PRTN3 and rheumatoid arthritis: Previously, we have shown that a subset of RA synovial recombinant monoclonal antibodies (rmAbs) generated from single CD19+ synovial B cells isolated from synovial tissue of patients with ELS+ACPA+ RA are able to recognize stromal-derived autoantigens (18), prompting further investigation of other potentially stromal-derived autoantigens targeted by the B cells differentiated in the ELS+ synovium and their pathogenic potential in contributing to chronic inflammation.