LIPID TRANSFER FROM HUMAN EPITHELIAL-CELLS TO PNEUMOCYSTIS-CARINII IN-VITRO

Pneumocystis carinii lipids are similar to host lipids, but it is not known if some of these lipids are acquired from host cells. The abilit y of P. carinii to incorporate a fluorescent fatty acid analogue (Bodi py-C-12) was analyzed, the metabolism of the incorporated lipid by P. carinii was characterized, and lipid transfer from human alveolar epit helial cells (A549) to P. carinii was investigated. Both P. carinii an d A549 cells incorporated exogenous Bodipy-C-12 in a concentration-dep endent manner. Biochemical analysis of labeled P. carinii revealed inc orporation of Bodipy-C-12 into complex lipid classes. Incubation of un labeled P. carinii with Bodipy-C-12-labeled A549 cells demonstrated li pid transfer to P. carinii, a process facilitated by attachment. These data suggest that P. carinii can incorporate and modify an exogenous fluorescent lipid. The observed transfer of lipid from A549 cells to P . carinii provides important insight into the interaction of this orga nism with alveolar epithelial cells.