Identification of Novel, Immunogenic HLA-DR-Presented Prevotella copri Peptides in Patients With Rheumatoid Arthritis.

The majority of the RA patients had Pc immune responses. The correlation of IgA Pc antibody responses, particularly to Pc-p27, with ACPA supports the hypothesis that specific microbial antigens in the mucosa have a role in shaping or amplifying immune responses in RA joints.