Effect of cysteine ethylester hydrochloride (Cystanin) on host defense mechanisms (V): Potentiation of nitroblue tetrazolium reduction and chemiluminescence in macrophages or leukocytes of mice or rats

L-Cysteine ethylester hydrochloride (Cystanin, ethylcysteine) at doses of 3-30 mg/kg, p.o., potentiated the reduction of nitroblue tetrazolium (NBT) by mouse peritoneal macrophages ex vivo. In in vitro experiments, this drug (30 microM) augmented NBT reduction of mouse peritoneal macrophages induced by opsonized zymosan (OZ). At the same concentration, this drug accelerated the enhancement of the OZ-induced NBT reduction by the addition of concanavalin A, N-formyl-L-methionyl-L-leucyl-L-phenylalanine or phorbol myristate acetate. This enhancing effect of ethylcysteine was completely diminished by the addition of SOD, sodium azide and catalase. In ex vivo experiments, the OZ-induced chemiluminescence of rat peritoneal macrophages and white blood cells was enhanced by the administration of ethylcysteine at doses of 3-10 mg/kg (i.p.) and 3-30 mg/kg (p.o.). In addition, this drug significantly enhanced the lumisphere-induced chemiluminescence of rat peritoneal leukocytes at 30 mg/kg (i.p.), but not the OZ-induced chemiluminescence. In in vitro experiments, this drug (30 microM) did not enhance the OZ-induced chemiluminescence response of rat peritoneal macrophages. These results suggest that ethylcysteine may enhance the intracellular generation of antimicrobial oxidants in macrophages and leukocytes.