Increased proportion of CD56^bright natural killer cells in active and inactive systemic lupus erythematosus

Authors: Schepis, Danika¹; Gunnarsson, Iva²; Eloranta, Maija-Leena³; Lampa, Jon²; Jacobson, Stefan H.⁴; Kärre, Klas¹; Berg, Louise¹

Source: Immunology, Volume 126, Number 1, January 2009 , pp. 140-146(7)

Publisher: Wiley-Blackwell

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Abstract:

Summary

Natural killer (NK) cells belong to the innate immune system but can also affect adaptive immune reactions. This immune regulatory function is often ascribed to the CD56^bright subpopulation of NK cells that is prevalent in secondary lymphoid tissues and has potent cytokine-producing ability. The NK cells have been described as affecting autoimmune disease and stimulating B-cell production of antibodies, but their role in systemic lupus erythematosus (SLE) pathology has not been extensively studied. We have studied NK cells in SLE, a B-cell-driven systemic autoimmune disease, and phenotypically characterized peripheral blood NK cells in comparison to NK cells from patients with immunoglobulin A nephritis, rheumatoid arthritis and healthy individuals. We have found an increased proportion of CD56^bright NK cells in SLE, regardless of disease activity. We detected a somewhat increased expression of the activating receptor NKp46/CD335 on NK cells from SLE patients, although neither the percentage of NK cells of all lymphocytes nor the expression of other NK receptors analysed (LIR-1/CD85j, CD94, NKG2C/CD159c, NKG2D/CD314, NKp30/CD337, NKp44/CD336, CD69) differed between patient groups. We show that type I interferon, a proinflammatory cytokine known to be abundant in SLE, can cause increases of CD56^bright NK cells in vitro. We confirmed that serum levels of interferon-α were increased in active, but not in inactive, disease in the SLE patient group. In conclusion, we found an increased proportion of CD56^bright NK cells in the blood of SLE patients, although it remains to be examined whether and how this relates to the disease process.

Keywords: CD56bright natural killer cell; natural killer cells; systemic lupus erythematosus; type I interferon

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1365-2567.2008.02887.x

Affiliations: 1: Department of Microbiology, Tumour and Cell Biology, Strategic Research Center IRIS, Karolinska Institutet, Stockholm 2: Department of Medicine, Unit of Rheumatology, Karolinska Institutet, Stockholm 3: Department of Medical Sciences, Systemic Autoimmunity Group, Uppsala University, Uppsala 4: Department of Nephrology, Danderyd University Hospital, Stockholm, Sweden

Publication date: 2009-01-01