IL-17A and IL-17F Expression in B Lymphocytes

Background: Recent evidence suggests that cells other than Th-17 lymphocytes express interleukin (IL)-17A and IL-17F and contribute to the production of these cytokines in immunologically mediated diseases. B lymphocytes are known to be an important source of cytokines in chronic inflammatory diseases. We therefore investigated the potential of human B lymphocytes to produce IL-17A and IL-17F. Methods: Highly purified B cells were obtained using a multiple-step separation procedure which included rosette depletion, adherence depletion, CD3+ cell magnetic activated depletion and CD19+ magnetic activated positive cell selection. In these CD19+ B cell fractions, CD3+/CD4+ and CD14+ cells were negligible (<0.2%), and CD8 and CD161 mRNAs were undetectable. The CD19+/CD20+ B cells were stimulated with IL-4, interferon-gamma, IL-6, IL-23 and transforming growth factor (TGF)-beta, and the expression of IL-17A and IL-17F in response to stimulation was determined by quantitative reverse transcription (RT)-PCR, Western blot, immunocytochemistry and ELISA. Results: Evidence of expression of IL-17A and IL-17F in purified B cells was obtained using RT-PCR, flow cytometry, immunofluorescence microscopy, Western immunoblotting and ELISA. Stimulation of B cells with IL-6, IL-23 or TGF-beta upregulated the expression of both IL-17A and F cytokines. Conclusions: These novel findings provide evidence that cytokine-stimulated B lymphocytes could be a significant source of IL-17A and IL-17F and support the notion that these cells actively participate in immune responses via alternative mechanisms in addition to the classic release of antibodies. Copyright (C) 2011 S. Karger AG, Basel