title: Compartmentalization of T lymphocytes to the site of disease: intrahepatic CD4+ T cells specific for the protein NS4 of hepatitis C virus in patients with chronic hepatitis C.
abstract: The adult liver is an organ without constitutive lymphoid components. Therefore, any intrahepatic T cell found in chronic hepatitis should have migrated to the liver after infection and inflammation. Because of the little information available on the differences between intrahepatic and peripheral T cells, we used recombinant proteins of the hepatitis C virus (HCV) to establish specific T cell lines and clones from liver biopsies of patients with chronic hepatitis C and compared them with those present in peripheral blood mononuclear cells (PBMC). We found that the protein nonstructural 4 (NS4) was able to stimulate CD4+ T cells isolated from liver biopsies, whereas with all the other HCV proteins we consistently failed to establish liver-derived T cell lines from 16 biopsies. We then compared NS4-specific T cell clones obtained on the same day from PBMC and liver of the same patient. We found that the 22 PBMC-derived T cell clones represent, at least, six distinct clonal populations that differ in major histocompatibility complex restriction and response to superantigens, whereas the 27 liver-derived T cell clones appear all identical, as further confirmed by cloning and sequencing of the T cell receptor (TCR) variable and hypervariable regions. Remarkably, none of the PBMC-derived clones has a TCR identical to the liver-derived clone, and even with polymerase chain reaction oligotyping we did not find the liver-derived clonotypic TCR transcript in the PBMC, indicating a preferential intrahepatic localization of these T cells. Functionally, the liver-derived T cells provided help for polyclonal immunoglobulin (Ig)A production by B cells in vitro that is 10-fold more effective than that provided by the PBMC-derived clones, whereas there is no difference in the help provided for IgM and IgG production. Altogether these results demonstrate that the protein NS4 is highly immunogenic for intrahepatic CD4+ T cells primed by HCV in vivo, and that there can be compartmentalization of some NS4-specific CD4+ T cells to the liver of patients with chronic hepatitis C.
authors.affiliation: Immunobiology Research Institute, Siena, Italy.
authors.forename: M A
authors.initials: MA
authors.lastname: Minutello
authors.forename: P
authors.initials: P
authors.lastname: Pileri
authors.forename: D
authors.initials: D
authors.lastname: Unutmaz
authors.forename: S
authors.initials: S
authors.lastname: Censini
authors.forename: G
authors.initials: G
authors.lastname: Kuo
authors.forename: M
authors.initials: M
authors.lastname: Houghton
authors.forename: M R
authors.initials: MR
authors.lastname: Brunetto
authors.forename: F
authors.initials: F
authors.lastname: Bonino
authors.forename: S
authors.initials: S
authors.lastname: Abrignani
mesh_terms: D000328:Adult; D001483:Base Sequence; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002460:Cell Line; D002908:Chronic Disease; D005260:Female; D016174:Hepacivirus / Q000276:immunology*; D006526:Hepatitis C / Q000276:immunology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008099:Liver / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D013601:T-Lymphocytes / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000276:immunology*
chemical_list: D017361:Viral Nonstructural Proteins