Increase in the number and the phagocytic function of guinea pig pulmonary and peritoneal macrophages following oral administration of RU 41740, a glycoprotein extract from Klebsiella pneumoniae.

RU 41740 (Biostim) which is a purified glycoprotein extract from Klebsiella pneumoniae, is an orally active non-specific immunostimulant. In guinea pigs, 8 days after a 7 days oral administration of RU 41740 (10 or 100 mg/kg/day), an increase in the cell population of the pulmonary and peritoneal cavities was observed, especially in that of the macrophages. RU 41740 also enhanced the phagocytic activity of both the alveolar and peritoneal macrophages, when their chemotactic activity was not significantly modified. This increase in the number of pulmonary macrophages and the stimulation of their phagocytic function might explain the protective effect afforded by the oral administration of Biostim against respiratory infections in patients with chronic bronchitis.