Immunocytochemical identification of Helicobacter pylori in formalin-fixed gastric biopsies

H&E and special histochemical stains are used by most laboratories to identify Helicobacter pylori (H. pylori) in gastric biopsy specimens. However, background staining can complicate recognition of H. pylori and small numbers of organisms may be overlooked. Additionally, histochemical stains do not distinguish H. pylori from other spiral organisms. We investigated two commercially available monoclonal antibodies, one directed against Campylobacter coli and C. jejuni (MAB002) and the other against a Campylobacter species flagellar antigen (MAB001), to evaluate potential use in immunocytochemical examinations of fixed tissues. MAB002 reacted with C. jejuni but not H. pylori organisms. MAB001 labeled C. jejuni as well as H. pylori and, therefore, was used to study 220 gastric biopsies from patients undergoing endoscopy. Acute and/or chronic gastritis was present in 60.5% (133/220) of the biopsies examined. MAB001 positivity was identified in 62.4% (83/133) of the tissues with gastritis. Only 2 of 87 (2.3%) specimens without gastritis demonstrated MAB001 labeling. The resulting immunoreactivity was easily identified, allowing specimens to be screened quickly and accurately. No labeling was seen with the non-Helicobacter/Campylobacter bacteria or normal tissues evaluated in this investigation. MAB001 can be used to identify H. pylori in histologically processed tissue and will assist pathologists, clinicians, and researchers studying the distribution and pathogenicity of this organism in humans and animals.