type III hypersensitivity reaction
In this type of hypersensitivity reaction IgG class or IgM class antibodies combine with antigen to form immune complexes. These complexes are usually removed by the reticuloendothelial system.
However, if they are deposited in tissues, they may cause a hypersensitivity reaction in which the immune complexes activate complement and cause a tissue damaging local reaction.
Immune complexes may be soluble, as with adverse transfusion reactions, or they may be insoluble, becoming deposited in tissues which subsequently suffer damage i.e. pulmonary aspergillosis & erythema nodosum.
Last reviewed 06/2021