Abstract
C3H mice infected with Leishmania amazonensis develop persistent, localized lesions with high parasite loads. During infection, memory/effector CD44hiCD4+ T cells proliferate and produce IL-2, but do not polarize to a known effector phenotype. Previous studies have demonstrated IL-12 is insufficient to skew these antigen-responsive T cells to a functional Th1 response. To determine the mechanism of this IL-12 unresponsiveness, we used an in vitro assay of repeated antigen activation. Memory/effector CD44hiCD4+ T cells did not increase proliferation in response to either IL-2 or IL-12, although these cytokines upregulated CD25 expression. Neutralization of IL-2 enhanced CD4+ T cell proliferation in response to IL-12. This cross-regulation of IL-12 responsiveness by IL-2 was confirmed in vivo by treatment with anti-IL-2 antibodies and IL-12 during antigen challenge of previously infected mice. These results suggest that during chronic infection with L. amazonensis, IL-2 plays a dominant, immunosuppressive role independent of identifiable conventional Treg cells.
Original language | English (US) |
---|---|
Pages (from-to) | 32-39 |
Number of pages | 8 |
Journal | Cellular Immunology |
Volume | 270 |
Issue number | 1 |
DOIs | |
State | Published - 2011 |
Externally published | Yes |
Keywords
- IL-12
- IL-2
- Leishmania
- T cell
- Tolerance
ASJC Scopus subject areas
- Immunology