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 (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-β 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.