ウルソデオキシコール酸(UDCA)の免疫調節作用 ： 抗原提示に及ぼすUDCAの影響

Abstract

Effects of ursodeoxycholic acid (UDCA) on antigen presentation were investigated using monoclonal antigen presenting cells (APCs) and T cells. A mouse B cell lymphoma line expressing immunoglobulin M (IgM) specific for trinitrphenyl (TNP), a T hybridoma cell line specific for chicken ovalbumin (OVA) and TNP conjugated OVA (TNP-OVA) were used as APCs, T cells and an antigen, respectively. The T cells are known to release interleukin 2 (IL-2) and to obtain cytotoxic activities when they recognize the particular sequence of 17 amino acids of ovalubmin (OVA peptide) in the context of major histocompatibility gene product I-Aᵈ molecules. UDCA suppressed IL-2 production and cytotoxic activities of T cells. These suppressed T cell functions were also observed when the OVA peptide was used instead of TNP-OVA. UDCA, however, did not reduce the spontaneous expression of either MHC class Ⅱ molecules or TNP-specific IgM on the surface of APC. The capping and internalization of surface IgM during antigen exposure were not affected by UDCA. Furthermore, antigen-pulsed B cells in the presence of UDCA retained the ability of stimulating T cells. These results suggest that UDCA does not impair the function of antigen presenting cells and that UDCA may interfere with the recongnition of processed antigen by T cells in antigen presentation.