Parasitic load increases and myocardial inflammation decreases in Trypanosoma cruzi-infected mice after inactivation of helper T cells.

In order to characterize the role played by CD4+ T lymphocytes in the immunopathology of acute Trypanosoma cruzi infection, we compared the numbers of blood and tissue parasites and the heart inflammatory reaction in normal and anti-CD4 antibody-treated C3H mice. Treatment of mice with anti-CD4 mAb during acute infection markedly inhibited T-helper-cell-dependent activities, as measured by peritoneal macrophage activation and immunoglobulin secretion by splenic B lymphocytes. After in vivo inactivation of helper T cells, the number of blood and tissue parasites significantly increased, while the inflammatory cellular infiltrates of heart muscles diminished. Our results indicate that CD4+ T lymphocytes play a dual role in the immunopathology of acute experimental Chagas' disease.