Previous studies demonstrated that the concentrations of MIF in serum and local tissue were significantly elevated in asthma (Lan et al., 2020; Li et al., 2021), atopic dermatitis (Yoshihisa et al., 2011), rheumatoid arthritis (Bilsborrow et al., 2019), and systemic lupus erythematosus (Gamez-Nava et al., 2020). Here, MIF is linked to rheumatoid arthritis.