CXCL13 and inflammation: This establishes circulating Tph cells as peripheral biomarkers for lymphomyeloid synovitis, a finding particularly relevant given the scarcity of peripheral biomarkers associated with this subtype of synovial inflammation because the only other circulating biomarker ever found in association with lymphomyeloid synovial inflammation and ELS formation is CXCL13,42 a chemokine produced mainly by Tph cells and their CXCR5+ counterpart.