Immunology

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Useful for:

• The differentiation of Dermatomyositis (DM) and Polymyositis (PM).
• Indicating an underlying tumour disease.

Clinical Information:

• Polymyositis (PM) is a systemic inflammatory disease associated with perivascular lymphocytic infiltration.
• In some patients the skin may also become involved in the disease process. This is termed Dermatomyositis (DM).
• Although Dermatomyositis (DM) and Polymyositis (PM) share many characteristics with autoimmune diseases, the disease is often caused by an underlying malignancy/paraneoplastic origin.
• Clinical symptoms of Dermatomyositis (DM) and Polymyositis (PM) include muscle weakness and unspecific inflammation.
• Along with clinical symptoms and histological findings, the autoantibodies detected in this assay can play an important role in the diagnosis and classification of the disease.
• Mi-2α antibodies: Found in approximately 20% of patients with Dermatomysitis (DM).
• Mi-2β antibodies: More commonly found in Dermatomysitis (DM) patients with an associated neoplasia.
• TIF-1γ antibodies: Found in approximately 15% of patients with Dermatomysitis (DM) exclusively. Approximately 58% of these positive patients have an associated malignancy.
• MDA5 antibodies: Found in approximately 13 - 26% of patients with Dermatomysitis (DM).
• NPX2 antibodies: Found in approximately 18 - 25% of patients with jeuvnile Dermatomysitis (DM) and or Polymyositis (PM), and in approximately 1% of adult cases. Also associated with calcinosis and a more chronic and severe disease course.
• SAE1 antibodies: Found in approximately 8% of patients with Dermatomysitis (DM) and have a high disease specificity. Also found in approximately 5% of patients with Dermatomysitis (DM) associated with Interstitial Lung Disease (IDL).
• Ku antibodies: Found in approximately 5 - 25% of patients with Polymyositis (PM)/Systemic Sclerosis overlap syndrome.
• PM-Scl75 antibodies: The main antibody responsible for the immune responce in diffuse Systemic Sclerosis.
• PM-Scl100 antibodies: The main antibody responsible for the immune responce in Polymyositis (PM)/Systemic Sclerosis overlap syndrome.
• Signal Recognition Particle (SNP) antibodies: Found in approximately 4 - 5% of patients with Dermatomysitis (DM) and or Polymyositis (PM).
• Jo-1, PL-7, PL-12, EJ and OJ antibodies: Found in approximately 25 - 55%, 3 - 6%, up to 3%, 1% and 1% repectively of patients with Dermatomysitis (DM) and or Polymyositis (PM).
• Ro-52 antibodies: Found in approximately 25% of patients with Dermatomysitis (DM) and or Polymyositis (PM).

Please Note:

• All samples for Myositis Antibody Screen will also have an Antinuclear Antibody (ANA) assay performed.
• Where External Institiutions cannot guarantee immediate delivery, samples must be centrifuged, separated and stored at 4^oC. Samples can then be transported, as soon as possible, to St. James's Hospital for processing.

Related links

Reference range

 Negative

 Weak Positive

 Positive

 Strong Positive

Last updated

Fri, 19 Jul 2024 09:36:56 IST