CD40LG and rheumatoid arthritis: The results of our study showed that the positive rate of RF_IgA in RA patients was as high as 54.22%; the positive rate of RF_IgG was as high as 50.20%, and the positive rate of RF_IgM was as high as 59.44%; in healthy people, the positive rates of RF_IgA, RF_IgG, and RF_IgM were 12.08%, 8.05%, and 10.74%, respectively.