Helicobacter pylori IgA ELISA
The IMMUNOLAB Helicobacter pylori IgA Antibody ELISA Test Kit has been designed for the the detection and the quantitative determination of specific IgA antibodies against Helicobacter pylori in serum and plasma. Further applications in other body fluids are possible and can be requested from the Technical Service of IMMUNOLAB.
Helicobacter pylori, a 2.5-3 μm long, twisted or helical gram-negative germ is responsible for 80- 90% of B-gastritis cases and is suspected to be a major cofactor for the development of gastric and duodenal ulcers. Up to now Helicobacter pylori could be most reliably detected by culturing from mucous membrane biopsies; also a urease test was employed for identification. These detection methods are only successful for a relatively high germ count from the inoculate and require an identification directly after taking the biopsy. Recently it was shown that a detection of Helicobacter pylori by indirect immunofluorescence (IIF) should be superior to the above methods. The identification by IIF is also advantageous as it is not necessary to perform the determination directly after the biopsy; thus preparations can be sent to specialized laboratories. The colonisation of the gastric and duodenal mucous membranes by Helicobacter pylori can also be detected serologically by the performance of an enzyme immunoassay (ELISA) or by Western Blot. Patients with confirmed exposition to Helicobacter pylori often show a positive serological result. Since antibodies persist for a longer time after a Helicobacter pylori infection, seropositive individuals are also found among symptom-free patients. The ratio of seropositive values rises with age. By the determination of immunoglobulins in ELISA and by the detection of IgG, IgA and IgM antibodies against specific proteins of Helicobacter pylori in the Western Blot, it should be possible to diagnose an acute infection with Helicobacter pylori, even if no germs can be found. The detection of Helicobacter pylori is of remarkable interest for the therapy. Bismuth salts and antibiotics use to kill the germs, and these should complement or replace the usual therapy with antacidic and H2 blocking agents. Serological monitoring could thus also be employed to control the success of antimicrobial therapy.
The IMMUNOLAB Helicobacter pylori IgA antibody test kit is based on the principle of the enzyme immunoassay (EIA). Helicobacter antigen is bound on the surface of the microtiter strips. Diluted patient serum or ready-to-use standards are pipetted into the wells of the microtiter plate. A binding between the IgA antibodies of the serum and the immobilized Helicobacter antigen takes place. After a one hour incubation at room temperature, the plate is rinsed with diluted wash solution, in order to remove unbound material. Then ready-to-use anti-human-IgA peroxidase conjugate is added and incubated for 30 minutes. After a further washing step, the substrate (TMB) solution is pipetted and incubated for 20 minutes, inducing the development of a blue dye in the wells. The color development is terminated by the addition of a stop solution, which changes the color from blue to yellow. The resulting dye is measured spectrophotometrically at the wavelength of 450 nm. The concentration of the IgA antibodies is directly proportional to the intensity of the color.
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