ABCs display a complex cytokine profile distinct from other B cell subpopulations in RA, secreting proinflammatory cytokines like IL-21, IL-17A, TNF-α, and IFN-γ [103, 115], as well as regulatory cytokines such as IL-4 and IL-10 that suppress inflammation [116, 117]. This evidence concerns the gene IL17A and rheumatoid arthritis.