Effect of human urinary colony-stimulating factor on experimental Legionella pneumophila infection in guinea pigs

The effect of human urinary colony-stimulating factor (CSF-HU) on in-vitro phagocytosis of Legionella pneumophila, superoxide anion production and intracellular killing of Legion, pneumophila by guinea pig alveolar macrophages was studied. Alveolar macrophages when incubated with CSF-HU demonstrated enhanced phagocytic activity and superoxide production. The bactericidal activity of treated cells was enhanced when they were afterwards incubated with a low concentration of bacteria, but these cells failed to inhibit bacterial multiplication when they were incubated with bacteria in a 1:10 ratio. In vivo, an increase in the total peripheral leucocyte count in guinea pigs after intraperitoneal injection of CSF-HU occurred and this was accompanied by an increase in granulocyte and monocyte counts. A comparison of treatment of experimental Legion, pneumophila pneumonia with CSF-HU alone, ceftazidime alone and a combination revealed lower mortality rates in the group receiving combination therapy. These data suggest a possible function for CSF-HU of enhancing antibiotic therapy in Legionnaires' disease.