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autoimmune hepatitis 87 autoimmune tubulointerstitial nephritis
autoimmune hepatitis
Approximately 10 to 20% of chronic hepatitis cases are
attributable to autoimmune hepatitis. The diagnosis of
autoimmune hepatitis is based on clinical and laboratory
criteria defined by the International Autoimmune Hepatitis
Group (IAHG). Circulating autoantibodies are hallmarks
of this syndrome. Whereas immune defects occur during
the chronic course of viral hepatitis, loss of tolerance to
autologous liver tissue is the principal pathogenic mechanism
in autoimmune hepatitis. It is important to distinguish
between autoimmune and viral hepatitis because interferons
administered for viral hepatitis are contraindicated in
autoimmune liver disease. Immunosuppression prolongs
survival in autoimmune hepatitis but favors viral replication.
Drug-induced liver injury may also be immune
mediated.
autoimmune lymphoproliferative syndromes (ALPS)
A group of rare primary immunodeficiency disorders
in children characterized by lymphocytosis, hypergammaglobulinemia,
hepatosplenomegaly, prominent lymphadenopathy,
antinuclear and anti-red blood cell antibodies
and accumulation of CD4 – CD8 – T cells. It is believed to
be associated with a defect in the Fas–Fas L apoptosis
signaling system. Some children with the disorder have
autoimmune hemolytic anemia, neutropenia, and thrombocytopenia.
ALPS is associated with inherited genes that
encode defective versions of the Fas protein. Fas alleles
in children with ALPS have been shown to be heterozygous
and manifest interference with T cell apoptosis. Fas
mutations in these children include single- or multiplebased
lesions, substitutions, or duplications leading to
premature termination of transcription or aberrant Fas
mRNA splicing. These alterations produce truncated or
elongated forms of Fas and are not detected in normal
persons. Murine lpr and gld disease models are being used
to investigate how Fas molecule mutations may interfere at
the molecular level with cell death signaling and contribute
to human lymphoproliferative and autoimmune disorders.
Like lpr and gld mice, children develop double negative
T cells and hypergammaglobulinemia. Unlike the mouse
mutations, affected patients rarely develop antinuclear
antibodies or lupus-like renal pathology. There may be
increased susceptibility, based on long-term observations
of a few patients.
autoimmune myocarditis
Inflammation associated with an autoimmune response
to myocardial tissues of the heart. Cardiac myosin has
been postulated to be the target autoantigen. May result in
chronic heart disease or dilated cardiomyopathy.
autoimmune neutropenia
This can be an isolated condition or appear secondary to
autoimmune disease. Patients may exhibit recurrent infections
or remain asymptomatic. Antigranulocyte antibodies
may be demonstrated. Bone marrow function is normal,
with myeloid hyperplasia and a shift to the left as a result of
increased granulocyte destruction. The autoantibody may
suppress myeloid cell growth. The condition is treated by
immunosuppressive drugs, corticosteroids, or splenectomy.
Patients with systemic lupus erythematosus (SLE), Felty’s
syndrome (rheumatoid arthritis, splenomegaly, and severe
neutropenia), and other autoimmune diseases may manifest
autoimmune neutropenia.
autoimmune polyendocrinopathy–candidiasis–ectodermal
dystrophy (APECED)
An autoimmune disease associated with a mutation in
AIRE, a transcriptional co-activator requisite for thymic
epithelial cells to express peripheral self-antigens. A deficiency
in AIRE leads to a defect in central tolerance. The
disorder is marked by chronic mucosal yeast infection and
autoimmune assaults on several endocrine glands, including
thyroid, pancreas, and adrenal. Also called autoimmune
polyglandular disease (APD). Refer also to autoimmune
polyglandular syndrome (APS).
autoimmune polyglandular syndrome (APS)
A designation for Addison’s disease and associated diseases
based on classification into type I, II, and III APSs. Type
I APS patients have chronic mucocutaneous candidiasis,
adrenal insufficiency, and hypoparathyroidism and may
also have gonadal failure, alopecia, malabsorption, pernicious
anemia, and chronic active hepatitis. Candidiasis and
malabsorption may also be present. Type II APS consists
of three primary disorders: Addison’s disease, insulin-dependent
diabetes mellitus, and autoimmune thyroid disease.
Type III APS consists of a subgroup of type II without
Addison’s disease but with thyroid autoimmunity and pernicious
anemia, as well as vitiligo.
autoimmune response
An antibody or T cell immune response to self antigens.
autoimmune skin diseases
Autoimmune diseases of the skin include pemphigus, pemphigoid,
epidermolysis bullosa acquisita, linear bullous IgA
disease, herpes gestationes, and cutaneous lupus erythematosus.
Probable autoimmune skin diseases may also include
psoriasis, lichen ruber planus, alopecia areata, actinic
reticuloid, morphea, and scleroderma. Possible autoimmune
diseases include pyoderma gangrenosum, parapsoriasis, and
sarcoidosis.
autoimmune thrombocytopenia
Decreased blood platelets attributable to interaction with
platelet-specific autoantibodies that mediate thrombocyte
destruction through phagocytosis. This may be an acute or
chronic condition that has a type II hypersensitivity mechanism.
May be manifested in immune thrombocytopenic
purpura (ITP) and thrombotic thrombocytopenic purpura
(TTP).
autoimmune thrombocytopenic purpura
A disease in which patients synthesize antibodies specific
for their own blood platelets. The antibody–platelet
reactants become bound to cells bearing Fc receptors and
complement receptors, leading to decreased blood platelets
followed by purpura or bleeding.
autoimmune thyroiditis
Refer to thyroiditis, autoimmune.
autoimmune tubulointerstitial nephritis
A renal disease believed to be mediated by anti-tubular basement
membrane (TBM) antibody. It is characterized by linear
deposition of immunoglobulin G (IgG) and occasionally
complement along tubular basement membranes. Occurs with
serum anti-TBM antibodies in 10 to 20% of cases. Symptoms
include tubular dysfunction with polyuria, proteinuria,
aminoaciduria, and glucosuria. TBM antigens that have been
identified include a 58-kDa TIN-antigen. Other nephritogenic
tubular interstitial antigens have also been identified in both
animal models of the disease and in humans.
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