CHARACTERIZATIONS OF PNEUMOCYSTIS-CARINII AND RAT LUNG LIPIDS - GLYCERYL ETHERS AND FATTY ALCOHOLS

Pneumocystis carinii carinii and rat lung phospholipids contained 3-6% 1-alkyl-2-acyl glycerols composed of the glyceryl ether species, 1-O- octadecyl glycerol (batyl alcohol), 1-O-octadec-9-enyl glycerol (selac hyl alcohol), 1-O-hexadecyl glycerol (chimyl alcohol), and 1-O-hexadec -9-enyl glycerol, Of the major phospholipid classes, phosphatidylinosi tol (PI) and phosphatidylserine contained the highest percentage of al kyl acyl glycerols, Methylprednisolone treatment caused an increase in alkyl acyl PI of rat lung lipids from 12% to 45%. As the PI concentra tion in lung phospholipids increases in rats treated with methylpredni solone, the increase in alkyl acyl PI was substantial; the proportions of alkyl acyl phosphatidylethanolamine and alkyl acyl lyse phosphatid ylcholine (PC) also increased. Pneumocystis phospholipids contained hi gher proportions of alkyl acyl PC than the phospholipids of the lungs from normal and immunosuppressed uninfected rats.<INF></INF> The glyce ryl ether compositions of P. carinii carinii PC and lyse PC were simil ar, which suggests that lyse PC in the organism is derived by phosphol ipase A<INF>2</INF> action on PC. This was not the case for PC and lys e PC of the lung controls. Analysis of the free fatty alcohols, precur sors of glyceryl ethers identified only saturated species in P. carini i carinii and rat lung controls. Thus, the introduction of a double bo nd in the alcohol moiety of glyceryl ethers occurs after formation of the ether linkage between fatty alcohol and the glyceryl backbone.