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autoimmune complement fixation reaction 86 autoimmune hemophilia
both rheumatic fever and Chagas’ disease in which T cells
are specifically cytotoxic for the target organ. Cytotoxic T
cells specific for cardiac myofibers appear in both rheumatic
fever and Chagas’ disease. Only selected individuals with
cardiomyopathy develop progressive autoimmune disease
after active infection.
autoimmune complement fixation reaction
The ability of sera from patients with certain autoimmune
diseases such as systemic lupus erythematosus, chronic
active hepatitis, etc., to fix complement when combined with
kidney, liver, or other tissue suspensions in saline.
autoimmune disease
Pathogenic consequences, including tissue injury, produced
by autoantibodies or autoreactive T lymphocytes interacting
with self epitopes (i.e., autoantigens). The mere presence of
autoantibodies or autoreactive T lymphocytes does not prove
a cause-and-effect relationship between these components
and a patient’s disease. To show that autoimmune phenomena
are involved in the etiology and pathogenesis of human
disease, Witebsky suggested that certain criteria be fulfilled
(see Witebsky’s criteria). In addition to autoimmune reactivity
against self constituents, tissue injury in the presence of
immunocompetent cells corresponding to the tissue distribution
of the autoantigen, duplication of the disease features in
experimental animals injected with the appropriate autoantigen,
and passive transfer with either autoantibody or autoreactive
T lymphocytes to normal animals offer evidence in
support of autoimmune pathogenesis. Individual autoimmune
diseases are discussed under their own headings, such as
systemic lupus erythematosus (SLE), autoimmune thyroiditis,
etc. Autoimmune diseases may be either organ-specific
(thyroiditis, diabetes) or systemic (SLE).
autoimmune disease animal models
Studies of human autoimmune disease have always been
confronted with the question of whether immune phenomena,
including the production of autoantibodies, represent
a cause or a consequence of the disease. The use of animal
models (rats, mice, guinea pigs, rabbits, monkeys, chickens,
and dogs, among other species) has helped answer many
of these questions. A broad spectrum of human autoimmune
diseases has been clarified through the use of animal
models that differ in detail but nevertheless provided insight
into pathogenic mechanisms, converging pathways, and
disturbances of normal regulatory function related to the
development of autoimmunity.
autoimmune disease spontaneous animal models
Animal strains based on years of selective breeding develop
certain organ-specific or systemic autoimmune diseases
spontaneously without experimental manipulation. These
models resemble the human condition to a remarkable
degree in many cases and serve as valuable models to investigate
pathogenetic mechanisms underlying disease development.
Spontaneous animal models for organ-specific
autoimmune diseases include the obese strains of chickens
that serve as animal models for Hashimoto’s thyroiditis.
Animal strains with spontaneous insulin-dependent diabetes
mellitus (IDDM) include NOD mice and DP-BB rats,
both of which develop humoral and cellular autoimmune
responses against islet β cells of the pancreas. Spontaneous
animal models of systemic autoimmune diseases include
the University of California at Davis (UCD) 200 strain
as an animal model for progressive systemic sclerosis
(SSc)–scleroderma. Several mouse strains develop systemic
lupus erythematosus-like autoimmunity. These include the
New Zealand black (NZB), (NZB × New Zealand White
[NZW])F1, (NZB × SWR)F1, BXSB, and MRL mice.
These animal models have contributed greatly to knowledge
of the etiopathogenesis, genetics, and molecular defects
responsible for autoimmunity. Mechanisms include defects
in lymphoid lineage, endocrine alterations, target organ
defects, endogenous viruses, and/or mutations in immunologically
relevant molecules such as major histocompatibility
complex (MHC) and cell receptor genes. Many of these
have been implicated in animal autoimmune diseases and in
some cases of human disease.
autoimmune gastritis
An organ-specific autoimmune disease in which
autoantibodies are formed against gastric antigens and
mononuclear cells infiltrate through target organs with
destruction. The disease is associated with a regenerative
response of the affected tissue to corticosteroid and
immunosuppressive drugs, familial predisposition, and
other autoimmune diseases. The molecular target of
parietal cell autoantibodies is the gastric H + /K + ATPase
located on secretory membranes of gastric parietal cells.
Refer also to pernicious anemia.
autoimmune hemolytic anemia
Although both warm antibody and cold antibody types
are known, the warm type is the most common and is
characterized by a positive direct antiglobulin (Coombs’
test) associated with lymphoreticular cancer or autoimmune
disease and splenomegaly. Patients may have
anemia, hemolysis, lymphadenopathy, hepatosplenomegaly,
or features of autoimmune disease. They commonly
exhibit normochromic, normocytic anemia with spherocytosis
and nucleated red blood cells in the peripheral
blood. Leukocytosis and thrombocytosis may also occur,
along with a significant reticulocytosis and an elevated
serum indirect (unconjugated) bilirubin. Immunoglobulin
G (IgG) and complement adhere to red blood cells.
Antibodies are directed principally against Rh antigens.
The indirect antiglobulin test is positive in 50% of cases,
and agglutination of enzyme-treated red blood cells is
positive in 90% of cases. In the cold agglutinin syndrome,
IgM antibodies with an anti-I specificity are involved.
Warm autoantibody autoimmune hemolytic anemia has a
fairly good prognosis.
autoimmune hemophilia
An acquired disorder that resembles the inborn disease of
coagulation due to a deficiency or dysfunction of Factor
VIII. Patients develop an autoantibody that can inactivate
Factor VIII. This auto-anti-Factor VIII antibody leads to an
acquired hemophilia that resembles inherited hemophilia.
This is a rare disorder that presents with spontaneous bleeding
that can be life threatening. It may occur spontaneously
or may be associated with other autoimmune disorders.
It may result from the treatment of inherited hemophilia
with preparations of Factor VIII. Soft tissues and muscles,
the gut, the postpartum uterus, and retroperitoneum all
represent sites of hemorrhage. Bleeding may also occur
following surgery. The acquired antibody to Factor VIII
is usually immunoglobulin G (IgG), of the IgG 4 subclass.
Anti-idiotypic antibodies may also be formed against anti-
Factor VIII antibodies.