HLA-DRB1 and systemic lupus erythematosus: On the other hand, HLA-DRB1 molecules carry three risk residues (positions 11, 13, and 26) located in the peptide-binding groove for disease susceptibility of specific autoantibodies against autoantigens associated with SLE, which affect the interaction between amino acids of autoantigens and amino acids conforming to peptide-binding groove in HLA molecule and antigen presentation for T cell activation [47, 48].