CagA IgG EIA WELL REF K6HPG - Radim S.p.A.

ENZYME IMMUNOASSAY FOR QUANTITATIVE DETERMINATION OF ANTI-
CagA IgG ANTIBODIES IN HUMAN SERUM OR PLASMA.
FOR IN VITRO DIAGNOSTIC USE ONLY
1. CLINICAL APPLICATIONS
Helicobacter pylori is a small, S-shaped gram-negative bacterium that infects the
gastric mucosa in 20-80% of the human population. The prevalence of H. pylori
infection increases with age and depends on several factors, such as geographic
area and socioeconomic status. This bacterium causes chronic as well as acute
gastritis, peptic ulcer disease, atrophic gastritis and it is suspected to have a role
in gastric adenocarcinoma. H. pylori infection persists throughout lifetime, when
not eradicated by specific antibiotic treatment. In patients with gastric or duodenal
ulcers, H. pylori eradication results in a marked reduction of the recurrence rate.
Nevertheless, although nearly all infected individuals develop gastritis, it remains
unclear why most H. pylori-infected patients remain asymptomatic. In fact, it is
only in a minority of these patients that the infection leads to gastric or duodenal
ulcer. This may be due to several host factors (smoking, 0 blood type, male
gender) and also to the heterogeneity among H. pylori strains. It has recently
been discovered that approximately 50 to 60 % of H. pylori strains produce a 87
kDa vacuolating cytotoxin (VacA) together with a highly antigenic protein of about
120-128 kDa (CagA). On the other hand, strains that do not produce the cytotoxin
do have the cytotoxin gene but lack the gene coding for CagA. Several studies
have demonstrated that cytotoxin producing strains are isolated more frequently
from subjects with peptic ulcer disease, rather than from subjects with non-ulcer
dyspepsia. In serological studies, IgG against CagA have been detected in H.
pylori-infected subjects with peptic ulcer disease much more recurrently than in
infected individuals, with mere gastritis. Accordingly, the detection of anti-CagA
IgG in patient serum indicates previous infection by a CagA-positive H. pylori
strain. This may be a helpful tool in therapeutical decisions.
2. PRINCIPLE OF THE ASSAY
This kit is based upon an enzyme immunoassay method (ELISA), where
horseradish peroxidase is used as enzyme conjugate. During the first incubation,
the sample anti-CagA IgG antibodies, if any, are bound to the CagA antigen
coated wells. A wash cycle eliminates all unbound material. In the incubation that
follows, a second antibody (anti-human IgG conjugated with peroxidase) will bind
to the CagA-antigen-antibody complex. After a further wash cycle a colorless
Chromogen solution (tetramethylbenzidine, TMB) in a substrate-buffer is added to
the wells, where it yields a colored compound, by reacting with the peroxidase
enzyme. Color development will be stopped by adding H2SO4. The color intensity,
measured in a spectrophotometer at 450 and 405 nm, will thus be directly
proportional to the anti-CagA IgG antibody concentration in calibrators and
samples.
K6HPG –CagA IgG EIA WELL
M197 – Rev.9 – 06/2008 – Pag. 12/ 24