Loss of suppressor activity in the serum of mice infected with Trypanosoma cruzi.

Previous work from this laboratory documented the presence of a suppressor substance in the serum of mice infected with Trypanosoma cruzi. Currently, however, we have been unable to demonstrate the presence of this suppressor factor, although infected mice were still profoundly suppressed in their ability to respond to SRBC, and suppressor cells were present in the spleens of these animals. Strains of T. cruzi other than the one presently in use in our laboratory gave similar results. Several possible explanations for our inability to demonstrate the presence of the suppressor factor in sera are discussed.