GLYCOSYLPHOSPHATIDYLINOSITOL-ANCHORED MUCIN-LIKE GLYCOPROTEINS ISOLATED FROM TRYPANOSOMA-CRUZI TRYPOMASTIGOTES INITIATE THE SYNTHESIS OF PROINFLAMMATORY CYTOKINES BY MACROPHAGES

Components of Trypanosoma cruzi able to induce the production of IL-12 and other proinflammatory cytokines by macrophages were identified, M urine inflammatory macrophages were cultured with live parasites or wi th cellular components from different developmental forms of T. cruzi (i.e., trypomastigotes, amastigotes, metacyclic trypomastigotes, and e pimastigotes), and the cytokine levels were measured after 24 and 48 h . Our results indicate that live trypomastigotes or live amastigotes ( but not five epimastigotes or live metacyclic trypomastigotes) as well as trypomastigote extracts (but not extracts derived from epimastigot es) induce IL-12 and TNF-alpha synthesis by macrophages. Such biologic al activity is enhanced in membrane preparations from trypomastigotes, Further enrichment of the trypomastigote-derived monokine-inducing fa ctor was obtained by solvent extraction and hydrophobic-interaction ch romatography, The resultant purified molecules are a family of closely related glycoconjugates with predominant species at 70 to 80 and 120 to 200 kDa. These molecules are composed of carbohydrate chains O-link ed to a polypeptide backbone that is anchored to the trypomastigote me mbrane via a glycosylphosphatidylinositol structure. The trypomastigot e-derived glycoconjugates are active in inducing cytokine synthesis by macrophages at concentrations of 100 ng/ml. These effects are highly potentiated by IFN-gamma. Mapping of the glycoconjugate molecules to c haracterize the structural requirements for macrophage activation sugg ested that nonsaturated acyl fatty acid chains and periodate-sensitive units from the glycosylphosphatidylinositol anchor are important elem ents for the infective trypomastigote form to initiate cytokine synthe sis by macrophages.