Peritoneal mesothelial cells as a significant source of ascitic immunostimulatory protein 90K

The tumor associated antigen 90K is known to possess cytokine-like modulato ry properties an the cellular immune system, whereby accessory cells are th e primary target of this molecule. In 67 ovarian cancer patients presenting with significant amounts of ascites, immunostimulatory protein 90K was det ected in all ascitic fluid samples examined. Furthermore, 90K levels correl ated to ascitic s-IL-2R content. To elucidate the source of protein 90K in ascitic fluid its in vitro release was investigated in primary cultured nor mal human peritoneal mesothelial cells (HPMC). Peritoneal mesothelium was f ound to produce five-fold more 90K than ovarian cancer cells. Release of pr otein 90K was significantly increased by treatment with IFN-gamma in both m esothelial and ovarian cancer cells. In contrast neither IL-1 beta nor TNF- alpha treatment consistently influenced the secretion of 90K in either cell type.