Compared to MRL/lpr mice, MRL/lpr-p21tg mice showed clear improvement in critical aspects of lupus-like kidney disease such as lower immune complex deposition, decreased inflammatory infiltration of CD4+ T cells and F4/80+ macrophages (Fig. 9B), and reduced glomerulonephritis (Fig. 9C). This evidence concerns the gene CD4 and systemic lupus erythematosus.