The cell division indexes in SLE T cells stimulated with anti-CD3/CD28 plus control IgG and with anti-CD3/CD28 plus anti-CD200R1 antibody at 20 ng/ml or 100 ng/ml were 0.87 ± 0.54, 1.43 ± 0.92, and 2.34 ± 1.85, respectively (P < 0.05). Here, CD28 is linked to systemic lupus erythematosus.