Apoptosis as a cause of T-cell unresponsiveness in experimental Chagas' disease.

A murine model of Chagas' disease induced by metacyclic forms of T. cruzi was used to evaluate T-cell function during infection. T-cell unresponsiveness to TcR;CD3 stimulation in vitro and lymphocyte activation in vivo occurred simultaneously. These paradoxical findings are discussed in the light of recent evidence that mature activated T cells become susceptible to TcR-mediated apoptosis. Activation-induced death in T cells from T. cruzi-infected mice has recently been demonstrated in this model. Evidence that TcR-induced death of activated T cells could be a cause for T-cell unresponsiveness in vitro and in vivo, as well as the possible molecular mechanisms involved, are discussed.