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 prot eins are used as antigens in immunoassays, but significant false positive a nd negative results are obtained. We attempted to develop an ELISA system u sing 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 centrif ugation (150 g for 10 min). HRP-labeled antihuman Ige was used as the secon d antibody. H. pylori-infections were investigated with WIC-ELISA and a con ventional method in which H. pylori-extracts were used as antigen in 117 pa tients. Results: WIC-ELISA showed better characteristics than conventional ELISA in regards to sensitivity (98.9 vs. 90.4%), specificity (95.7 vs. 95.7%), pos itive 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 Ca nadian Society of Clinical Chemists. All rights reserved.