Regulation of murine chronic colitis by CD4+CD25- programmed death-1+ T cells

Abstract

Naturally arising CD4+CD25+ regulatory T (TR) cells are engaged in the maintenance of self tolerance and prevention of autoimmune diseases. However, accumulating evidence suggests that a fraction of peripheral CD4+CD25- T cells also possesses regulatory activity. Programmed death-1 (PD-1) is a new member of the CD28/CTLA-4 family, which has been implicated in the maintenance of peripheral self tolerance. Here, we identified a subpopulation of CD4+CD25-PD-1+ T cells in the spleen of naive mice that constitutively expressed CTLA-4 and FoxP3 and was hypoproliferative in response to anti-CD3 antibody stimulation in vitro. However, the CD4+CD25-PD-1+ T cells uniquely produced large amounts of IL-4 and IL-10 in response to anti-CD3 and anti-CD28 mAb stimulation, unlike the CD4+CD25+ TR cells. The CD4+CD25-PD-1+ T cells exhibited a suppressor activity against the proliferation of anti-CD3 antibody-stimulated CD4+CD25-PD-1- T cells in vitro, which was partially abrogated by anti-CTLA-4 mAb, but not by anti-IL-10 or anti-PD-1 mAb. Remarkably, the CD4+CD25-PD-1+ T cells inhibited the development of colitis induced by adoptive transfer of CD4+CD45RBhigh T cells into C.B17-scid/scid mice, albeit to a lesser extent than CD4+CD25+ TR cells, in a CTLA-4-dependent manner. These results indicate that the CD4+CD25-PD-1+ T cells contain substantial amounts of TR cells that are involved in the maintenance of peripheral tolerance. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.