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Mediators of Inflammation
Volume 2014, Article ID 636039, 10 pages
http://dx.doi.org/10.1155/2014/636039
Research Article

Involvement of Different CD4+ T Cell Subsets Producing Granzyme B in the Immune Response to Leishmania major Antigens

1Laboratory of Transmission, Control, and Immunobiology of Infections-LR11IPT02, Pasteur Institute of Tunis, 13 Place Pasteur, 1002 Tunis, Tunisia
2University of Tunis El Manar, 1068 Tunis, Tunisia
3Department of Pathology, Charles Nicolle Hospital, Boulevard 9 Avril 1938, 1006 Tunis, Tunisia

Received 4 April 2014; Revised 10 June 2014; Accepted 10 June 2014; Published 2 July 2014

Academic Editor: Mauricio Martins Rodrigues

Copyright © 2014 Ikbel Naouar 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.

Abstract

The nature of effector cells and the potential immunogenicity of Leishmania major excreted/secreted proteins (LmES) were evaluated using peripheral blood mononuclear cells (PBMCs) from healed zoonotic cutaneous leishmaniasis individuals (HZCL) and healthy controls (HC). First, we found that PBMCs from HZCL individuals proliferate and produce high levels of IFN-γ and granzyme B (GrB), used as a marker of activated cytotoxic T cells, in response to the parasite antigens. IFN-γ is produced by CD4+ T cells, but unexpectedly GrB is also produced by CD4+ T cells in response to stimulation with LmES, which were found to be as effective as soluble Leishmania antigens to induce proliferation and cytokine production by PBMCs from immune individuals. To address the question of regulatory T cell (Tregs) involvement, the frequency of circulating Tregs was assessed and found to be higher in HZCL individuals compared to that of HC. Furthermore, both CD4+CD25+ and CD4+CD25 T cells, purified from HZCL individuals, produced IFN-γ and GrB when stimulated with LmES. Additional experiments showed that Tregs were involved in GrB production. Collectively, our data indicate that LmES are immunogenic in humans and emphasize the involvement of CD4+ T cells including activated and regulatory T cells in the immune response against parasite antigens.