Special Precautions/Comments:

Method: Indirect Immunofluorescence (IIF). Calibration: Referenced to published or in-house pattern images. EQA Scheme: UK NEQAS Scheme for General Autoimmune serology. IQC: Commercial preparation

Interferences: None known

Interpretation: Results are reported as Negative or Positive followed by a titre for each of the patterns (ie SMA, LKM or AMA). If AMAs are present, an M2 specific test will be requested. If a significant ANA is observed an ANA (Hep2) will be added. If a GPC antibody is observed then a GPC test is added but reported immediately. A GPC result cannot be interpreted in the prescence of a mitochondrial antibody. Test results are an aid to diagnosis and should not be considered as being diagnostic in themselves. Hence the test results should be used in conjunction with the patient’s clinical symptoms, the patient’s clinical history and any other available data, to produce an overall clinical diagnosis.

 

Additional Information:

Indication: Primary biliary cirrhosis (PBC). AMA – PBC. SMA/LKM – Autoimmune chronic active hepatitis (AICAH).

Background Information: The autoimmune liver screen utilises a composite tissue block of rat liver, kidney and stomach to detect anti-smooth muscle antibodies, anti- mitochondrial antibodies and liver kidney microsomal antibodies all of which can be used to assess for autoimmmune liver disease. Smooth Muscle Antibodies (SMA) can be found in the normal adult population, but high titres occur in patients with viral infection (such as hepatitis B and adenovirus) and autoimmune chronic active hepatitis. Low titres are common and not strongly associated with autoimmunity. Liver-Kidney Microsome (LKM), antibodies which stain cytoplasm of hepatocytes and proximal renal tubules, are rare, specific and found in a subgroup of ANA negative patients with autoimmune chronic active hepatitis (AICAH) – mainly type 2 AICAH. Three types of LKM have been described, LKM-1, LKM-2, LKM-3. LKM-1 can be determined by IIF; however LKM-2 and LKM-3 show similar staining patterns. Type 1 AICAH is characterised by SMA and ANA. Anti-Mitochondrial Antibodies (AMA) of M2 type are strongly associated with PBC although they can also be seen in other conditions such as rheumatoid arthritis, scleroderma, Sjögren’s syndrome and rare cases of AICAH. Different types of AMA are described, based on antigen specificity, designated on a numeric basis: M1 to M9. The AMA associated with PBC is usually M2a or M2b. Not all can be typed by IIF. An M2 specific Immunoassay is used to confirm a positive AMA by IIF

References: None

Telephone Gateshead Lab: 0191.4456499 Option 4, Option 1