Antibodies to endomysis of classes such as IgG and IgA are the most accurate diagnostic test for celiac disease; they can be detected in 95% of people with this disease. Their determination becomes possible with Dühring herpetiform dermatitis, which often accompanies celiac disease.
Description
By endomysium is meant a type of connective tissue that consists of a third type of collagen and partly of the first type of collagen. This tissue surrounds the muscle fibers in the wall of the small intestine. If people are genetically predisposed to celiac disease, then ingestion of gluten with food causes the development of immune inflammation with the formation of antibodies to gliadin, a component of gluten, as well as antibodies to intestinal wall structures - reticulin, endomysia.
As a result, the inflammatory reaction leads to atrophy of the villi in the small intestine, which are responsible for the absorption of nutrients. A 1997 Dieterich study showed that the formation of antibodies to endomysium occurs to a specific enzyme, not endomysium in general, to TSH, i.e. tissue transglutaminase. Five types of enzyme are known. A second type of TSH was found in the stomach, and a third in the skin. This can explain the finding of antibodies to endomysia in celiac disease and herpetiform dermatitis, and not to individual fractions. In the body of patients with celiac disease, an excessive concentration of TSH is observed in all layers of the intestinal mucosa.
With a comprehensive diagnosis of the disease, it is recommended first of all to determine the presence of antibodies to gliadin in the blood, then antibodies to endomysium and reticulin. If necessary, select the most informative test to determine the antibodies of classes IgG and IgA to endomysium. An accurate diagnosis of “celiac disease” in any case is only authorized after an intestinal endoscopy with a villus biopsy. Such a diagnosis is still used to evaluate the effectiveness of therapy.
Gluten free diet
When the patient switches to a gluten-free diet, all types of antibodies (to endomysium, reticulin and gliadin) go out of the blood after a few months if you eat foods that do not contain gluten. When diagnosing celiac enteropathy (celiac disease), you need to remember the genetic factor in the development of pathology, therefore, if the diagnosis is confirmed in one family member, close relatives should be examined, since celiac disease can occur secretly in them.
Tissue transglutaminase acts as the main antigen for antibodies to endomysia, if the patient has celiac disease. In this case, antigens are located in the umbilical cord, esophagus, liver, stomach and other tissues of primates and humans. These tissues can be used as an antigenic substrate for immunological fluorescence studies.
Celiac disease: definition
Celiac disease is characterized by digestive disorders due to damage to the mucous membrane of the small intestine. When celiac disease does not tolerate cereal protein - gliadin (gluten), an autoimmune reaction develops with the formation of antibodies to its own proteins. With gluten enteropathy, the villi of the intestinal mucosa become inflamed, as a result, there is a violation of the processes of digestion and absorption, which causes the main symptoms of the pathology. An important role in the development of the disease is played by other factors - genetic, allergic reactions. Signs begin to appear even in childhood, when products from barley, oats, rye, wheat and other cereals saturated with gluten, that is, cereal, in the form of complementary foods appear in the baby's diet. This happens from about 6-8 months. The culmination of the incidence falls on the age of four to six years. In the treatment of the disease, an important role is given to the patient's gluten-free diet.
In what cases should blood donate for antibodies to endomysia?
Symptoms of Celiac Disease
The main manifestations of celiac disease:
- vomiting and nausea, constipation, flatulence;
- diarrhea, which is accompanied by a strong foamy, pasty, grayish stool;
- a delay in physical development and growth in children, loss of body weight with a simultaneous increase in the size of the abdomen;
- osteoporosis;
- anemia;
- herpetiform dermatitis (or “skin” type of celiac disease) - a rash with spots with blisters mainly on the trunk, extensor surfaces of the limbs, neck, scalp, itching;
- neurological symptoms.
Indications for analysis
Indications for the analysis of antibodies to endomysium are as follows:
- Definition of celiac disease in babies with foamy stools, flatulence, poor weight gain.
- Diagnosis of the disease in adults with signs of malabsorption (malabsorption syndrome): weight loss, diarrhea, vitamin deficiency, hypocalcemia, anemia.
- Determination of adult celiac disease with a hereditary IgA deficiency and herpetiform dermatitis.
- Evaluation of the effectiveness of celiac disease therapy.
- Determination of celiac disease in relatives.
How to prepare for the study?
It is necessary to exclude the use of alcoholic beverages a day before the study of antibodies to endomysium and tissue transglutaminase. One hour before taking blood for smoking is prohibited. They donate blood for examination on an empty stomach in the morning, not even coffee or tea are allowed. Only plain water is allowed. At least eight hours should elapse between the last meal and the test. Ten minutes before the study, the patient needs to be at rest, both physical and emotional.
