PARTICLE AGGLUTINATION ASSAY FOR DETECTION OF ALBUMIN AND IGG BINDING-CELL SURFACE COMPONENTS OF HELICOBACTER-PYLORI

Human serum albumin (HSA), bovine serum albumin (BSA) and human Ige we re immobilized on latex beads to detect cell surface components of Hel icobacter pylori binding to BSA, HSA, and IgG by a particle agglutinat ion assay (PAA). In a total of 32 H. pylori strains tested, 16 strains interacted with BSA and 12 strains with HSA; 24 strains expressed bin ding of human IgG. The specificity of the agglutination reaction was s tudied by a particle agglutination inhibition assay performed by pre-i ncubating bacterial cell suspensions in buffers containing homologous proteins, unrelated glycoproteins and a number of common monosaccharid es. Treatment of H. pylori cells with heat and proteolytic enzymes abo lished binding to microbeads with immobilized IgG and albumin. IgG-bin ding surface components from cells of H. pylori strain CCUG 17875 were effectively extracted by incubating a cell suspension with 10 mM EDTA , 0.015 M sodium phosphate buffer (pH 7.2), and by washing H. pylori c ells with distilled water. However, attempts to extract a fraction ric h in albumin-binding components were unsuccessful. We conclude that ce lls of various H. pylori strains express commonly IgG-binding proteins , and that albumin-binding is probably mediated by non-specific hydrop hobic interactions.