title: Interleukin-6 and small intestinal luminal immunoglobulins.
abstract: Our aim was to determine the relationships between interleukin-6 and immunoglobulin levels within small intestinal luminal secretions. Twenty adult subjects with small intestinal bacterial overgrowth (N = 13), irritable bowel syndrome (N = 4), and nonulcer dyspepsia (N = 3) underwent endoscopic aspiration of secretions from the small intestinal mucosal surface for assessment of IL-6, IgA1, IgA2, IgM, IgG1, IgG2, IgG3, and IgG4 concentrations. Serum immunoglobulin concentrations and small intestinal histology were also determined. IgA2 and IgG3 were the predominant IgA and IgG subclasses in luminal secretions in 19/20 (95%) and 20/20 (100%) subjects, respectively. IgA1 and IgG1 predominated in serum in all subjects. No subject had villous atrophy. Luminal IL-6 concentrations correlated significantly with luminal IgA2, IgM, and IgG3 concentrations but not with IgA1 or any other IgG subclass levels. Conversely, luminal IL-6 or immunoglobulin concentrations did not correlate significantly with levels of any immunoglobulin isotype in serum. These observations suggest that important relationships exist between local IL-6 and IgA2, IgM, and IgG3 responses in human small intestinal luminal secretions. Local investigation is mandatory when assessing intestinal immune activity.
authors.affiliation: Department of Gastroenterology, The Prince of Wales Hospital, University of New South Wales, Sydney, Australia.
authors.forename: S M
authors.initials: SM
authors.lastname: Riordan
authors.forename: C J
authors.initials: CJ
authors.lastname: McIver
authors.forename: D
authors.initials: D
authors.lastname: Wakefield
authors.forename: M C
authors.initials: MC
authors.lastname: Thomas
authors.forename: V M
authors.initials: VM
authors.lastname: Duncombe
authors.forename: T D
authors.initials: TD
authors.lastname: Bolin
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003109:Colonic Diseases, Functional / Q000276:immunology; D003967:Diarrhea / Q000276:immunology; D004415:Dyspepsia / Q000276:immunology; D006801:Humans; D007136:Immunoglobulins / Q000032:analysis*; D015850:Interleukin-6 / Q000032:analysis*; D007410:Intestinal Diseases / Q000276:immunology*; D007413:Intestinal Mucosa / Q000276:immunology; D007421:Intestine, Small / Q000276:immunology*; D016014:Linear Models; D008875:Middle Aged
chemical_list: D007136:Immunoglobulins; D015850:Interleukin-6