[Effect of cysteine ethylester hydrochloride (Cystanin) on host defense mechanism]

Cysteine ethylester (10 approximately 100 mg/kg, p.o.) augmented the production of hemolytic plaque-forming cells (HPFC) to sheep red blood cells and lipopolysaccharide in the spleen of mice. It showed no effect, however, on the HPFC production to trinitrophenylated polyvinylpyrrolidone; and it had no activity as a polyclonal B cell activator like lipopolysaccharide. Cysteine ethylester at a concentration of 3 microM or more potentiated the phagocytosis of yeast by the peritoneal polymorphonuclear leukocytes of rats. This activity was less potent than that of levamisole and D-penicillamine. It also potentiated the reduction of nitroblue tetrazolium (NBT) by blood leukocytes prepared from guinea pigs and a human being. This activity was more potent than that of levamisole and D-penicillamine. Furthermore, cysteine ethylester at doses showing an immunopotentiating activity protected irradiated mice from death by spontaneous infection. These findings suggest that this drug may have a capacity to potentiate the host defense mechanisms.