CD4 and parasitic infectious disease: In this work, we found that the adoptive transfer of CD4+CD25+FOXP3+ T cells from rSSP4- (a recombinant Trypanosoma cruzi amastigote derived protein, previously shown to have immunomodulatory properties on macrophages) immunized BALB/c donors into syngenic recipients simultaneously with T. cruzi challenge reduces cardiac inflammation and prolongs hosts' survival but increases blood parasitemia and parasite loads in the heart.