Free and protein-linked glycoinositolphospholipids in Trypanosoma cruzi

Two glycoinositol phospholipids (GIPL A and GIPL B) have been purified from epimastigotes of Trypanosoma cruzi at the logarithmic phase of growth (2 days). The GIPLs differ mainly in the lipid moiety and are similar to the lipopeptidophosphoglycan (LPPG) previously isolated from epimastigotes at the stationary phase (4-5 days). [3H]-palmitic acid was incorporated into 1-O-hexadecyl-2-O-palmitoylglycerol in GIPL A and into a sphinganine ceramide with palmitic acid and lignoceric acid as the fatty acids in GIPL B. The lipids could be released by incubation with phosphatidylinositol-specific phospholipase C (PI-PLC) or glycosylphosphatidylinositol phospholipase D (GPI-PLD) from rat serum. The oligosaccharides share the common core structure of the glycosylphosphatidilinositol (GPI) membrane anchors. Microheterogeneity was demonstrated, as well as substitution by galactose, which is mainly in the furanose configuration as was previously described for the LPPG. However, methylation analysis indicated that 20 percent of the galactose is present as terminal pyranose units. In infective trypomastigotes, [3H]-palmitic acid was incorporated into the anchor of the Tc-85 glycoprotein. The lipid cleaved by phospholipase C digestion was identified as 1-O-hexadecylglycerol and the main oligosaccharide has the structure of the conserved core of all GPI anchors. [3H]-palmitic acid-labelled Tc-85 released into the culture medium as membrane vesicles showed 80 percent resistance to the action of PI-PLC. However, after mild alkaline hydrolysis, part of the radioactivity was released by the enzyme

Evidence for the presence of ß-D-galactofuranosyl residues (1->3)-linked to a-D-mannopyranose on the cell membrane in all developmental stages of Trypanosoma cruzi

The lipopeptidophosphoglycan (LPPG) component isolated from epimastigote forms of Trypanosoma cruzi has antigenic properties. Using a rabbit antiserum aginst LPPG, specific for ß-D-galactofuranosyl residues (1-3)-linked to alfa-Dmannopyranose, we identified, by indirect immunofluorescence, the presence of epitopes containing ß-D-galactofuranosyl structures on the cell membrane of epimastigote, amastigote and trypomastigote forms of the parasite. The results demonstrade that all developmental stages of T. cruzi contain similar antigenic determinants on their cell body and flagellar membrane