A CD4+ TH2 cell line isolated from mice chronically infected withTrypanosoma cruzi induces IgG2 polyclonal responsein vivo

Abstract

In our study we describe further characteristics of a CD4⁺ T cell line (G‐05) isolated from lymph nodes of C3H/HeJ mice chronically infected with Trypanosoma cruzi. This T cell line secreted lymphokines such as interleukin (IL)4 and IL 5 and could be defined as a T_H2 type of helper T cells. By passive transferinto naive mice, the G‐05 line was able to induce a polyclonal B cell activation in the spleen. This splenic B cell activation was quite similar to that seen in chronically T. cruzi‐infected animals, where the isotypic pattern presents a large increase of IgG_2a and IgG_2b isotypes. Moreover, it was possible to reproduce this kind of polyclonal B cell activation in vivo, with the supernatant of G‐05 T cells cultured in the presence of T. cruzi extract, accessory cells andexogenous IL2. Analysis of this supernatant showed the presence of large amounts of IL 4,IL 5, IL 3 and IL 6 but not of interferon‐γ, and residual IL 2 activity was not significant. These results suggest that the G‐05 T cells considered as T_H2 cells on the basis of their lymphokine production are involved in the development of the in vivo polyclonal B cell activation in T. cruzi infection.