Extracellular ATP induces cell death in CD4+/CD8+ double-positive thymocytes in mice infected with Trypanosoma cruzi

In the acute phase of Trypanosoma cruzi infection, there is dramatic atrophy of the thymus. However, the pathways involved in this change have not yet been identified. This event is mainly characterized by a massive loss of cortical CD4(+)/CD8(+) double-positive cells, but also by other structural and functional alterations in the organ. A number of molecules, including extracellular ATP, have been suggested to play a role in the selective processes that take place in the thymus. ATP and analogues trigger many different cellular responses in thymocytes and other cell types, such as the opening of plasma membrane cation channels and a pore that may induce cell death. Herein, we investigated the possible involvement of extracellular ATP in thymus atrophy induced by infection with T. cruzi. We observed that ATP induces an increase in plasma membrane permeabilization and cellular death in CD4(+)/CD8(+) double-positive thymocytes collected from infected mice during the atrophy phase. No differences were observed prior to the atrophy phase or during the chronic phase. Our results indicate that P2Z/P2X(7) receptors may play a central role in thymus atrophy during T. cruzi infection. (C) 2003 Published by Editions scientifiques et medicales Elsevier SAS.