PARTIAL CHARACTERIZATION OF AN EXTERNAL POLYSACCHARIDE OF HELICOBACTER-PYLORI BY USING AN IMMUNOGLOBULIN-M MONOCLONAL-ANTIBODY

A monoclonal immunoglobulin M antibody, HP15/36, was produced by a hyb ridoma cell line prepared by fusion of mouse myeloma cell line Sp2/O w ith spleen cells of mice immunized with Helicobacter pylori D273 (Fren ch strain). Immunoelectron microscopy of whole bacteria and ultrathin sections showed that the determinant was located outside the bacterial cell, possibly in the outermost areas. This external reactivity was o bserved by immunofluorescence and immunoperoxidase assays and was conf irmed by immunogold study at the ultrastructural level. The reactive e pitope was formol and picric acid resistant and allowed the detection of the bacterium on fixed tissue biopsy specimens. The reactive compon ent was extracted with phenol-water. Immunoblotting with such an antig en exhibited a clearly positive reactivity at a molecular mass between 50 and 120 kDa. This reactivity was suppressed by periodate oxidation , suggesting a carbohydrate epitope. The diagnostic value and signific ance of this polysaccharide in microbe-host interactions remain to be determined.