Improved Histologic Identification ofHelicobacter pyloriby Immunohistochemistry Using a New Novocastra Monoclonal Antibody

Gastric infection with Helicobacter pylori is associated with many upper gastrointestinal diseases including H. pylori-associated gastritis, and it is standard practice to routinely perform histochemical or immunohistochemical stains on endoscopic gastric biopsies. Several studies have shown that immunohistochemical staining with specific H. pylori antibodies shows the highest sensitivity and specificity in detecting H. pylori. This study was conducted to compare a new Novocastra monoclonal antibody, clone UCL3R, to a polyclonal antibody, NCL-HPp, in known cases of H. pylori infection of the stomach. The following 3 performance characteristics were assessed: sensitivity, quality of organism morphology, and non-specific background staining. Two pathologists with expertise in gastrointestinal pathology examined 300 biopsies that previously demonstrated H. pylori gastritis using the polyclonal antibody immunohistochemical method (NCL-HPp). The sensitivity of the 2 methods was comparable with 96.2% of the cases identified by the monoclonal antibody method and 98.5% identified by the polyclonal antibody method. The pathologists scored the 2 methods for quality of organism morphology and background staining. The data showed the monoclonal method was superior for quality of organism morphology and background staining. The sensitivity of the 2 methods was comparable with 96.2% of the cases identified by the monoclonal method and 98.5% identified by the polyclonal method and the specificity was 100%. The new H. pylori monoclonal antibody shows improved quality of organism morphology and reduced background staining compared to the polyclonal antibody.