Enhancement of delayed-type hypersensitivity to Trypanosoma cruzi in mice treated with Mycobacterium bovis BCG and cyclophosphamide.

C57BL/10J mice treated with Mycobacterium bovis BCG and cyclophosphamide were immunized with disrupted epimastigotes or with living blood trypomastigotes from Trypanosoma cruzi and assayed for delayed hypersensitivity by footpad testing with epimastigote antigens. Enhanced and lasting reactions were observed in mice pretreated with BCG or cyclophosphamide or both and immunized with epimastigotes. Whereas BCG pretreatment clearly reduced the mortality rates of mice immunized with living blood forms, no enhancement of the delayed hypersensitivity responses was observed in animals treated with BCG or cyclophosphamide or both before infection. The production of high levels of delayed hypersensitivity in the absence of infection and its adoptive transfer with cells could help to evaluate the participation of cell-mediated immunity in the protection against T. cruzi.