Anti-SM antibody

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

Anti-nuclear antibodies (ANAs, also known as anti-nuclear factor or ANF) are autoantibodies directed against contents of the cell nucleus.[1]

They are present in higher than normal numbers in autoimmune disease. The ANA test measures the pattern and amount of autoantibody which can attack the body's tissues as if they were foreign material. Autoantibodies are present in low titers in the general population, but in about 5% of the pie, their concentration is increased, and about half of this 5% have an autoimmune disease.[citation needed]

ANA test

One can check for the presence of ANAs in blood serum by means of a laboratory test. There are also additional tests that allow one to test for individual ANAs. The general ANA test is usually one of two types: indirect immunofluorescence or ELISA.

Associated diseases

The normal titer of ANA is 1:40 or less. Higher titers are indicative of an autoimmune disease. The presence of ANA is indicative of lupus erythematosus (present in 80-90% of cases), though they also appear in some other auto-immune diseases such as[citation needed] Sjögren's syndrome (60%), rheumatoid arthritis (30-40%), autoimmune hepatitis, scleroderma and polymyositis & dermatomyositis (30%), and various non-rheumatological conditions associated with tissue damage. Other conditions with high ANA titre include[citation needed] Addison disease, Idiopathic thrombocytopenic purpura (ITP), Hashimoto's, Autoimmune hemolytic anemia, Type I diabetes mellitus, Mixed connective tissue disorder (MCTD).

Sensitivity

The following table list the prevalence of different types of ANAs for different diseases, in this case what percentage of those with the disease have the ANA. Some ANAs appear in several types of disease, resulting in lower specificity of the test.

ANA type Target antigen Sensitivity
SLE Drug-induced LE Diffuse systemic sclerosis Limited systemic scleroderma Sjögren syndrome Inflammatory myopathy MCTD
All ANAs
(by indirect IF)
Various >95 >95 70-90 70-90 50-80 40-60 95[2]
Anti-dsDNA DNA 40-60 - - - - - -[2]
Anti-Sm Core proteins of snRNPs 20-30 - - - - - -[2]
Anti-histone Histones 50-70 90[2] - 95 - - - - -[2]
Anti Scl-70 Type I topoisomerase - - 28-70 10-18 - - -[2]
Anti-centromere Centromeric proteins - - 22-26 90 - - -[2]
Anti-snRNP70 snRNP70 30[3]-40[3][2] -[2] 15[2] 10[2] -[2] 15[2] 90[2]
SS-A (Ro) RNPs 30-50 - - - 70-95 10 -[2]
SS-B (La) RNPs 10-15 - - - 60-90 - -[2]
Jo-1 Histidine-tRNA ligase - - - - - 25 -[2]
- = less than 5% sensitivity

Unless else specified in boxes, then ref is:[3]

ANA classification

Following detection of a high titer of ANAs (e.g. 1:160), various subtypes are determined.[4] This is typically done on cells of the HEp-2 cell line. Examples include

History

The LE cell was discovered in bone marrow in 1948 by Hargraves et al.[5] This was the first indication that processes affecting the cell nucleus were responsible for lupus erythematosus (LE).[citation needed] In the 1950s, progressively more sensitive and specific ANA serology tests became available.

See also

References

  1. Antinuclear+Antibody at the US National Library of Medicine Medical Subject Headings (MeSH)
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Table 6-2 in: Elizabeth D Agabegi; Agabegi, Steven S. (2008). Step-Up to Medicine (Step-Up Series). Hagerstwon, MD: Lippincott Williams & Wilkins. ISBN 0-7817-7153-6.
  3. 3.0 3.1 3.2 Table 5-9 in: Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson (2007). Robbins Basic Pathology. Philadelphia: Saunders. ISBN 1-4160-2973-7. 8th edition.
  4. Kavanaugh A, Tomar R, Reveille J, Solomon DH, Homburger HA. Guidelines for clinical use of the antinuclear antibody test and tests for specific autoantibodies to nuclear antigens. American College of Pathologists. Arch Pathol Lab Med 2000;124:71-81. PMID 10629135.
  5. Hargraves M, Richmond H, Morton R. Presentation of two bone marrow components, the tart cell and the LE cell. Mayo Clin Proc 1948;27:25–28.

External links

de:Antinukleärer Antikörper id:Antibodi anti-nuklear it:Anticorpi antinucleo nl:Antinucleaire antistof sv:Antinukleära antikroppar


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