We developed a model of cancer cachexia by transplanting VX2 tumors into rabbits and investigated the effects of plasmapheresis in this model. AIS activity was identified in supernatants obtained from VX2 tumor by phenyl Sepharose chromatography. Fractions eluted with 0.5 M NaCl showed the ability to damage the red blood cell membrane and suppress immunity. Rabbits exhibited marked weight loss, anemia and immunodeficiency 40 days after transplantation of VX2 tumors. Plasmapheresis inhibited plasma-induced damage of the red blood cell membrane and suppression of immunity. Twice-weekly plasmapheresis resulted in gradual normalization of cellular immunity. Weight loss and survival were also improved. No side effects were observed.