Studies underway continue earlier observations on immune complex biology using site-specifically cross-linked model complexes. Two major aspects are under study at the moment. First, the hepatic handling of model complexes in auto-immune mice is being studied in detail using organ perfusion. This approach allows a more detailed and subtle understanding than whole animal studies. Auto-immune mice show an abnormality in handling complexes before they are clinically ill. Second, in studies underway, the influence of drugs which are known to ameliorate auto-immune disease upon immune complex handling in normal and auto-immune mice, is being explored.