IFNB1 and rheumatoid arthritis: In the RA group, the frequency of pDC in blood samples strongly correlated with the stain intensity of IFN-β in ducts (p < 0.0001, r = 0.988) and stain intensity and stain outspread of NK cells (NKG2+) in LMSG (p < 0.0001, r = 0.988∗).