Type III Autoimmune Reactions
(Immune Complex Disease)
Autoantibodies also cause disease by forming network of autoantibodies bound to their antigens (immune complexes). The antigen-antibody complexes can deposit in tissue, causing inflammatory lesions. Studies of serum sickness led to the first description of an immune complex disease. Serum sickeness is manifested by fever, glomerulonephritis, vasculitis, urticaria and arthritis, appearing seven to twenty-one days after primary immunization with a foreign protein. Two consequences of immune complex formation are complement fixation and binding to Fc or complement receptors on phagocytes. Clearance is facilitated by the binding of immune complexes to C3b receptors (CR1) on erythrocytes, which retain the complexes in the circulation until their removal by the reticuloendothelial cells of the spleen or liver.