Opsonic phagocytosis of Streptococcus pneumoniae by alveolar macrophages is not impaired in human immunodeficiency virus infected Malawian adults

Streptococcus pneumoniae is a major cause of pneumonia, bacteremia, and men ingitis, especially among adults infected with the human immunodeficiency v irus (HIV). Alveolar macrophages (AMs) are critical components of cellular defense against bacterial infection and are both infected and affected by H IV. In this study, AMs obtained at bronchoscopy from 44 Malawian adults (24 HIV positive and 20 HIV negative) were exposed in vitro to opsonized S. pn eumoniae and coagulase-negative staphylococci. AMs from HIV-positive and -n egative volunteers showed no significant difference in binding to or intern alization of either S. pneumoniae or coagulase-negative staphylococci. In H IV-positive subjects, the presence of detectable HIV in lung fluid was not associated with AM impairment. AMs from HIV-infected adults did not exhibit impaired pneumococcal phagocytosis in the assay used. This suggests that a n alternative mechanism of susceptibility is operating in these individuals .