Pulmonary defense mechanisms and the interaction between viruses and bacteria in acute respiratory infections.

Pulmonary virus infections are known to predispose to bacterial infections in the lung. The mechanism by which the virus renders the pulmonary system more susceptible to bacterial infection is reviewed. The bacterial multiplication associated with virus infections is related to defects in in situ bactericidal (phagocytic) mechanisms of the lung. This phagocytic dysfunction is localized to the intracellular killing mechanisms of the alveolar macrophage phagocytic process.