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Arthus reaction 78 artificially acquired immunity
Maurice Arthus with students.
Arthus reaction
A reaction induced by repeated intradermal injections of
antigen into the same skin site. It is dependent upon the
development of humoral antibodies of the precipitin type
that react in vivo with specific antigen at a local site. The
reaction may also be induced by the inoculation of antigen
into a local skin site of an animal possessing preformed
immunoglobulin G (IgG) antibodies specific for the antigen.
Immune complexes are composed of antigen, antibody,
and complement formed in vessels. The chemotactic
complement fragment C5a and other chemotactic peptides
produced attract neutrophils to antigen–antibody–complement
complexes followed by lysosomal enzyme release,
which induces injury to vessel walls with the development
of thrombi, hemorrhage, edema, and necrosis. Events leading
to vascular necrosis include blood stasis, thrombosis,
capillary compression in vascular injury which causes
extravasation, venule rupture, hemorrhage, and local ischemia.
There is extensive infiltration of polymorphonuclear
RBC
Blood vessel
Vessel hemorrhage
Ag
Immune
complex
deposits
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cells, especially neutrophils, into the connective tissue.
Grossly, edema, erythema, central blanching, induration,
and petechiae appear. Petechiae develop within 2 hours,
reach a maximum between 4 and 6 hours, and then may
diminish or persist for 24 hours or longer with associated
central necrosis, depending on the severity of the reaction.
If the reaction is more prolonged, macrophages replace
neutrophils; histiocytes and plasma cells may also be
demonstrated. The Arthus reaction is considered a form of
immediate-type hypersensitivity, but it does not occur as
rapidly as does anaphylaxis. It takes place during a 4-hour
period and diminishes after 12 hours. Thereafter, the
area is cleared by mononuclear phagocytes. The passive
cutaneous Arthus reaction consists of the inoculation of
antibodies intravenously into a nonimmune host, followed
by local cutaneous injection of antigen. The reverse passive
cutaneous Arthus reaction requires the intracutaneous
injection of antibodies, followed by the intravenous
or incutaneous (at same site) administration of antigen.
The Arthus reaction is a form of type III hypersensitivity,
as it is based upon the formation of immune complexes
with complement fixation. Clinical situations for which it
serves as an animal model include serum sickness, glomerulonephritis,
and farmer’s lung.
artificial antigen
An antigen prepared by chemical modification of a natural
antigen. Compare with synthetic antigen.
artificial passive immunity
The transfer of immunoglobulins from an immune individual
to a nonimmune, susceptible recipient.
artificially acquired immunity
The use of deliberate active or passive immunization or
vaccination to elicit protective immunity as opposed to
immunity that results from unplanned and coincidental
exposure to antigenic materials including microorganisms
in the environment.
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Complement
PMN
Ab
PMN
Ag–Ab
complex
Complement
activation
Chemotaxis
Diapedesis
inflammation
Molecular, cellular, and tissue interactions in the Arthus reaction. RBC = red blood cell. PMN = polymorphonuclear neutrophil. Ag–Ab = antigen–antibody
complex.