Lytic anti-α-galactosyl antibodies from patients with chronic Chagas' disease recognize novel O-linked oligosaccharides on mucin-like glycosyl-phosphatidylinositol-anchored glycoproteins of Trypanosoma cruzi

摘要: Sera of patients with chronic Chagas' disease (American trypanosomiasis) contain elevated levels anti-alpha-galactosyl antibodies that are lytic to Trypanosoma cruzi. The T. cruzi trypomastigote F2/3 antigen complex recognized by these runs as a broad smear on SDS/PAGE [Almeida, Krautz, Krettli and Travassos (1993) J. Clin. Lab. Anal. 7, 307-316]. Treatment cells bacterial phosphatidylinositol-specific phospholipase C (PI-PLC) abolished most their reactivity Chagas'-disease ((Chagasic, Ch) (anti-Gal). complex, purified solvent extraction hydrophobic-interaction chromatography, contained 60% carbohydrate weight substantial amounts Thr, Ser, Glx, Asx, Gly, Ala Pro, but relatively few hydrophobic amino acids. presence myoinositol, ethanolamine 1-O-hexadecylglycerol suggested the glycosyl-phosphatidylinositol membrane anchors. This was confirmed PI-PLC treatment, which rendered molecules hydrophilic reactive anti-(cross-reacting determinant) antibodies. majority GlcNAc content antigens found at reducing termini oligosaccharides in O-glycosidic linkage Thr residues. These O-linked could be released beta-elimination mild hydrazinolysis. smallest oligosaccharitol Ch anti-Gal Gal alpha 1-3Gal beta 1-4GlcNAcol (where GlcNAcol is N-acetyl-glucosaminitol). Several other Gal-containing oligosaccharitols were observed, branched 4,6-di-O-substituted termini. About half total bind immobilized anti-Gal, none them bound isolated from normal human sera. data suggest specificities quite different natural Therefore, novel highly immunogenic under conditions infection targets for anti-Gal.