[Augmentation of the cytostatic activity of granulocytes by biological response modifiers (BRM)]

The effects of various biological response modifiers (BRM) such as Nocardia rubra cell wall skeleton (N-CWS), OK-432, muramyl dipeptide (MDP), Staphylococcal protein A, interferon, lymphokine on the cytostatic activity of granulocytes against cultured tumor cells were examined. The cytostatic activity of untreated granulocytes from 10 normal healthy volunteers ranged from 14% to 30%. Lymphokine obtained from the supernatant of lymphocytes cultured with Con A-Sepharose directly suppressed the DNA synthesis of K 562 cells in high concentration, however, other BRM showed no direct cytostatic activity. The cytostatic activity of granulocytes was augmented by low concentrations (2.5 micrograms/ml) of N-CWS, OK-432 and protein A as well as by high concentration (25 micrograms/ml) of MDP. However, the cytostatic activity was not influenced by alpha-interferon. The meanings and mechanisms of the elevation in cytostatic activity of granulocytes by BRM were discussed with regards to the clinical immunotherapy.