Type III hypersensitivity is caused by circulating immunocomplexes (see Fig. 2-29C) and is typified by serum sickness (a drug reaction in which multimeric drug-antibody aggregates form in solution). Preformed immunocomplexes deposit in various vascular beds and cause injury at these sites.
0:157:54Type III hypersensitivity (immune complex mediated) - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd a growing collection of pharmacology. And clinical reasoning topics. Try it free today. Having aMoreAnd a growing collection of pharmacology. And clinical reasoning topics. Try it free today. Having a hypersensitivity means that someone's immune system has reacted to something in a way that ends up
Examples of type III hypersensitivity reactions include drug-induced serum sickness, farmer's lung and systemic lupus erythematosus.
What is the mechanism of type III hypersensitivity? Antibodies react to soluble antigen by forming lattices of antibody and antigen called an immune complex. When immune complexes (IgG or IgM) which are normally removed by macropahges in sleen or liver form in large amounts they overwhelm these coping strategies.
A good example of a type III Hypersensitivity is the autoimmune disease systemic lupus erythematosus, also just called lupus.
Poststreptococcal glomerulonephritis (PSGN) is characterized by rapid deterioration of kidney functions due to an inflammatory response (type III hypersensitivity reaction) following streptococcal infection.