In SLE patients, the proportion of CD4+Foxp3+ T cells was positively correlated with anti-dsDNA antibody titer (r = 0.57, P < 0.01) and SLEDAI (r = 0.52, P < 0.01) and negatively correlated with CH50 levels (r = 0.52, P < 0.01). Here, CD4 is linked to systemic lupus erythematosus.