To evaluate the immunogenicity of identified peptides, we assessed IFN-γ and IL-2 production by incubating peripheral blood mononuclear cells of HLA-DRB1∗01:01-positive RA patients (n = 6) and healthy donors (n = 4), and of HLA-DRB1∗04:01-positive RA patients (n = 5) and healthy donors (n = 4) with dual-selected synthetic peptides (Table S3 and Fig. S3, 4). Here, IL2 is linked to rheumatoid arthritis.