Anti-LKM antibodies are autoantibodies that target liver and kidney cells. Our immune system defends our body against attacks from foreign cells and organisms. Often, our immune system goes haywire and mistakes some of its own tissues for foreign tissues. The production of antibodies against the body’s own tissues is the cause of a large number of autoimmune diseases such as rheumatoid arthritis, juvenile diabetes and several thyroid and livers diseases. When the immune system produces antibodies against microsomes (small intracellular structures) in the liver cells, autoimmune hepatitis can develop. Anti-LKM are generally tested for at the same time as anti-smooth muscle antibodies and antinuclear antibodies.
High anti-LKM levels indicate that the person is likely to have type 2 autoimmune hepatitis (sometimes combined with other autoimmune diseases such as type 1 diabetes or thyroiditis). However, a liver biopsy is required to confirm this diagnosis. If there are signs of liver disease combined with negative anti-LKM results but positive antinuclear and anti-smooth muscle antibody results, the individual is more likely to have type 1 autoimmune hepatitis. If the anti-LKM and anti-smooth muscle antibody tests are negative, autoimmune hepatitis is unlikely but cannot be completely ruled out.