Immunosuppressor control as a modality of cancer treatment: effect of plasma adsorption with Staphylococcus aureus protein A.

In tumor-bearing hosts both cellular and humoral tumor-growth-enhancing factors are present. They cause immunosuppression and facilitate the growth of tumors. Very early during tumor growth these factors are either elicited by the tumor cells or induced by the host immunocytes. Among these immunosuppressive agents, circulating immune complexes appear to play a predominant role. They also activate suppressor cell activity. Plasma adsorption of CIC and IgG by protein A of Staphylococcus aureus has been reported to cause tumor regression. Plasma adsorption with protein A-collodion charcoal, protein A-silica, or protein A-Sepharose also induced tumorilytic reactions. Even direct infusion of protein A induced tumor regressions in rat mammary tumors. Recent studies showing tumor regressions following S. aureus Wood 46 plasma adsorption or infusion of normal plasma adsorbed over S. aureus indicate that specific blocking factor removal by plasma adsorption may not be the mechanism for causing tumor destruction. Results indicate that S. aureus plasma adsorption leaches a number of staphylococcal agents. Thus, it appears that staphylococcal agents, protein A, enterotoxin, and other factors are responsible for the induction of reactions leading to tumor destruction. A unified mechanism explaining the results obtained with plasma adsorption using protein A of S. aureus, or S. aureus Wood, or direct protein A infusion, was presented.