PRTN3 and rheumatoid arthritis: We stimulated ACPA+ RA PBMCs with 100 μM of individual citrullinated proteins including cit-vimentin, cit-fibrinogen, cit-α-enolase, cit-H2B, cit-H3 or cit-H4; or a mix of all 6 citrullinated proteins each at 20 μM; or a mix of all 6 native proteins each at 20 μM; and measured IFNγ and GzmB expression by CD8+ T cells by flow cytometry.