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J Immunol. 2006 Apr 15;176(8):4622-31.

MHC class II expression identifies functionally distinct human regulatory T cells.

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  • 1Laboratory of Molecular Immunology, Center for Neurologic Diseases, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA. callan@rics.bwh.harvard.edu

Abstract

It has been known for decades that circulating human CD4 cells can express functional MHC class II molecules that induce T cell nonresponsiveness with Ag presentation. Because there is significant expression of MHC class II (MHC-II) determinants (DR) on a subpopulation CD4+ CD25(high) regulatory T cells (Treg), we examined the function of CD4 cells expressing MHC-DR. We demonstrate that MHC-II expression on human CD4+ CD25(high) T cells identifies a functionally distinct population of Treg that induces early contact-dependent suppression that is associated with high Foxp3 expression. In striking contrast, MHC-II- CD4+ CD25(high) Treg induce early IL-4 and IL-10 secretion and a late Foxp3-associated contact-dependent suppression. The DR expressing CD25(high) Treg express higher levels of Foxp3 message and protein, compared with the DR- CD25(high) Treg population. Direct single-cell cloning of CD4+ CD25(high) Treg revealed that, regardless of initial DR expression, ex vivo expression of CD25(high), and not DR, predicted which clones would exhibit contact-dependent suppression, high levels of Foxp3 message, and an increased propensity to become constitutive for DR expression. Thus, the direct ex vivo expression of MHC-II in the context of CD25(high) identifies a mature, functionally distinct regulatory T cell population involved in contact-dependent in vitro suppression.

PMID:
16585553
[PubMed - indexed for MEDLINE]
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