Helicobacter pylori infection: antibodies to Helicobacter pylori in the blood

Normally, IgG antibodies to Helicobacter pylori are not detected in their qualitative determination in serum; In a quantitative study, the IgG antibody titer is less than 8 U / ml, 8-12 U / ml is the "border zone".

Helicobacter pylori - Gram-negative rod, most often having an S-shaped form. Helicobacter pylori occurs on average in 87% of patients with peptic ulcer and 75% of patients with acute gastritis. After penetration of bacteria into the stomach, their adhesion to the cells of the gastric epithelium occurs in the intercellular spaces. The latter is due to bacterial chemotaxis to the urea and hemin yield sites used for the life of bacteria. The urea-cleavable urea is converted into ammonia and carbon dioxide, which create around the bacterial colonies a protective layer that protects them from the unfavorable pH of the gastric juice.

The following diagnostic methods are used to diagnose Helicobacter pylori.

• Bacteriological:
  • detection of bacteria in smears-prints;
  • isolation of the culture of Helicobacter pylori (sensitivity of the method - 33-97%, specificity - 100%).
• Serological: ELISA, immunoblotting.
• Morphological:
  • histological: the detection of bacteria in the biopsy specimen when stained according to Romanovsky-Giemsa, according to Gram, etc. (the sensitivity of the method is 86-99%, specificity is 86-95%);
  • cytological: the study of smears-prints (1-2 or more), obtained from endoscopy from the biopsy specimens of the antrum of the gastric mucosa (sensitivity of the method is 80-90%, specificity is 100%).
• Biochemical:
  • Urease test with biopsy samples (tests of industrial production: CLO-test, De-Nol test, PyloriTek, CUT-test, Help-test, Campy-test, etc.), the sensitivity of the method is 65-95%, specificity - 75-100%;
  • analysis of exhaled air (an air test in which the amount of ammonia in the exhaled air is determined or a more complex analysis of the amount of ¹³ C and ¹⁴ C in the exhaled air after the patient's ingestion of the urea, previously labeled with the indicated isotopes) is made, the sensitivity of the method is up to 99%, the specificity - 98%.
• EIA:
  • Helicobacter pylori detection in feces;
  • the detection of Helicobacter pylori in saliva and gum transess (sensitivity - 66%, specificity - 66.7%).
• PCR.

The most widely used serological method for the diagnosis of Helicobacter pylori is ELISA. The method is non-invasive and indirect: in the patient's blood, antibodies to Helicobacter pylori, attributed to IgA, IgM and (most often) IgG are determined . When using this method in the total antibody titer, the most valuable is the determination of IgG antibody titer for Helicobacter pylori. The sensitivity of the method ranges from 87% to 98%, specificity - 75-100%. A simple qualitative determination of antibodies to Helicobacter pylori by ELISA is used mainly to diagnose infection.

In recent years, diagnostic test systems based on ELISA, possessing high sensitivity and allowing quantitative determination of antibodies to Helicobacter pylori of various classes have been obtained . Such test systems can be used to assess eradication. It has been shown in comparison with invasive methods (histological, urease) that if after 30-40 days after treatment the IgG antibody titer is reduced by 20% or more, it can be considered that as a result of treatment Helicobacter pylori eradication occurred if the titer value increased, does not change, or its reduction is less than 20%, it should be regarded as the absence of eradication.

Determination of the antibody titer to Helicobacter pylori is necessary for diagnosis of diseases caused by Helicobacter pylori, including ulcerative disease of the stomach and duodenum, stomach cancer, ulcer of the esophagus.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]