Arthur's reaction
The Arthus reaction , which is also called the Arthus phenomenon , is a local type III hypersensitivity reaction or a reaction of the Arthus type (classic classification according to Coombs and Gell , see Allergy ).
The phenomenon is named after the physiologist Maurice Arthus , who discovered in 1903 that in previously sensitized test animals, after re-injection of the relevant antigen, severe inflammatory reactions occur near the injection site.
As a type III reaction, the Arthus reaction is based on an immune response against soluble antigens . Here are IgG - antibodies formed. If the antigen in question is injected subcutaneously again after the immune response or sensitization has taken place , the IgG antibodies formed can diffuse into the tissue and bind to the locally administered antigen. Because only a small amount of antigen is injected subcutaneously, there is only local formation of immune complexes . These immune complexes can bind to the FcγRIII receptors of mast cells or to leukocytes . A local inflammatory reaction is triggered, which manifests itself in an increased vascular permeability (wheal formation). The maximum of this reaction is reached after 3 to 8 hours, after 48 hours it has disappeared again.