title: Dynamics of Lymphocyte Populations during Trypanosoma cruzi Infection: From Thymocyte Depletion to Differential Cell Expansion/Contraction in Peripheral Lymphoid Organs.
abstract: The comprehension of the immune responses in infectious diseases is crucial for developing novel therapeutic strategies. Here, we review current findings on the dynamics of lymphocyte subpopulations following experimental acute infection by Trypanosoma cruzi, the causative agent of Chagas disease. In the thymus, although the negative selection process of the T-cell repertoire remains operational, there is a massive thymocyte depletion and abnormal release of immature CD4(+)CD8(+) cells to peripheral lymphoid organs, where they acquire an activated phenotype similar to activated effector or memory T cells. These cells apparently bypassed the negative selection process, and some of them are potentially autoimmune. In infected animals, an atrophy of mesenteric lymph nodes is also observed, in contrast with the lymphocyte expansion in spleen and subcutaneous lymph nodes, illustrating a complex and organ specific dynamics of lymphocyte subpopulations. Accordingly, T- and B-cell activation is seen in subcutaneous lymph nodes and spleen, but not in mesenteric lymph nodes. Lastly, although the function of peripheral CD4(+)CD8(+) T-cell population remains to be defined in vivo, their presence may contribute to the immunopathological events found in both murine and human Chagas disease.
authors.affiliation: Laboratory on Thymus Research, Oswaldo Cruz Institute, Oswaldo Cruz Foundation, 21045-900 Rio de Janeiro, RJ, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Morrot
authors.forename: Juliana
authors.initials: J
authors.lastname: Barreto de Albuquerque
authors.forename: Luiz Ricardo
authors.initials: LR
authors.lastname: Berbert
authors.forename: Carla Eponina
authors.initials: CE
authors.lastname: de Carvalho Pinto
authors.forename: Juliana
authors.initials: J
authors.lastname: de Meis
authors.forename: Wilson
authors.initials: W
authors.lastname: Savino