Anti-transglutaminase 2 antibodies (anti-TG2)

Highly specific marker for coeliac disease (an autoimmune condition). Is looked at in coeliac diagnostics.

What antibodies against transglutaminase 2 show

Transglutaminase 2 (TG2, tissue transglutaminase) is an enzyme of the body that, among other things, cross-links proteins in connective tissue. In the gut lining it can alter gliadin fragments from gluten: it converts individual glutamine building blocks into glutamic acid (deamidation). In people with the tissue types HLA-DQ2 or HLA-DQ8, these altered fragments fit particularly well into the presenting molecules of immune cells and activate gluten-specific T cells. These help B cells that recognise complexes of TG2 and gliadin – so antibodies against the body's own enzyme are formed, usually of the IgA class. Their formation depends on gluten consumption.

Anti-TG2 not detected – what does it mean?

At the time of sampling, the immune system had not formed any measurable antibodies against transglutaminase 2. Because the antibodies are only formed when gluten is eaten, they can fall below the detection limit after a period with little or no gluten. With an inborn IgA deficiency, IgA antibodies are also absent; IgG antibodies and total IgA are then looked at as well.

Anti-TG2 detected – what happens in the body?

A positive result shows an immune reaction against the body's own enzyme that is triggered by gluten. In coeliac disease, activated T cells migrate into the lining of the small intestine and release inflammatory messengers; the intestinal villi become flatter, and the surface for absorbing nutrients shrinks. Iron, folic acid, vitamin B12, calcium and vitamin D are then absorbed less well, which can lead to anaemia, diarrhoea, weight loss and, in children, growth disorders. Antibodies against TG2 occur mainly in coeliac disease, and in low amounts also in some other autoimmune diseases. Confirmation is carried out by a doctor, usually with a tissue sample from the small intestine.

The interpretation is given in your report.