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Journal of Parasitology Research
Volume 2012, Article ID 635873, 6 pages
Clinical Study

Evidence for T Cell Help in the IgG Response against Tandemly Repetitive Trypanosoma cruzi B13 Protein in Chronic Chagas Disease Patients

1Laboratory of Immunology, Heart Institute (InCor), School of Medicine, University of São Paulo, 05403-900 São Paulo, SP, Brazil
2Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, 05508-800 São Paulo, SP, Brazil
3Division of Clinical Immunology and Allergy, School of Medicine, University of São Paulo, 01246-903 São Paulo, SP, Brazil
4Institute for Investigation in Immunology (iii), INCT, 05403-900 São Paulo, SP, Brazil
5Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, MA 02142, USA
6Myocardiopathies Unit, Heart Institute (InCor), School of Medicine, University of São Paulo, 05403-900 São Paulo, SP, Brazil

Received 1 September 2011; Accepted 11 November 2011

Academic Editor: Mauricio M. Rodrigues

Copyright © 2012 Marcia Duranti et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The tandemly repetitive Trypanosoma cruzi B13 protein is an immunodominant antigen among Chagas disease patients. Such repetitive domains may behave as T-independent antigens. However, T cells can recognize B13 epitopes in an HLA class II-restricted fashion and could potentially provide cognate T cell help and boost antibody titers. We assessed whether the presence of HLA class II molecules able to present B13 epitopes to T cells could affect anti-B13 IgG levels in a cognate fashion, in both major clinical forms of chronic Chagas disease. We found no difference between anti-B13 IgG antibody levels between patients carrying HLA class II molecules associated to T cell responses or other alleles. The predominant anti-B13 IgG subclass was IgG1, with negligible IgG2, suggesting a T-dependent, noncognate help for antibody production. In addition, the finding of increased anti-B13 IgG levels in sera from CCC patients indicates that clinical presentation is associated with increased anti-B13 antibody levels.