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*Laboratory of Molecular Biology of Chagas' Disease (LaBMECh), Institute for Genetic Engineering and Molecular Biology (INGEBI), CONICET, and Center of Applied Genomics (Centro de Genomica Aplicada, CeGA)-UBA, Buenos Aires, Argentina;
Deutsches Rheumaforschungszentrum, Berlin, Germany;
División de Cardiología, Hospital Fernández, Buenos Aires, Argentina; and
División Patología, Instituto de Cardiología y Cirugía Cardiovascular Fundación Favaloro, Buenos Aires, Argentina
Patients chronically infected with Trypanosoma cruzi develop chronic Chagas' heart disease (cChHD). Their Ab response is suspected to be involved in the cardiac pathogenesis. Reactivity of serum Abs from these patients has been extensively studied but little is known about the diversity of the in vivo IgG repertoire. We analyzed 125 variable H chain (VH) genes and compared it to repertoires from healthy individuals, and patients with autoimmune processes and other infections. VH were from plasma cells isolated from heart tissue of three cChHD patients and from a Fab combinatorial library derived from bone marrow of another cChHD patient. The role of the parasite in shaping the Ab repertoire was assessed analyzing VH genes before and after panning against T. cruzi Ag. Among recovered VH genes, a significantly increased representation of VH4 was observed. Plasma cells at the site of cardiac infiltration showed an increased VH1 usage. CDR3 lengths were similar to the ones found in the healthy repertoire and significantly shorter than in other infections. VH derived from anti-T. cruzi Fab and plasma cells showed a higher proportion of hypermutated genes, 46.9% and 43.75%, respectively, vs 30.9% of the cChHD patient repertoire, pointing to the role of parasite Ags in the shaping of the humoral response in Chagas' disease. No histological evidence of germinal center-like structures was observed in heart tissue. In accordance, VH analysis of heart plasmocytes revealed no evidence of clonal B cell expansion, suggesting that they migrated into heart tissue from secondary lymphoid organs.
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1 This work was supported mainly by an International Research Grant from the Howard Hughes Medical Institute (Chevy Chase, MD). This research was also supported by grants from the World Health Organization/Special Program for Research and Training in Tropical Diseases; the Argentinean National Council for Science and Technology (CONICET), the University of Buenos Aires, Health and Social Action Office-Fellowship Ramón Carrillo-Arturo Oñativia, the National Agency of Scientific and Technological Promotion (FONCYT BID 1201/OC-AR, PICT 05-06802, PICT 01-14389, and BID 1728/OC-AR PICT 2006 No. 2439), and partially supported by the Bunge y Born Foundation of Argentina. This work was also supported by the European Union EU program (ARG/B7-3011/94/28A) and the Deutsche Rheuma ForschungsZentrum is supported by the Berlin Senate of Research and Education.
2 Address correspondence and reprint request to Dr. Mariano J. Levin, Laboratorio de Biología Molecular de Chagas', Institute for Genetic Engineering and Molecular Biology, Vuelta de Obligado 2490, 2nd Floor, 1428 Ciudad de Buenos Aires, Argentina. E-mail adress: mlevin{at}dna.uba.ar
3 Abbreviations used in this paper: cChHD, chronic Chagas' heart disease; IDC, idiopathic dilated cardiomyopathy; DS, denaturing solution; GC, germinal center; FDC, follicular dendritic cells; scFv, single chain variable fragment; VH, variable heavy chain; CDRH, complementary determining regions of heavy genes; FR, framework regions; PBL, peripheral blood lymphocytes.
4 The online version of this article contains supplemental material.
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