Phenotypic analysis of bronchoalveolar lavage lymphocytes from acquired immunodeficiency patients with and without Pneumocystis carinii pneumonia.

A study was performed to reveal possible differences in lymphocyte subpopulations from bronchoalveolar lavage (BAL) of acquired immunodeficiency patients with and without Pneumocystis carinii pneumonia. Forty-one consecutive human immunodeficiency virus-seropositive patients were studied. Pneumocystis carinii infection was detected in the BAL fluid from 18 patients. The BAL lymphocyte subpopulations were determined by surface marker analysis with the immunoperoxidase slide assay. No significant differences in the percentage of CD4+ and CD8+ lymphocytes were found between the two groups. The percentage of CD57+ natural killer (NK) cells was significantly higher in the Pneumocystis carinii-negative group than in the -positive group. Since NK cells protect from microbial infections, it is conceivable that the loss of CD57+ NK cells may be one of the phenomena leading to the immunodeficiency state that underlies the pulmonary complications characteristic of the acquired immunodeficiency syndrome.