IL31 and rheumatoid arthritis: We observed that LPS significantly promoted the secretion of IL-25 and IL-31 but not IL-33 secretion from PBMC in both groups (Figure 1), whereas rhMIF only significantly increased the secretion of IL-25 [median 15.73, with interquartile range (IQR) 1.12–18.25 pg/mL, p < 0.01], IL-31 (median 57.12, IQR 47.43–76.16 pg/mL, p < 0.05), and IL-33 (median 6.13, IQR 2.07–7.11 pg/mL, p < 0.05) from PBMC of RA patients (Figure 1B,D,F).