Rheumatology Advance Access published online on July 17, 2008
Rheumatology, doi:10.1093/rheumatology/ken263
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A role for the integrin
6β1 in the differential distribution of CD4 and CD8 T-cell subsets within the rheumatoid synovium
1Rheumatology Research Group, 2BHF Centre for Cardiovascular Sciences and 3Liver Research Laboratories, MRC Centre for Immune Regulation, Institute for Biomedical Research, University of Birmingham, Birmingham, UK.
Correspondence to:
C. D. Buckley, Division of Immunity and Infection, University of Birmingham, Birmingham, B15 2TT. E-mail: c.d.buckley{at}bham.ac.uk.
| Abstract |
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Objective. CD4 and CD8 T-cell subsets accumulate in distinct microdomains within the inflamed rheumatoid synovium. The molecular basis for their differential distribution remains unclear. Since chemokines and adhesion molecules play an important role in the positioning of leucocytes at sites of inflammation, we tested the hypothesis that the differential expression and function of chemokine and/or adhesion molecules explains why CD4+ T cells accumulate within perivascular cuffs, whereas CD8+ T cells distribute diffusely within the tissue.
Methods. Expression of an extensive panel of chemokine receptors and adhesion molecules on matched CD4+ and CD8+ T cells from peripheral blood (PB) and synovial fluid (SF) was analysed by multicolour flow cytometry. Migration assays and flow-based adhesion assays were used to assess the functional consequences of any differences in the expression of chemokine and adhesion receptors.
Results. CD4+ and CD8+ T cells from PB and SF expressed unique yet consistent patterns of chemokine and adhesion receptors. SF CD8+ T cells were much less promiscuous in their expression of chemokine receptors than SF CD4+ T cells. The
6β1 integrin was highly expressed on PB CD4+ T cells, but not on PB CD8+ T cells. Laminin, the ligand for
6β1, retained CD4+ T cells, but less so CD8+ T cells, within inflamed synovial tissue.
Conclusion. Infiltrating PB CD4+ T cells, but not CD8+ T cells, express functional levels of the
6β1 integrin. We propose that this leads to their retention within the rheumatoid synovium in perivascular cuffs, which are defined and delineated by the expression of laminin.
KEY WORDS: T cells, Alpha 6 integrin, Chemokine receptors, Rheumatoid arthritis
Submitted 31 December 2007;
revised version accepted 18 June 2008.
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