Published online before print July 8, 2008
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* JE 2448, "Cellules Dendritiques et Greffes," and
UFR des Sciences Pharmaceutiques, Université François-Rabelais de Tours, Tours, France
2 Correspondence: Université Francois-Rabelais de Tours, JE 2448, "Cellules Dendritiques et Greffes," 10 Bd Tonnelle, Tours, 37000, France. E-mail: lebranchu{at}med.univ-tours.fr
Depending on their degree of maturation, costimulatory molecule expression, and cytokine secretion, dendritic cells (DC) can induce immunity or tolerance. DC treated with mycophenolic acid during their maturation (MPA-DC) have a regulatory phenotype and may therefore provide a new approach to induce allograft tolerance. Purified CD4+ T cells stimulated in a human in vitro model of mixed culture by allogeneic MPA-DC displayed much weaker proliferation than T cells activated by mature DC and were anergic. This hyporesponsiveness was alloantigen-specific. Interestingly, T cells stimulated by MPA-DC during long-term coculture in four 7-day cycles displayed potent, suppressive activity, as revealed by marked inhibition of the proliferation of naive and preactivated control T cells. These regulatory T cells (Tregs) appeared to have antigen specificity and were contact-dependent. Tregs induced by MPA-DC were CD25+glucocorticoid-induced TNFR+CTLA-4+CD95+, secreted IL-5 and large amounts of IL-10 and TGF-β, and displayed enhanced forkhead box p3 expression. These results obtained in vitro demonstrate that human MPA-DC can induce allospecific Tregs that may be exploited in cell therapy to induce allograft tolerance.
Key Words: tolerance suppression T lymphocytes