Regulation of immunity in Trypanosoma cruzi infection.

Immunity to T. cruzi is complex, involving among other components, antibody production, CD4+ helper cells, CD8+ T cells as both regulators and effectors of immunity, and possibly, double-negative T cells. In addition, several of these components have been implicated in pathogenesis in the chronic infection. Although the immunosuppression observed in the infection seems quite severe, it also appears to provide for a sufficient level of immune responsiveness to control the infection in most hosts. At the same time, immunosuppression may provide the regulatory control necessary to prevent massive chronic pathogenesis in all hosts. Continued study of the relative roles of lymphocyte populations and the products they secrete in immunity and pathogenesis may provide the understanding necessary to enhance immunity to T. cruzi without the feared consequence of increased pathogenesis.