Immunoglobulin G Fcγ receptor expression on polymorphonuclear cells in bronchoalveolar lavage fluid of HIV-infected and HIV-seronegative patients with bacterial pneumonia

This studywas designed to test the hypothesis that impaired neutrophil function might contribute to the development of bacterial pneumonia in patients with HIVinfection. Numbers of inflammatorycells and immunoglobulin G Fcgamma receptor (IgG FcgammaR) I, II, III levels were investigated in bronchoalveolar lavage (BAL) fluid of HIV-seronegative and HIV-infected patients with bacterial pneumonia. The 99 patients were classified into three groups: I: HIV-seronegative and pneumonia (n=40); II: HIV-infected and pneumonia (n=19); III: HIV-seronegative with other pulmonary diseases than pneumonia (n=40). The results of groups I and II, II and III, and I and III were compared. The percentage of alveolar macrophages was significantlylower (group II vs. III: p=0.005, group I vs. III: p=0.001), that of neutrophils increased significantly in patients with pneumonia (group II vs. III: p=0.02, group I vs. III: p=0.01). Lymphocytes differed only between groups I and III (p=0.04). Although onlythe expression of FcgammaRI was significantlyhigher in HIV-seronegative pneumonia patients compared to those without pneumonia (p=0.01), the mean expression of all three receptors was lower in the HIV-infected group, with that of FcgammaRI approaching statistical significance. This report provides first evidence that altered FcgammaR expression on BAL neutrophils might contribute to the increased susceptibilityof HIV-infected patients to bacterial pneumonia.