ABNORMAL LIPID-COMPOSITION OF BRONCHOALVEOLAR LAVAGE FLUID OBTAINED FROM INDIVIDUALS WITH AIDS-RELATED LUNG-DISEASE

Surfactant lipids are not only important to the physiologic function o f the lungs, but may also influence disease processes like Pneumocysti s pneumonia, in which the interaction of host-defense cells with patho gen occurs within the confines of the surfactant-rich alveolar hypopha se. In the present studies the lipid profile of bronchoalveolar lavage fluid (BALF) was characterized in subjects with AIDS-related lung dis eases including Pneumocystis pneumonia. BALF lipid and total protein m easurements were made in 43 subjects with acquired immune deficiency s yndrome (AIDS)-related lung disease and compared with those made in 50 normal human immunodeficiency virus (HIV)-seronegative controls. The AIDS patient samples contained significantly greater amounts of total cholesterol, phosphatidylglycerol (PG), and protein than the control s amples; in contrast to previous observations in rodent P. carinii infe ction, no differences were seen in total phospholipid (PL) or phosphat idylcholine (PC) in the two groups. The proportions of several of thes e lipids were deranged in BALF obtained from the patient group: PG/PL and PC/cholesterol differed significantly from normal samples. In the subset of patients with AIDS-related Pneumocystis pneumonia, no correl ation was apparent between discrete BALF lipids and clinical indices r eflective of disease severity. Using these measurements to approximate the lipid composition of the alveolar microenvironment in AIDS-relate d lung disease, we performed experiments in which normal human alveola r macrophages were exposed to exogenous liposomal lipids and then chal lenged with P. carinii. The ingestion but not binding of P. carinii by macrophages was diminished as a result of lipid exposure. These studi es document a unique abnormality in BALF lipids that may have an impor tant impact on the pathobiology of AIDS-related lung disease.