In addition, a study found that IL-21, IFN-γ, and IL-10 levels were the likely risk factors that affected ABCs in RA patients.[29] Thus, ABCs are associated with the pathogenesis of RA so that when ABCs increase due to internal factors or external circumstances in RA, like latent γ-herpesvirus infection, ABCs could exacerbate arthritis. Here, IL21 is linked to rheumatoid arthritis.