HLA-DRB1 and rheumatoid arthritis: CD74 is a membrane protein mainly distributed on the surface of immune cells, which transduces signals by binding to MIF (Sánchez-Zuno et al., 2021), while HLA-DRB1 sharesepitope sequences that mainly encode antigen presentation proteins and contribute to ACPA-positive RA (Kampstra and Toes, 2017).