90660:ANTIBODY TO LIVER/KIDNEY MICROSOME

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90660:ANTIBODY TO LIVER/KIDNEY MICROSOME
Alias Names: LKM IgG antibodies
Methodology: Indirect Fluorescent Antibody (IFA)
Edit Date: 6/11/2010
Performed: Monday, Thursday. Next run if titered.
Released: 1-5 days after setup at PeaceHealth Laboratories’ reference lab.
CPT Code: 86376-90
Specimen Collection Details
Collection: One 7.5 mL serum separator tube (SST).
Handling: Allow to clot, centrifuge and separate serum from cells and pour into a plastic vial. Freeze. Avoid repeated freeze/thaw cycles.
Stability: Specimen stable 24 hours ambient, 14 days refrigerated, or 1 year frozen.
Standard Volume: 1 mL serum.
Minimum Volume: 150 µL serum.
Transport: Frozen on dry ice.
Rejection Criteria: Severely hemolyzed or lipemic specimen; specimen frozen in glass tube.

Reference Range:
<1_20 Normal
Autoimmune hepatitis (AIH) is a chronic inflammatory liver disease, characterized by the presence of antibodies against microsomal antigens expressed within hepatocytes. AIH can be categorized into three separate disease groups based on the presence of marker autoantibodies in the serum of affected patients. AIH Type 1, the more common (60-70%), is characterized by the presence of autoantibodies against nuclear (ANA) and smooth muscle (ASM) antigens. AIH Type 2, which is less prevalent with only 10-20 cases per million, has an acute onset with a rapid progression to cirrhosis and liver failure. AIH Type 2 is characterized by the presence of specific antibodies (LKM-1) against LKM antigens (cytochrome P450IID6) and the absence of ANA and ASM. AIH Type 3 is characterized by the presence of autoantibodies against soluble liver antigens (SLA) which react with liver cytokeratins.

LKM-1 antibody reacts uniformly with cytochrome P450IID6, a 50 kDa protein found in the cytoplasm of all hepatocytes and renal proximal tubular cells. Studies in the early 1990s identified less than 3% of patients infected with hepatitis C virus have related antibodies that also recognize antigenic sites on P450IID6. LKM-2 antibody is associated with ticrynafen (tienilic acid) induced hepatitis. The target antigen for this antibody is cytochrome P450IIC9.

Although the specific LKM antigenic sites differ from one another, LKM-1 and LKM-2 antibodies cannot be differentiated using indirect fluorescent antibody (IFA) techniques.