When the fold increase in IL-17+ T cells after ex vivo stimulation for three days was compared between patients and controls, SLE patients exhibited significantly higher increases in CD4+ IL-17+ and CD8+ IL-17+ T cells, suggesting that PBMCs from SLE patients promoted the expansion of IL-17-producing T cells upon stimulation more vigorously than control PBMCs. The gene discussed is CD4; the disease is systemic lupus erythematosus.