Analysis of T cell repertoire in the liver of patients with chronic hepatitis C

Abstract

Many T cells infiltrate into the liver of patients with chronic hepatitis C (CH-C). They are believed to play a crucial role in the immunopathogenesis of hepatic inflammation, but their clonality and specificity are unknown. The aim of this study was to clarify the characteristics of these T cells. We analysed the complementarity-determining region (CDR)3 size lengths of T cell receptor (TCR) beta-chains by size spectratyping, and determined the sequences of Vbeta CDR3 after subcloning Vbeta-specific polymerase chain reaction products. Spectratyping showed clonal expansions in all liver specimens, most of which showed more than two T cell clones. Moreover, many non-clonal T cells also accumulated in the liver. Clonality of the T cells suspected by spectratyping was confirmed by CDR3 sequencing. Although the sequences revealed no whole CDR3-shared clones among different patients, some common motif sequences were observed. Our data suggest that T cells are stimulated by several hepatitis C virus (HCV) epitopes, then accumulate in the liver of CH-C patients. Shared motifs of expanded T cell clones suggest that they might recognize the same regions of HCV peptides, but have differences due to HCV peptide mutational changes. These clones might also interact with non-clonal T cells and play a crucial role in the immunopathogenesis of CH-C.

Fig. 1

T cell receptor (TCR) Vβ size spectratypes of liver-infiltrating T lymphocytes (LIT) in case 8. The fluorescent labelled polymerase chain reaction products were analysed in an automated sequencer with GeneScan software. The abscissa shows CDR3 size length (base pairs) and ordinate shows fluorescence intensity. Some TCR Vβ CDR3 size spectratyping patterns of LIT show single or double peaks but others show multipeaks. Vβ which are not shown in figure have no or very small peaks. Vβ, variable region β.

Fig. 2

T cell receptor (TCR) Vβ12 size spectratypes of peripheral blood lymphocytes (PBL) (a) and liver-infiltrating T lymphocytes (LIT) (b) in cases 2, 6, 7, 8 and 9. The fluorescent labelled polymerase chain reaction products were analysed in an automated sequencer with GeneScan software. The numbers on the upper bars are base-pair sizes of CDR3 segments. TCR Vβ CDR3 size spectratyping patterns of LIT show single or double peaks but those of PBL show multipeaks. Vβ, variable region β.