Identification of cells producing antibodies specific for Helicobacter pylori in chronic atrophic gastritis : Application of the enzyme-labeled antigen method.

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It has been suggested that infection of Helicobacter pylori is pathogenic for chronic atrophic gastritis. However, no infection is demonstrated on the surface of intestinal metaplasia. The present study was aimed at identifying plasma cells producing antibodies specific for H.pylori in the mucosa with chronic atrophic gastritis by using "the enzyme-labeled antigen method". [Materials and Methods] Fresh gastric mucosa was sampled. We tried to prepare the labeled antigen in the following three approaches : A) Purification and biotinylation of urease, B) synthesis of biotinylated polypeptides from the known urease amino acid sequence. c) Production of recombinant protein of maltose-binding protein (MBP) and bacterial protein. [Results] Methods for histochemical detection of H.pylori was established. However, it was very difficult to prepare the labeled antigen. The methods A) and B) failed to be achieved. A preliminary study of "the enzyme-labeled antigen method" by using a biotinylated crude bacterial extract revealed no specific findings. Thus, with the method C), a recombinant fusion protein (M.W.60kD) was obtained by inserting a bacterial DNA fragment in the MBP-vector. The MBP-labeled protein showed a reactivity with the patient serum, but, regretably enough, it was of no use for detecting the specific antibody-producing cells in frozen sections. [Comments] The present study was unique in that the site of antibody production be visualized in the gastric mucosa by the novel technology. The preparation of the labeled antigen should be the starting point of study. We are now further trying to establish this approach for clarifying the pathogenesis of the bacteria in a chronic inflammatory process in the gastric mucosa.