What are mitochondrial antibodies?
Mitochondrial antibodies (AMA or anti-mitochondrial antibody) are the antibodies directed against an antigen of the inner mitochondrial membrane. In-between 95 to 98 percent of patients with primary biliary cirrhosis (PBC) have auto antibodies in their blood that react with the inner lining of mitochondria. These auto antibodies are called anti-mitochondrial antibodies (AMA). Mitochondria is the energy that are present inside all of our cells, not just the cells of bile duct and liver. Mitochondria uses the oxygen that is carried in the blood from the lungs as a fuel to generate energy. Mitochondrial antibodies bind to protein antigens that are contained in multienzyme complexes, or packages of enzymes, that are within the inner lining of the mitochondria. The key chemical reactions necessary for life are these very important multienzyme complexes. They are known as the multienzyme complex as they are made up of multiple enzyme units.
These mitochondrial antibodies specifically react against a component of multienzyme complex known as E2. In patients that have primary biliary cirrhosis (PBC), these mitochondrial antibodies preferentially react with the E2 component of one of the multienzymes that is known as the pyruvate dehydrogenase complex (PDC).
Why measure the level of mitochondrial antibodies?
The presence of mitochondrial antibodies in the blood or serum of a human, may be indicative of the presence of and/or the potential to develop an autoimmune disease known as primary biliary cirrhosis (PBC). PBC normally causes scarring of liver tissues in the body, and is usually confined to the bile duct drainage system. There are many antigens that are associated with mitochondrial antibodies, which have been identified and are as follows; M1 – cardiolipin, M2 – branched chain alpha keto acid dehydrogenase complex, M3 – outer mitochondrial membrane, M4 – sulfite oxidase, M5 – outer mitochondrial membrane, M6 – outer mitochondrial membrane, M7 – sarcosine dehydrogenase, M8 – outer mitochondrial membrane, M9 – glycogen phosphorylase.
Antibodies to these specific antigens have been associated with a number of conditions, antigens M2, M4, M8 and M9 are associated with the primary biliary cirrhosis, while M2 is associated with autoimmune hepatitis, M3 is linked to drug induced lupus erythematous, M1 with autoimmune hepatitis, M6 with drug induced hepatitis, M7 with cardiomyopathy and myocarditis, M5 with systemic lupus erythematous, undifferentiated collagenosis and autoimmune haemolytic anemia. It is to be noted that these associations are not completely specific and should not be relied upon solely for a diagnosis.
Primary biliary cirrhosis are primarily present and seen in middle-aged women, and in those patients who are afflicted with other autoimmune diseases. In acute liver failure, mitochondrial antibodies are found against all major liver antigens, such as; Pyruvate dehydrogenase, E2 subunits, branched-chained 2-oxo-acid dehydrogenase, and 2-oxo-glutarate dehydrogenase.
Standard of preparation
Sampling is usually done in the morning, during your visit to the hospital. The doctor will recommend if you need to be fasting prior to the examination. Make sure to inform your doctor of any medication that you are currently taking, which may affect the results of the exam.
Is the exam painful or dangerous?
The examination is neither painful nor dangerous. The patient may feel a slight tingling sensation when the needle enters the arm, for the extraction of blood.
How is the exam performed?
The examination is done with a simple blood test.