Serum sickness resulting from repeated administration of horse antitoxins was hypothesized to be an immune complex disease by von Pirquet and Schick at the turn of this century (1 ). Arthus developed the first animal model of immune complex disease by inducing cutaneous vasculitis and inflammation following injection of antigen in immunized rabbits (2 ). In the 1940s Heidel-berger observed that complement inhibited the formation of precipitating antigen-antibody lattices. In the 1950s and 1960s, experimental serum sickness models of glomerulonephritis and vasculitis demonstrated the potential for circulating immune complexes to cause disease (3 ,4 ).