Enhanced accessory cell function by alveolar macrophages from patients infected with the human immunodeficiency virus: potential role for depletion of CD4+ cells in the lung.

Mononuclear phagocytes, including alveolar macrophages (AM), can be infected by the human immunodeficiency virus (HIV). Acting as accessory cells (AC), AM could infect CD4 lymphocytes through cell-to-cell contact and by inducing T cell proliferation, which increases lymphocyte susceptibility to infection. Using normal allogeneic T cells as responders, AM from infected individuals demonstrated an enhanced ability to stimulate a Con A and pokeweed mitogen lymphocyte proliferation assay compared with normal AM. Exogenous IL 1 enhanced the stimulation of a mitogen response by normal AM, but not from HIV-positive individuals, suggesting increased levels of this cytokine may explain the observed enhancement. However, increased IL 1 secretion by AM from HIV-infected patients could not be demonstrated, either in a bioassay or antigenically using an ELISA for IL-1 beta. Syncytia formation was observed when AM from asymptomatic HIV-positive individuals were cultured with normal T cells, suggesting viral transmission was occurring. Finally, in individual patients the stimulation of a mitogen response was inversely correlated with the CD4/CD8 ratio and total CD4 count, suggesting that enhanced AC function and CD4 cell depletion may be related in vivo. These findings indicate that enhanced AM accessory cell function is seen in HIV-infected individuals and could be a potential mechanism for CD4 cell depletion in the lung.

Mycobacterium avium-Mycobacterium intracellulare infection limited to the skin and lymph nodes in patients with AIDS.

Three patients with AIDS who were taking 3'-azido-3'-deoxythymidine (AZT) developed cutaneous abscesses from which Mycobacterium avium-Mycobacterium intracellulare was isolated. Culture of multiple blood samples and bone marrow aspirate from all three patients revealed that the infection was not disseminated. This is a rare form of presentation for this infection in AIDS patients. We speculate that the antiviral drug AZT was responsible for the localization of disease.

Pseudomonas testosteroni infections: eighteen recent cases and a review of the literature.

Pseudomonas testosteroni has been largely overlooked as a potential pathogen in humans. Ten cases of infection due to P. testosteroni were identified at a single metropolitan hospital in Texas during a three-year period. The organism was most often found in association with anatomic abnormalities of the gastrointestinal tract (six of 10 cases); perforation of the appendix was the commonest abnormality (five cases). The infections were more often polymicrobial (seven cases) than monomicrobial (three cases) and usually involved other organisms that, like P. testosteroni, are of colonic origin. Eight additional cases of infection involving P. testosteroni were reported by other hospitals in Texas during the same period. The organism was isolated from the peritoneal cavity in five of these cases. The results of these surveys suggest that infections of humans with P. testosteroni, while not common, are not as rare as might be predicted on the basis of the number of cases reported in the literature.