Analysis of peripheral blood mononuclear cell stimulated with pyruvate dehydrogenase complex, T-cell receptors from patients with primary biliary cirrhosis

Abstract

Progressive destruction of the intrahepatic bile ducts in patients with primary biliary cirrhosis (PBC) is thought to be mediated by cytotoxic T cells which recognize certain epitopes, such as the pyruvate dehydrogenase complex (PDC). To clarify the T-cell repertoire in PBC, we analyzed T-cell receptor (TCR) Vbeta-chain messages expressed in peripheral blood mononuclear cells (PBMCs) stimulated with PDC and in liver biopsy specimens. PBMCs from 12 PBC patients and 6 healthy controls were examined. The TCR Vbeta repertoires of unstimulated PBMCs and PBMCs stimulated with PDC purified from bovine heart were analyzed, using the reverse transcriptase-polymerase chain reaction (RT-PCR) and single-strand conformation polymorphism (SSCP). Liver biopsy specimens from 5 PBC patients were also analyzed. In the PBC patients, several different T-cell clones, some of which showed the same mobility, were evident in both the PDC-stimulated and unstimulated PBMCs, as demonstrated by SSCP analysis. In addition, TCR clonality of infiltrating lymphocytes in the liver was also observed in PBC patients, showing common clonal T-cell accumulation with that seen in PBMCs stimulated with PDC. These data indicate that common clonal T-cell accumulation specific for PDC may be present in both peripheral PBMCs and the liver of patients with PBC.

Pyruvate dehydrogenase specific T cells in primary biliary cirrhosis show restricted antigen recognition sites

“…Further, preferential usage of BV12 and conserved residues in the CDR3 region in liver‐infiltrating T cells of one out of two PBC patients has been described (16). More recently, Ochiai et al (20) provided evidence for clonal expansion of T cells in PBMC and liver biopsies by single strand conformation polymorphism (SSCP) analysis of the Vβ repertoire. The authors state that although no marked tendency towards T cell clonality in specific Vβ families was seen, clonal expansions were frequently observed for BV6, BV7 and BV13.2 (20).…”

“…More recently, Ochiai et al (20) provided evidence for clonal expansion of T cells in PBMC and liver biopsies by single strand conformation polymorphism (SSCP) analysis of the Vβ repertoire. The authors state that although no marked tendency towards T cell clonality in specific Vβ families was seen, clonal expansions were frequently observed for BV6, BV7 and BV13.2 (20). In addition, some of the T cell clonotypes showed the same mobility in SSCP gels in both unstimulated PBMC, and PBMC stimulated with PDC, suggesting an accumulation of common clonal T cells specific for the autoantigen.…”

“…Further studies analysed PDC‐specific T cell clones and described heterogeneity in the TCRBV usage (9) and the presence of an immuno‐dominant epitope within the PDC‐E2 component, comprising amino acids 163–176 in patients expressing the HLA‐DRB4*0101 haplotype (18, 19). Recently, a possible accumulation of clonal T cells specific for PDC in both peripheral blood mononuclear cells (PBMC) and in the liver of PBC patients has been shown (20). However, at present the molecular structures of the antigen‐recognition sites of PDC specific T cells are widely unknown.…”

A step to clarify the real target autoantigen in primary biliary cirrhosis

“…They revealed that T cells infiltrating the liver in PBC consisted of multiple clonotypes and that restricted T-cell clones accumulated in the liver were also present in peripheral blood lymphocytes. However, as Ochiai et al 1 point out in this issue of the Journal, there have been no reports on the analysis of TCR in T cells which have been stimulated with a plausible real autoantigen.…”

“…Thus, T-cell responses can be altered by molecular mimicry or by amino acid substitutions of MHC molecules or antigenic peptides, i.e., TCR ligands, and such peptide analogues can induce qualitative changes in T cells; T cell anergy, T cell antagonism, or changes in proliferative responses and lymphokine production 6,7 Consequently, the application of such altered peptides, in which pathogenic T cells can be selectively regulated without adverse effects such as systemic immunosupression, is considered to be a possibly promising approach to the treatment of autoimmune diseases. 17 The study by Ochiai et al 1 indicates the direction in which further studies on PBC should proceed. Clarification of these questions may provide new insights into the pathogenesis of PBC.…”