Humoral suppression in Trypanosoma cruzi infection in relation to the timing of antigen presentation.

(CBA x C57 B1/10)F1 mice infected intraperitoneally with 100 parasites of Trypanosoma cruzi strain Y developed an infection with acute and chronic phases. Humoral suppression to sheep red blood cells was evident in both phases but enhancement of the response was achieved only at the beginning of the infection. A mitogen secreted by the parasite could explain both phenomenons.