PSK in macrophage metabolism may be related to the immunomodulating and antitumor activities of PSK in vivo.