Broncho-alveolar lavage was performed to assess the degree of pulmonary lymphocytic alveolitis in 32 asymptomatic patients who were infected with the Human Immunodeficiency Virus (VIH). The patients were stages II and III of the CDC classification and the aim of the study was to determine the frequency, nature and prognostic role of the findings. 62.5% of the subjects (20/32) presented with a lymphocytic alveolitis which consisted predominantly of CD8 lymphocyte (64.3 +/- 3.5%), in the absence of an opportunistic infection or broncho-pulmonary tumours. Two sub-populations of alveolar CD8 were shown at comparable levels, a) sub-population CD8+D44+ (22.1 +/- 5%), in whom we showed the possession of cytotoxic activity in particular specific for VIH; b) sub-population CD8+CD57+ (19.6 +/- 3%) which we have shown to be capable in vitro of inhibiting the effector phase of cytotoxic activity of CD8+D44+ alveolar cells specific for VIH. In this group of 32 patients the occurrence of an alveolitis was not correlated with the usual prognostic factors of infection by VIH measured simultaneously with broncho-alveolar lavage (the level of CD4+ blood lymphocytes, and the beta 2-plasma microglobulins and the presence of p24 antigenaemia). In addition the level of CD4 lymphocytes supperior to 400/mm3 and of beta 2-microglobulins less then 3 mg/l whether a lymphocytic alveolitis was there or not confirmed the relatively poorly developed state of the VIH infection in these asymptomatic patients. Also the occurrence of a lymphocytic alveolitis did not seem to be linked to progression of the disease in the group of patients studied.(ABSTRACT TRUNCATED AT 250 WORDS)