PRTN3 and rheumatoid arthritis: On that topic, ACPA-positive patients have different disease spectra if compared to ACPA-negative ones; interestingly, differences are also relevant at the histological level: biopsy studies consistently show that ACPA-positive RA is enriched in B cell and plasma cell infiltrates, higher CXCL13 and immunoglobulin gene expression, and lympho-myeloid pathotypes [35].