Increased Indoleamine 2,3-Dioxygenase Expressing CD11c+CD11b+Dendritic cells in Oral Tolerance to Type II Collagen

Abstract

Objective: Indoleamine 2, 3-dioxygenase (IDO), an immuno suppression enzyme, is one of the initial and rate-limiting enzymes involved in the catabolism of the essential amino acid tryptophan. IDO inhibits T cell proliferation, induces T cell apoptosis, and plays a fundamental role in autoimmunity and allergy. We investigated which subtype of dendritic cells (DCs) is involved in IDO expression and the generation of regulatory T cells during the induction of oral tolerance in type II collagen-induced arthritis (CIA). Methods: Type II Collagen was fed to DBA/1J mice before immunization. Changes in DC subtypes and induction of regulatory T cell in orally tolerized CIA mice were analyzed. Whether the effect of DC subtype was modulated by the IDO expression, was determined by flow cytometry (FACs) and confocal microscopy. Results: IDO expression of CD11c ＋ DCs was higher in orally tolerized CIA mice than in