ACAN and rheumatoid arthritis: Using DRB1*01:01 and DRB1*04:01 humanized mouse models, we assessed the relationship between HLA-DR binding affinity and T cell immunogenicity of WT and Cit forms of vimentin, aggrecan, type II collagen, and fibrinogen peptides and proteins associated with the autoimmune T cell response in RA [20, 21, 35, 36, 38].