RA SF contained more CD61+ [51], CD45+ [29], CD3+ [39], CD4+ [29, 40], CD4+/CD161+/CD39+ [40], CD4+/CD73+/CD39+ [40], CD8+ [29, 39], CD14+ [29], and CD66+ [29] EVs than OA SF, whereas there was no difference for CD20+ EVs [29]. Here, KLRB1 is linked to rheumatoid arthritis.