CD4 and rheumatoid arthritis: Our study found that in patients with active RA, peripheral lymphocytes and CD4+ T cell subsets decreased to varying degrees, possibly due to lymphocyte depletion and the use of disease-modifying antirheumatic drugs. However, the numbers and percentages of NK cells increased significantly in the moderate-high disease activity group, and both were positively correlated with serum IL-2 levels.