APCS and lupus nephritis: We have provided here evidence that relative insufficiency of SAP played a critical role in the pathological process of the ALD-DNA-induced lupus nephritis, and verified that administration of SAP in vivo by a plasmid encoding the SAP, could significantly ameliorated the severity of SLE disease, as demonstrated by decreased levels of anti-dsDNA antibodies, reduced immune complex deposition, less proteinuria, less lupus nephritis, and decreased kidney score of glomerulonephritis.