Development and clinical application of an immunoassay using intact Helicobacter pylori attached to a solid phase as an antigen

Objective: At present, H. pylori homogenates, extracts and recombinant proteins are used as antigens in immunoassays, but significant false positive and negative results are obtained. We attempted to develop an ELISA system using immobilized whole intact H. pylori cells as a solid phase antigen (WIC-ELISA) which specifically recognizes surface antigens. Methods: intact H. pylori cells were immobilized on ELISA plates by centrifugation (150 g for 10 min). HRP-labeled antihuman Ige was used as the second antibody. H. pylori-infections were investigated with WIC-ELISA and a conventional method in which H. pylori-extracts were used as antigen in 117 patients. Results: WIC-ELISA showed better characteristics than conventional ELISA in regards to sensitivity (98.9 vs. 90.4%), specificity (95.7 vs. 95.7%), positive predictive value (98.9 vs. 98.8%), negative predictive value (95.7 vs. 71.0%) and accuracy (98.3 vs. 91.5%). Conclusions: WIC-ELISA is useful for quantification of antibodies against H. pylori surface antigens and as a clinical screening test. (C) 2001 The Canadian Society of Clinical Chemists. All rights reserved.