Paul G Hellewell, Applied Pharmacology, Imperial College School of Medicine at the National Heart and Lung Institute, London, UK
Adriano G Rossi, Respiratory Medicine Unit, Department of Medicine, Rayne Laboratory, Edinburgh, UK
The Arthus reaction was first described by Maurice Arthus as an acute inflammatory response induced in rabbit skin by a local injection of horse serum in rabbits sensitized by previous injections of the same substance. Although the reaction described originally could have had components of anaphylactic and delayed hypersensitivity responses, the term Arthus reaction best describes the acute response initiated by local deposition of immune complexes and is an example of type III hypersensitivity. Strictly speaking, the Arthus reaction is restricted to the skin and Arthus-like or Arthus-type reactions occur in other organs.
Antibody-antigen complexes are believed to be principal in the inflammatory response associated with a number of diverse diseases which are listed in Table 1. Some of these are well known while others are more obscure and are complications of other dis-
Table 1 Diseases and conditions which have features of the Arthus reaction
Systemic lupus erythematosus
Erythema nodosum leprosum
Inflammatory demyelinating neuropathies
Drug hypersensitivity eases (e.g. erythema nodosum leprosum is a serious complication of lepromatous leprosy) or can be adverse reactions to drugs. In the Arthus reaction as originally described, antigen was injected intra-dermally into sensitized animals and, as antibody diffused from cutaneous microvessels, immune complexes were deposited in and around the vessel wall. Experimentally it is convenient to induce the reaction passively and in reverse, such that antibody is injected intradermally and antigen intravenously -the so-called reversed passive Arthus reaction.
The Arthus reaction can be dissected into three fairly distinct stages: a rapid increase in vascular permeability and extravasation of plasma protein, which is maximal at 1-2 hours, infiltration of leukocytes (initially neutrophils) and hemorrhage which peak in intensity after 4-8 hours. Longer reactions are sometimes associated with necrosis. Experimentally, hemorrhage is the most notable feature of the reaction in transparent tissues such as skin.
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