title: Increased mucosal production of monomeric IgA1 but no IgA1 protease activity in Helicobacter pylori gastritis.
abstract: Immunoglobulin A and IgM are subjected to epithelial transport only when they are produced as polymers with incorporated J chain. Immunocytes containing various Ig isotypes and associated J chain in gastric mucosa, as well as IgA-degrading protease activity in Helicobacter pylori cultures, were examined. Gastric body specimens from 15 H. pylori-positive and 14 H. pylori-negative patients were studied by paired immunofluorescence for IgA, IgA1, IgA2, IgG, or IgM and concurrent cellular J chain. H. pylori isolates were incubated with IgA1 or secretory IgA and examined by immunoelectrophoresis for cleavage products. A substantial increase of Ig-producing cells occurred in chronic gastritis, particularly in the IgA1 isotype, but H. pylori was shown to possess neither IgA1-specific nor nonspecific IgA-degrading protease activity. Regardless of infection status, reduced J chain expression was observed for all immunocyte isotypes (except for IgM) in inflamed compared with normal gastric body mucosa, the median positivity for IgA1 cells being reduced to 58.7% versus 87.9% (P = 0.0002), and for IgA2 cells to 48.9% versus 87.8% (P = 0.0002). This down-regulation of the J chain suggested that a large fraction of IgA monomers is produced in gastritis.
authors.affiliation: Laboratory for Immunohistochemistry, Institute of Pathology, University of Oslo, Oslo, Norway. audun.berstad@rh.uio.no
authors.forename: A E
authors.initials: AE
authors.lastname: Berstad
authors.forename: M
authors.initials: M
authors.lastname: Kilian
authors.forename: K N
authors.initials: KN
authors.lastname: Valnes
authors.forename: P
authors.initials: P
authors.lastname: Brandtzaeg
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D005260:Female; D005753:Gastric Mucosa / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000382:microbiology*; D005756:Gastritis / Q000201:enzymology / Q000276:immunology / Q000382:microbiology* / Q000473:pathology; D016481:Helicobacter Infections / Q000201:enzymology*; D016480:Helicobacter pylori / Q000201:enzymology* / Q000302:isolation & purification; D006801:Humans; D007070:Immunoglobulin A / Q000096:biosynthesis* / Q000378:metabolism; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D007144:Immunoglobulin J-Chains / Q000096:biosynthesis; D007962:Leukocytes / Q000166:cytology / Q000378:metabolism; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D012697:Serine Endopeptidases / Q000378:metabolism*; D014510:Urease / Q000378:metabolism
chemical_list: D007070:Immunoglobulin A; D007071:Immunoglobulin A, Secretory; D007144:Immunoglobulin J-Chains; D012697:Serine Endopeptidases; C021433:IgA-specific serine endopeptidase; D014510:Urease