Chagasic patients develop a type 1 immune response to Trypanosoma cruzi trans-sialidase

Infective forms of Trypanosoma cruzi, the parasite that causes Chagas' dise ase, express on their surface an enzyme denominated trans-sialidase (TS). T he present study was designed to evaluate the naturally acquired immune res ponses to a bacterial recombinant protein representing the catalytic domain of TS in chronically infected chagasic individuals. The cellular immune re sponse was measured by in-vitro T-cell proliferation and by interferon (INF )-gamma, interleukin (IL)-4 and IL-10 production in response to a whole-par asite homogenate and the recombinant protein. The peripheral blood mononucl ear cells of 78.6% of 28 chagasic patients responded to the recombinant pro tein as estimated by T-cell proliferation. With respect to cytokine product ion, 88% of the cells of the chagasic individuals produced IFN-gamma on sti mulation with the recombinant protein. In contrast, IL-4 or IL-10 were mini mally produced in response to TS. The cellular immune response was specific because most healthy individuals never exposed to T. cruzi failed to react with this recombinant protein. The plasma of 71.4% or 100% of chagasic pat ients had Ige antibodies as determined by ELISA or by the presence of TS in hibitory antibodies, respectively. We conclude that the catalytic domain of TS is recognized by IFN-gamma producing type I cells and antibodies in a l arge proportion of patients infected with T. cruzi.