GLYCOINOSITOL-PHOSPHOLIPID PROFILES OF 4 SEROTYPICALLY DISTINCT OLD-WORLD LEISHMANIA STRAINS

Glycoinositol-phospholipids (GIPLs) are the major glycolipid class and prominant surface antigens of leishmanial parasites. The GIPLs from f our serologically distinct Old World strains of Leishmania were charac terized to determine inter- and intraspecific differences in these gly colipids. These studies showed that: (1) the major GIPLs of Leishmania topica (LRC-L36) and Leishmania aethiopica (LRC-L495) belong to the a lpha-mannose-terminating GIPL series (iM2, iM3 and iM4) that are struc turally related to the glycosyl-phosphatidylinositol anchors of bo th the surface proteins and the abundant lipophosphoglycan (LPG). In cont rast, the GIPLs from two Leishmania major strains (LRC-L456 and LRC-L5 80) belong to the a-galactose-terminating GIPL series (GIPL-1, -2 and -3) that are more structurally related to the LPG anchor; (2) the GIPL profiles of the L. major strains differed in that a significant propo rtion of the GIPL-2 and -3 species (approximately 40% and 80%, respect ively) in LRC-L580 are substituted with a glucose-1-PO4 residue, while this type of substitution was not detected in LRC-L456; and (3) all t he GIPLs contained either an alkylacyl- or a lysoalkyl-phosphatidylino sitol lipid moiety. However, the alkyl chain compositions of different GIPLs within the same strain was variable. In L. major, the major GIP L species contained alkylacylglycerols with predominantly C-18:0 and C -24:0 alkyl chains, whereas the glucose-1-PO4-substituted GIPLs contai ned exclusively lysoalkyl-glycerols with C-24:0 alkyl chains. In L. tr opica, the major GIPL, iM2, contained predominantly C-24:0 alkyl chain s whereas the structurally related iM3 and iM4 GIPLs in this strain co ntained predominantly C-18:0 alkyl chains. In L. aethiopica all the GI PLs (iM2, iM3, iM4) contained C-18:0 alkyl chains. These data suggest that the synthesis of the GIPLs may occur in more than one subcellular compartment. The possibility that species-specific differences in the predominant surface glycan structures may modulate the interaction of the parasite with the insect and mammalian hosts is discussed.