Open Access Open Badges Research article

Expression of K2P5.1 potassium channels on CD4+ T lymphocytes correlates with disease activity in rheumatoid arthritis patients

Stefan Bittner1, Nicole Bobak2, Martin Feuchtenberger3, Alexander M Herrmann2, Kerstin Göbel2, Raimund W Kinne4, Anker J Hansen5, Thomas Budde6, Christoph Kleinschnitz1, Oliver Frey7, Hans-Peter Tony3, Heinz Wiendl2 and Sven G Meuth126*

Author Affiliations

1 Department of Neurology, University of Wuerzburg, Josef-Schneider-Str. 11, Wuerzburg, 97080, Germany

2 Department of Neurology - Inflammatory disorders of the nervous system and neurooncology, University of Muenster, Domagkstr. 13, Muenster, 48149, Germany

3 Department of Medicine II - Rheumatology and Clinical Immunology, Josef-Schneider-Str. 2, University of Wuerzburg, Wuerzburg, 97080, Germany

4 Department of Orthopedics - Experimental Rheumatology Unit, Friedrich Schiller University Jena, Klosterlausnitzer Str. 81, Eisenberg, 07607, Germany

5 Biopharmaceuticals Research, Novo Nordisk A/S, Novo Nordisk Park, Malov, 2760 Denmark

6 Institute of Physiology I, University of Muenster, Robert-Koch-Str. 27a, Muenster, 48149, Germany

7 Institute of Immunology, University Hospital Jena, Leutragraben 3, Jena, 07743, Germany

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Arthritis Research & Therapy 2011, 13:R21  doi:10.1186/ar3245

Published: 11 February 2011



CD4+ T cells express K2P5.1 (TWIK-related acid-sensitive potassium channel 2 (TASK2); KCNK5), a member of the two-pore domain potassium channel family, which has been shown to influence T cell effector functions. Recently, it was shown that K2P5.1 is upregulated upon (autoimmune) T cell stimulation. The aim of this study was to correlate expression levels of K2P5.1 on T cells from patients with rheumatoid arthritis (RA) to disease activity in these patients.


Expression levels of K2P5.1 were measured by RT-PCR in the peripheral blood of 58 patients with RA and correlated with disease activity parameters (C-reactive protein levels, erythrocyte sedimentation rates, disease activity score (DAS28) scores). Twenty patients undergoing therapy change were followed-up for six months. Additionally, synovial fluid and synovial biopsies were investigated for T lymphocytes expressing K2P5.1.


K2P5.1 expression levels in CD4+ T cells show a strong correlation to DAS28 scores in RA patients. Similar correlations were found for serological inflammatory parameters (erythrocyte sedimentation rate, C-reactive protein). In addition, K2P5.1 expression levels of synovial fluid-derived T cells are higher compared to peripheral blood T cells. Prospective data in individual patients show a parallel behaviour of K2P5.1 expression to disease activity parameters during a longitudinal follow-up for six months.


Disease activity in RA patients correlates strongly with K2P5.1 expression levels in CD4+ T lymphocytes in the peripheral blood in cross-sectional as well as in longitudinal observations. Further studies are needed to investigate the exact pathophysiological mechanisms and to evaluate the possible use of K2P5.1 as a potential biomarker for disease activity and differential diagnosis.