HP IgA
Enzyme ImmunoAssay (ELISA) for the quantitative/qualitative determination of IgA antibodies to Helicobacter pylori in human plasma and sera. The product is intended for the follow-up of patients showing gastrointestinal pathologies referable to H.pylori infection.
Helicobacter pylori (HP) is a Gram negative bacterium, firstly isolated in gastric mucosa by Marshall and Warren in 1983.
Hp has been recognized to be the agent responsible of most of cases of gastric mucosal damage and to play a role in the evolution of gastric diseases to carcinoma.
Hp causes an immunological response during infection and specific antibodies of the different classes of IgG, IgA and IgM are produced by the patient.
ELISA are currently used to screen patients affected by gastritis or peptic ulcers for acute active infection due to some Helicobacter pylori virulent strains.
In particular the presence of IgA and IgM antibodies is reported to be correlated to the acute phase of illness, while IgG antibodies become present at different titers shortly after primary infections and last in blood for many years.
Quantitative ELISA are also used in the follow-up of patients undergoing antibiotic therapy, useful in monitoring IgG titer variations during and after the pharmaceutical treatment
Microplates are coated with H.pylori immunodominant antigens derived from tissue culture of a virulent strain.
In the 1st incubation, the solid phase is treated with diluted samples and anti-HP IgA are captured, if present, by the antigens.
After washing out all the other components of the sample, in the 2nd incubation bound anti-HP IgA are detected by the addition of anti hIgA antibody, labeled with peroxidase (HRP).
The enzyme captured on the solid phase, acting on the substrate/chromogen mixture, generates an optical signal that is proportional to the amount of anti-HP IgA antibodies present in the sample.
IgA in the sample may therefore be quantitated by means of a standard curve calibrated in arbitrary units per milliliter (arbU/ml) as no international standard is available. Neutralization of IgG anti-HP, carried out directly in the well, is performed in the assay in order to block interferences due to this class in the determination of IgA.
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