Systemic lupus erythematosus (SLE) is a chronic autoimmune disease accompanied by the activation and proliferation of T cells and B cells.In this study,we found that the distributions of lymphocytes obtained from patients with SLE or SLE with renal disease (RSLE) were reduced in the G(0)/G(1) phase and were elevated in the S phase after phytohemagglutinin treatment.Increased expression of CDK2 and decreased expression of cyclin-dependent kinase inhibitors p27(Kip 1) and p21 (WAF1/CIP1) were observed in RSLE and SLE lymphocytes.