Glycoinositol-phospholipid profiles of four serotypically distinct Old World <em>Leishmania </em>strains

Glycoinositol-phospholipids (GIPLs) are the major glycolipid class and prominant surface antigens of leishmanial parasites. The GIPLs from four serologically distinct Old World strains of Leishmania were characterized to determine inter- and intraspecific differences in these glycolipids. These studies showed that: (1) the major GIPLs of Leishmania topica (LRC-L36) and Leishmania aethiopica (LRC-L495) belong to the a-mannose-terminating GIPL series (iM2, iM3 and iM4) that are structurally related to the glycosyl-phosphatidylinositol anchors of both the surface proteins and the abundant lipophosphoglycan (LPG). In contrast, the GIPLs from two Leishmania major strains (LRC-L456 and LRC-L580) 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 proportion of the GIPL-2 and -3 species (approximately 40% and 80%, respectively) in LRC-L580 are substituted with a glucose-1-PO residue, while this type of substitution was not detected in LRC-L456; and (3) all the GIPLs contained either an alkylacyl- or a lysoalkyl-phosphatidylinositol lipid moiety. However, the alkyl chain compositions of different GIPLs within the same strain was variable. In L. major the major GIPL species contained alkylacylglycerols with predominantly C(18:0) and C(24:0) alkyl chains, whereas the glucose-1-PO -substituted GIPLs contained exclusively lysoalkyl-glycerols with C(24:0) alkyl chains. In L. tropica the major GIPL, iM2, contained predominantly C(24:0) alkyl chains whereas the structurally related iM3 and iM4 GIPLs in this strain contained predominantly C(18:0) alkyl chains. In L. aethiopica all the GIPLs (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