ORIGINAL ARTICLE Natural CD4 + T-cell responses against Trypanosoma cruzi KMP-11 protein in chronic chagasic patients Adriana Cuellar 1 , Francia Rojas 1 , Natalia Bolan ˜os 2 , Hugo Diez 3 , Marı ´a del Carmen Thomas 4 , Fernando Rosas 5 , Victor Velasco 5 , Manuel Carlos Lo ´ pez 4 , John Mario Gonza ´lez 2 and Concepcio ´n Puerta 3 Trypanosoma cruzi kinetoplastid membrane protein-11 (KMP-11) is able to induce protective immunity in mice. In humans, T-cell immunity during Chagas disease has been documented using parasite antigens allowing the identification of specific CD8 + T cells. However, little is known about the CD4 + T-cell response during the evolution of the disease. In this paper, the induction of a natural CD4 + T-cell response against the KMP-11 protein in T. cruzi infected humans was studied to assess whether this parasite-derived protein could be processed, presented and detected as a major histocompatibility complex class II restricted epitope. The results show that helper T cells from 5 out of 13 chagasic patients specifically produced interferon-g after exposure to the KMP-11 antigen, whereas healthy donors and non-chagasic cardiopathic patients did not respond. This is the first description of T. cruzi KMP-11 protein recognition by CD4 + T cells in chronic chagasic patients. Immunology and Cell Biology (2009) 87, 149–153; doi:10.1038/icb.2008.76; published online 28 October 2008 Keywords: CD4 + T lymphocytes; Chagas disease; immune response; Trypanosoma cruzi Trypanosoma cruzi, a human hemoflagellate parasite, causes the Chagas disease, which affects 15 million people in 21 endemic countries with an annual incidence of 41200 cases around the world. 1 In Colombia, it is estimated that 700 000 people are infected and 23% of the population is at risk of contracting the disease with 30 000–40 000 new cases per year. 2 Chagas disease has a natural disease history that includes three different phases. The acute onset is solely seen in endemic areas with some clinical characteristics not often detected. Most people recovered from this phase and moved to the indeterminate phase where parasites persist in blood with no symptoms for at least 20 or 30 years. Some infected individuals develop a chronic disease indicating that their immune response is not capable of controlling the infection. This parasite persistence affects tissues, giving rise to local inflammatory lesions that are characteristic of the chronic phase with heart or visceral enlargement. Heart involvement could progress to a marked cardiomegaly, cardiac failure, severe arrhythmia and death. 3,4 The immune response plays a key role in controlling the infection but has also been implicated in the pathogenesis of the chronic disease. Several studies have reported that the kinetoplastid membrane protein-11 (KMP-11) is able to elicit both B- and T-cell lymphopro- liferation as well as cytotoxic responses. 5–10 Indeed, Maran ˜on et al. 6 showed that the immunization of HLA-A2/K b transgenic mice with the recombinant fusion protein encompassing the T. cruzi heat-shock protein of 70 kDa (HSP70) and KMP-11 sequences induces a cytotoxic response against human cells expressing the KMP-11 protein. An immunodominant HLA-A*0201 restricted cytotoxic epitope, termed K1, was identified and located between amino acids 4–12 of the KMP- 11 protein. Moreover, mice immunized with the chimerical gene that codifies for the KMP-11 and HSP70 proteins produced antibodies and CTL response that induced protection after parasite challenge. 8 Earlier, it was shown in our group that CD8 + T cells from chagasic patients recognized the K1 peptide in the context of the HLA-A*0201 and specifically secreted interferon-g (IFNg), suggesting that the K1 peptide is efficiently processed, presented and recognized by CD8 + T lymphocytes during the natural course of the Chagas disease. 11 In contrast, information about specific CD4 + T cells in infected humans is scarce. On the basis of previous results in the murine model, it is clear that the coordinated activation of both CD4 + and CD8 + T cells are essential for infection control. 12 The aim of this study is to identify whether the KMP-11 protein has the potential to enter in the major histocompatibility complex class II processing and presentation pathway to further characterize the CD4 + T-cells response during the infection. The presence of IFNg or interleukin Received 10 January 2008; revised 18 September 2008; accepted 21 September 2008; published online 28 October 2008 1 Grupo de Inmunobiologı ´a y Biologı ´a Celular, Departamento de Microbiologı´a, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogota ´ , Colombia; 2 Grupo de Ciencias Ba ´ sicas Me ´ dicas, Universidad de los Andes, Bogota ´ , Colombia; 3 Laboratorio de Parasitologı ´a Molecular, Departamento de Microbiologı ´a, Pontificia Universidad Javeriana, Bogota ´, Colombia; 4 Departamento de Biologı ´a Molecular, Instituto de Parasitologı ´a y Biomedicina Lo ´pez Neyra, CSIC, Granada, Spain and 5 Fundacio ´n Clı´nica Abood Shaio, Bogota ´, Colombia Correspondence: Dr C Puerta, Laboratorio de Parasitologı ´a Molecular, Departamento de Microbiologı´a, Facultad de Ciencias, Pontificia Universidad Javeriana, Carrera 7a No 43-82, Edificio 52, Oficina 608, Bogota ´, Distrito capital 1, Colombia. E-mail: cpuerta@javeriana.edu.co Immunology and Cell Biology (2009) 87, 149–153 & 2009 Australasian Society for Immunology Inc. All rights reserved 0818-9641/09 $32.00 www.nature.com/icb