We showed previously that cecal bacterial Ag (CBA)-specific CD4+ T cells induce colitis when transferred into SCID mice. The purpose of this study was to generate and characterize CBA-specific regulatory T cells in C3H/HeJBir (Bir) mice. CD4+ T cells were stimulated with CBA-pulsed APC in the presence of IL-10 every 10-14 days. After four or more cycles, these T cells produced high levels of IL-10, low levels of IL-4 and IFN-γ, and no IL-2, consistent with the phenotype of T regulatory-1 (Tr1) cells. Bir Tr1 cells proliferated poorly, but their proliferation was dependent on CD28-B7 interactions and was MHC class II-restricted. Transfer of Bir Tr1 cells into SCID mice did not result in colitis, and cotransfer of Bir Tr1 T cells with pathogenic Bir CD4+ Th1 cells prevented colitis. Bir Tr1 cells inhibited proliferation and IFN-γ production of a CBA-specific Th1 cell line in vitro. Such inhibition was partly due to IL-10 and TGFβ1, but cognate interactions with either APCs or Th1 cells were also involved. Normal intestinal lamina propria CD4+ T cells had Tr1-like activity when stimulated with CBA-pulsed APCs. We conclude that CD4+ T cells with the properties of Tr1 cells are present in the intestinal lamina propria and hypothesize that these cells maintain intestinal immune homeostasis to the enteric flora.
ASJC Scopus subject areas
- Immunology and Allergy