It has been noted that patients with RA (both new-onset and chronic) either showed IgA-like antibody responses to Prevotella copri (P. copri) or its 27-kDa protein, which are associated with the production of TH17 cell cytokines and the presence of ACPAs [31].Additionally, intestinal tissue samples from patients with RA contain higher IgA antibodies that identify dietary antigens [32]. This evidence concerns the gene CD79A and rheumatoid arthritis.