Objective: To analyse the distribution of FOXP3+CD25+CD4+ regulatory T cells (Treg) in peripheral blood, synovial fluid and tissue of patients with rheumatic disease during relapse and after local treatment.
Methods: FOXP3 expression was assessed by flow cytometry, immunohistochemistry, immunofluorescence and real-time polymerase chain reaction (RT-PCR). The functional suppressive capacity of Treg was analysed after co-culture with effector CD4+CD25− T cells through assessment of proliferation and cytokine secretion.
Results: It was shown that FOXP3 protein and mRNA expression in synovial fluid T cells was not confined solely to CD25bright T cells as seen in blood, but included CD25intermediate and even CD25neg T cells. Indeed, synovial fluid CD25high T cells showed similar suppressive capacity as CD25bright T cells, indicating the presence of functional Treg in T cells with lower intensity of CD25. In synovial tissue, FOXP3+ cells were present in low numbers within T-cell infiltrates and decreased further after intra-articular glucocorticosteroid administration, in parallel with the general reduction in inflammation.
Conclusions: Identification of synovial fluid FOXP3+ Treg with varying intensities of CD25 opens up possibilities for thorough characterisation of this important T-cell subset in the inflammatory compartment. However, only scarce synovial membrane expression of FOXP3 was found even in the absence of overt inflammation, suggesting that the synovial membrane is a site that would benefit therapeutically from Treg expansion.
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▸ Additional figures are published online only at http://ard.bmj.com/content/vol68/issue12
TDC, MW, KR and JH contributed equally to the studies.
Funding This study was supported by grants from Margareta af Ugglas, Alex and Eva Wallström, Börje Dahlin, Tore Nilsson, Magn. Bergvall, Nanna Svartz’, Åke Wiberg, King Gustaf the V:s 80 year Foundation, Swedish Association against Rheumatism, Swedish Medical Association, Swedish Research Council, an EU FP6 project, AutoCure LSHB CT- 006-018661, 2 and Leukemia Research Fund (Alison Banham).
Competing interests AHB and GR receive royalty payments from the licensing of their anti-FOXP3 monoclonal antibodies. The remaining authors declare no competing interests.
Ethics approval Approval from the Karolinska University Hospital.
This publication reflects only the author’s views; the European Community is not liable for any use that may be made of the information herein.
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