Arthus reaction

Ar·thus reaction 'är-thəs-, ȧr-'tues- n a reaction that follows injection of an antigen into an animal in which hypersensitivity has been previously established and that involves infiltrations, edema, sterile abscesses, and in severe cases gangrene called also Arthus phenomenon

Ar·thus ȧr-tues Nicolas Maurice (1862-1945)

French bacteriologist and physiologist. Arthus was primarily concerned with venoms and antivenins and with coagulability and anticoagulants. In 1890 he published an article on coagulation that demonstrated for the first time the essential role of calcium in blood coagulation. In 1903, in an article reporting a study involving repeated injections of horse serum into rabbits, he reported discovery of the phenomenon of local anaphylaxis, a phenomenon that has since become identified with his name.

* * *

the development of an inflammatory lesion, with induration, erythema, edema, hemorrhage, and necrosis, a few hours after intradermal injection of antigen into a previously sensitized animal producing precipitating antibody; it is classed as a type III hypersensitivity reaction in the Gell and Coombs classification of immune responses. The lesion results from the precipitation of antigen-antibody complexes, which causes complement activation and the release of complement fragments that are chemotactic for neutrophils; large numbers of neutrophils infiltrate the site and cause tissue destruction by release of lysosomal enzymes. Called also Arthus phenomenon.