Enhancement of bronchoalveolar cell recovery and stimulation of alveolar macrophage chemiluminescence and resistance to influenza virus after treatment with RU 41821 aerosol.

Aerosol treatment with RU 41821, a glycoprotein extract from Klebsiella pneumoniae, was tested in mice for its effect on the kinetics of the induction of bronchoalveolar cells (i.e., alveolar macrophages, monocytes, lymphocytes, and polymorphonuclear leukocytes). RU 41821 led to an increase in the total number of bronchoalveolar cells. The largest increase was observed for polymorphonuclear leukocytes, and more moderate increases occurred in the numbers of alveolar macrophages, monocytes, and lymphocytes. The alveolar macrophages recruited in response to RU 41821 were activated, as indicated by luminol-dependent chemiluminescence in response to stimulation by opsonized zymosan. The effects of five RU 41821 aerosol treatments and those of a single treatment were further examined in vivo by aerosol infection of mice inoculated with a mouse-pathogenic influenza virus. The maximum protective effect was obtained after five once-a-day treatments and was correlated with the largest increase in the total number of bronchoalveolar cells.