Abstract
Non-specific activation of host defences may have a significant impact on the outcome of infections in the immunocompromized patient. RU 41740, a glycoprotein extract fromKlebsiella pneumoniae, effective in increasing resistance to experimental infections in animals, has been examined in vitro for its effect on human blood monocyte locomotion, phagocytosis, killing ofCandida albicans, and release of superoxide anion. RU 41740 had no chemo-attractant activity nor any effect on monocyte chemotactic and phagocytic function. Candidacidal capacity and superoxide anion production by monocytes were significantly enhanced after preincubation with RU 41740 >1.0 µg/ml. The effect was dose- and time-dependent and was not influenced by the presence of lymphocytes or their culture supernatants. This suggests a direct interaction with monocytes as the mechanism of action of the extract.