The levels of RF_IgA, RF_IgG, and RF_IgM in RA combined with DM group were [40.55 (20.32, 83.94) IU/mL], [20.21 (8.64, 58.11) U/mL], and [11.40 (7.37, 120.64) IU/mL], respectively. Here, CD40LG is linked to rheumatoid arthritis.