REDUCED EXPRESSION OF MACROPHAGE-ASSOCIATED ANTIGENS ON ALVEOLAR MONONUCLEAR PHAGOCYTES FROM ACQUIRED-IMMUNODEFICIENCY-SYNDROME

In this study we evaluated the phenotype of alveolar mononuclear phago cytes recovered from the bronchoalveolar lavage fluid of 24 patients w ith human immunodeficiency virus infection (AIDS-related complex 8 pat ients, AIDS 16 patients) and 8 healthy individuals by using a panel of monoclonal antibodies known to react with tissue macrophages, in comb ination with a flow cytometer. The results showed that 90% of patients with AIDS present a marked reduction in the expression of several ant igenic determinants (in descreasing order: CD68, CD36, CR1, CD11c, HLA -DR). The levels of antigen expression by flow cytometry seem to decli ne with disease progression, showing the most dramatic perturbations i n patients with full-blown AIDS associated with pulmonary infections ( especially Pneumocystis carinii pneumonia) and lower peripheral CD4 ly mphocyte counts. In contrast, patients with AIDS-related complex or AI DS without histological or cultural evidence of pulmonary involvement showed, respectively, only minimal or medium antigenic decreases. Howe ver, only a minor proportion (16%, 20%, 20%, 25%, and 25% respectively ) of human immunodeficiency virus infected patients (mostly with AIDS) had a significant reduction of the levels of CD4, CD14, CD45R, CD11b, and CD16 antigens in the alveolar macrophages. Since macrophages play a central role in the pathogenesis of AIDS, it may be postulated that the loss of various phenotypic markers on alveolar mononuclear phagoc ytes (some of them known for their important immunoregulatory actions) could have an important part in the pathogenesis of human immunodefic iency virus induced immunosuppression, and thereby condition the abnor mal susceptibility to pulmonary diseases typical of human immunodefici ency virus-infected patients.