FUNCTIONAL IMPAIRMENT OF BRONCHOALVEOLAR LAVAGE PHOSPHOLIPIDS IN EARLY PNEUMOCYSTIS-CARINII PNEUMONIA IN RATS

Surfactant abnormalities may contribute to the impairment of gas excha nge observed in Pneumocystis carinii pneumonia. Analysis of rat bronch oalveolar ravage (BAL) lipid extracts from normal controls, steroid co ntrols, trimethaprim-sulfamethoxazole (TMP-SMX) controls, TMP-SMX/P. c arinii pneumonia controls, and P. carinii pneumonia animals reveal sim ilar total phospholipid and total protein levels. However, there was a marked reduction in phosphatidylglycerol (PG) from the BAL of P. cari nii pneumonia rats as compared with control animals, with a decrease f rom 4.91 +/- 1.29 nmol/mg protein to 0.46 +/- 0.57 nmol/mg protein (p < 0.05) and a decrease, as a percent of total phospholipids, from 7.7% +/- 0.88% to 0.91% +/- 0.59% (p < 0.001). Furthermore, in vitro surfa ce activities of BAL lipid extracts from control and P. carinii pneumo nia rats revealed minimum surface tension increases from 9.38 +/- 1.71 mN/m in controls to 16.36 +/- 0.83 mN/m in P. carinii pneumonia rats (p < 0.05) and likewise maximum surface tension increases from 22.14 /- 4.34 mN/m to 38.57 +/- 2.07 mN/m (p < 0.01). Of interest, the surfa ce activity of PG-deficient P. carinii pneumonia BAL lipid extracts is completely restored to that of normal controls by the addition of exo genous PG. These findings suggest that a functionally abnormal surfact ant occurs in P. carinii pneumonia and that this may account, in part, for the impairment of gas exchange observed in this disorder.