Auto-antibodies to smooth muscle and mitochondria, LKM-1, SLA/LP, M2
In work-up of chronic inflammatory liver disease, particularly chronic active (lupoid) hepatitis and primary biliary cirrhosis.
Antibodies to smooth muscle (in vessels, gastrointestinal wall, and glomeruli) and mitochondria (in renal tubules and parietal cells) can be demonstrated by indirect immunofluorescence. Rat kidney/rat stomach is used as the antigen substrate.
Antibodies to LKM-1 (liver kidney microsomal antigen type 1) are demonstrated by immunoblotting, and positive reactions are confirmed with IIF (using rat kidney/rat stomach/rat liver as the antigen substrate). Anti-SLA/LP (soluble liver antigen/liver pancreas antigen) and anti-M2 (mitochondrial fraction 2) are demonstrated by immunoblotting.
Serum. Recommended blood quantity is ≥ 3 mL.
Sampling tube: Vacuum tube pl 4 mL with gel, red/yellow stopper.
Analysis order, Microbiology and immunology, USÖ.
Analysis usually carried out once a week.
IgG antibodies to smooth muscle (specificity for F-actin) in a titer (dilution factor) of 100 or more occur in about 70% of cases of chronic active hepatitis. Low levels of antibodies to smooth muscle (titer/dilution factor 25) sometimes occur in patients with other inflammation and with rising age.
20% of patients with autoimmune hepatitis have anti-SLA/LP antibodies. Of these, about half are negative for antibodies to both smooth muscle and ANA, or demonstrate only a weak reaction. The finding of anti-SLA/LP is specific to autoimmune hepatitis. An unusual variant in the antibody profile of autoimmune hepatitis demonstrates anti-LKM-1 antibodies exclusively. Anti-LKM-1 antibodies are relatively more common in children.
Mitochondrial antibodies can be demonstrated in most patients (> 95%) with primary biliary cirrhosis. Anti-mitochondrial antibodies specific to M2 are specifically found in primary biliary cirrhosis, while other mitochondrial reactivity can be seen in other inflammatory conditions.
Johnson GD, Holborow EJ, Glynn LE. Antibody to smooth muscle in patients with liver disease. Lancet 2:878-9, 1965.
Svensson Anne. Bestämning av normalvärden för antikroppsnivåer uppmätta med indirekt immunfluorescensteknik. C-uppsats 10p vid Institutionen för klinisk medicin, Programmet för biomedicinsk laboratorievetenskap 120 p, vårterminen 2006. [Determination of normal values for antibody levels measured with indirect immunofluorescence. Bachelor thesis (10 credits) at the Department of Clinical Medicine, Program for biomedical laboratory science (120 credits), spring term 2006]