Interpretation of Results
If IgA antibodies to tissue transglutaminase and endomysium are increased, consultation with a pediatrician or gastroenterologist and a small intestine biopsy are required. In accordance with the latest studies on the diagnosis of celiac disease, in some situations it is possible to refuse a small intestine biopsy to confirm the diagnosis, when the child has severe clinical signs, high EMA IgA and tTG IgA, he acts as a carrier of HLA-DQ2 / DQ8.
The establishment of EMA IgA antibodies is allowed for diagnosis in children of celiac disease after two years of age and in adults. To determine celiac disease in children under two years of age, it is preferable to test for antibodies of classes IgG and IgA to S-AGA IgA (deamidated gliadin), sensitivity from 98 to 100%, as well as S-AGA IgG (IgG antibodies) with sensitivity from 96 to 100 %. The sensitivity of EMA IgA antibodies at this age is low.
If celiac disease is suspected, if the test for TtG IgA and EMA IgA is negative, the serum immunoglobulin S-IgA (A) should be determined.
In patients with a predefined IgA deficiency, for the diagnosis and monitoring of the disease, it is necessary to detect the presence of antibodies of the IgG class: S-AGA IgG, S-EMA IgG or S-tTG IgG, because these patients do not synthesize IgA class autoantibodies.
The sensitivity of tests for antibodies to tissue transglutaminase in the screening diagnosis of celiac disease ranges from 85 to 98%, the specificity value is from 95 to 99%.
If the test results are negative and there is still a suspicion of celiac disease, a blood test for antibodies to endomysium and tissue transglutaminase should be repeated after three to six months.
What can affect the result of the analysis?
The content of S-AGA IgA, S-tTG IgA or EMA IgA in the blood serum decreases with a gluten-free diet after two to three months, the concentration of antibodies rises again when the diet is broken or stopped. A false-positive result can be with malabsorption, which appeared against a background of chronic infection, Crohn's disease, with protein intolerance (milk, egg). In rare cases, a false-positive result can be observed in healthy people.
Where is the analysis given?
Diagnostics of celiac disease in various Russian cities is carried out not only by the diagnostic network institutions Invitro or Helix, the medical laboratory Gemotest, but also by non-network small laboratories, including those located in municipal medical institutions.
An analysis to determine the antibodies to endomysium in Invitro costs about 1150 rubles. Duration - from 7 to 14 days.
The study of antibodies to endomysium in the Hemotest can be carried out for 1200 rubles. The deadline is 14 days.
Other methods of diagnosing a pathology such as celiac disease in the laboratory
The specific immunodiagnosis of celiac disease is highlighted - the definition of autoimmune bodies that are characteristic of celiac disease.
Antibodies to reticulin (ARA - anti-reticulin antibodies) such as IgG and IgA. Serological tests in children under five years of age with celiac disease are less reliable and are not intended for diagnosis. With a gluten-free diet, specific antibodies to gliadin disappear. Therefore, in order to confirm the diagnosis, at least during the week in preparation for the study, products that contain gluten must be included in the patient's diet. Or immunological studies should be prescribed before a gluten-free diet was introduced. Such studies can also be used to monitor therapeutic efficacy (a decrease in the dynamics of antibody titer). In addition, biopsy of the small intestine mucosa, that is, the gold standard of diagnosis, is of particular importance in the diagnosis of celiac enteropathy.
Such a diagnosis as celiac disease is made in the presence of pathological changes revealed during the biopsy - crypt hyperplasia, villous atrophy and identification of the symptoms of immune inflammation (accumulation in the mucous membrane of lymphocytes) + at least two types of antibodies in the blood serum in high titers. There is also a diagnosis of a hereditary predisposition to the disease - the identification of the HLA DQ8 and HLA DQ2 genes. About 20-25% of people have DQ8 or DQ2 antigens, and patients with celiac disease have DQ8 and / or DQ2 markers (more than 97%).
General laboratory tests that confirm indirectly such a diagnosis as celiac disease:
- blood serum albumin test and total protein;
- general blood analysis;
- fecal analysis (coprogram);
- analysis for electrolytes - chlorine, potassium, sodium;
- total IgA level;
- measurement of calcium;
- blood cholesterol and lipid levels;
- study of alkaline phosphatase;
- blood serum iron.
We examined what antibodies to endomysium show.