RU-41740 (K. pneumoniae glycoprotein) enhances resistance to experimental candidiasis and stimulates phagocytic...

RU-41740, a purified glycoprotein extract from Klebsiella pneumoniae, (which is an efficient non-specific immune activator in a broad spectrum of in vitro and in vivo reactions) was administered either orally or parenterally in the mouse. It enhanced the resistance of mice to candidiasis, both in terms of survival rate and a decrease in viable yeast cell recovery in kidneys. The drug administered at 0.1 mg or 1 mg/kg augmented 4-fold the mean survival time (MST) of animals infected with 1 to 2 X 10(6) Candida albicans, both by the intraperitoneal and the intravenous route. The effect of the orally administered drug was less striking but nonetheless present. At 10 mg/kg, the MST of infected animals increased about 2-fold. In vitro, in the presence or absence of zymosan, the drug at 10 or 100 micrograms/ml was able to stimulate the phagocytic process of elicited mouse peritoneal cells (65% polymorphonuclear cells, 35% macrophages) and human peripheral blood cells (95% polymorphonuclear cells, 5% monocytes) in terms of activated oxygen species production. The involvement of polymorphonuclear cells in the mechanisms of natural resistance to C. albicans infection led us to discuss the role of these cells as targets for the drug.