The blood dosage of anti-gliadin antibodies (AGA), introduced in clinical practice in the early 1980s, represents a valuable aid in the screening of patients with suspected gluten-sensitive enteropathy (celiac disease).
In recent years, the importance of anti-gliadin antibodies for the diagnosis of celiac disease has been reduced by the advent of serological markers with greater sensitivity and specificity, such as anti-endomysium autoantibodies (EmA) and anti-transglutaminase autoantibodies (tTGA ).
Celiac disease is a disease triggered by the ingestion of gluten; this protein is mainly contained in wheat, rye, oats and barley. In genetically predisposed subjects, the ingestion of gluten is not tolerated by the intestinal mucosa. This eventuality determines an inflammatory and immune reaction, which thins the intestinal wall and, over time, does not allow the nutrients contained in the food to be properly absorbed. In the organism affected by celiac disease there is also an altered response of the immune system, which determines the formation of auto-antibodies against gluten (called AGA, anti-gliadin antibodies) and against the intestinal mucosa (EMA or tTG).
Celiac disease can affect any age, as it affects children and adults indiscriminately.
Gliadin is a part of gluten, a protein found in almost all cereals (especially wheat, but also rye, oats and barley).
Gliadin is a protein subfraction of gluten; however, it would be more correct to speak of gliadins, since there are different forms or protein components, slightly different from each other and divided into four fractions based on the molecular weight and electrophoretic response: α, Β, γ and ω.
The digestion of gluten ingested with the diet generates peptides (i.e. smaller molecules), such as gliadin, which can induce a specific response by IgG and IgA.
Example of the chemical structure of a wheat gliadin
Anti-gliadin antibodies are autoantibodies produced as part of an immune response against gliadin, which is established in people sensitive to gluten and exposed to it for a certain period of time.
For this reason, gliadin is considered to be one of the major contributors to the abnormal immune response that leads to "atrophy of the intestinal villi in celiac disease. By excluding gluten from the diet of people affected by the disease, there is, in fact, a rapid improvement and recovery. of lesions to the small intestine.
Because it is measured
The AGA assay recognizes the presence of antibodies that trigger the inflammatory and immune reaction underlying celiac disease.
This laboratory test therefore contributes to the diagnosis of celiac disease and allows to monitor the treatment or effectiveness of a gluten-free diet.
The examination is indicated by the doctor in the presence of symptoms that suggest the presence of celiac disease, including:
- Episodes of diarrhea and vomiting;
- Abdominal pain;
- Weight loss;
- Muscle weakness
- Poor appetite.
AGA testing is also useful for diagnosing celiac disease in children under the age of two with dubious or negative anti-transglutaminase (tTG) antibodies, and in cases of IgA deficiency.
Normally, anti-gliadin antibodies are absent (ie the search for AGAs gives a negative result).
The reference values of anti-gliadin antibodies (AGA) may change according to age, gender and equipment used in the individual laboratory. Therefore, it is preferable to consult the ranges provided by the laboratory directly on the report.
AGA Alti - Causes
Anti-gliadin antibodies are moderately elevated or significantly elevated in gluten-sensitive individuals. In general, if the test is positive, celiac disease is likely.
AGA Bassi - Causes
Low levels of anti-gliadin antibodies are not usually associated with medical problems and / or pathological consequences and are therefore not considered clinically relevant.
How it is measured
The search for anti-gliadin antibodies (AGA) is carried out through a simple blood sample to be performed on an empty stomach.
The anti-gliadin antibody assay is a "laboratory test that does not require any specific preparation. The intake of drugs does not affect the outcome of the test, but the doctor may instruct you to fast for at least 8 hours before undergoing the blood sample."
Interpretation of Results
If the anti-gliadin antibody test is "negative" or "absent", it means that the person does not suffer from celiac disease. A "positive" or "present" outcome, on the other hand, indicates the presence of the disease.
However, it should be noted that the test can easily prove positive even in inflammatory bowel diseases not determined by gluten intolerance.