Back to Search
Start Over
The Human Gastrointestinal Secretory Immune System in Health and Disease
- Source :
- Scandinavian Journal of Gastroenterology. 20:17-38
- Publication Year :
- 1985
- Publisher :
- Informa UK Limited, 1985.
-
Abstract
- The main function of secretory IgA is to exert immune exclusion; that is, by intimate cooperation with innate non-specific defence mechanisms, it dampens down penetration of soluble antigens and inhibits epithelial colonisation of bacteria and viruses. Secretory IgM may exert a similar protective function in the gut as its local synthesis sometimes is markedly increased, especially in selective IgA deficiency. IgG should not be considered a secretory immunoglobulin because its external translocation depends on passive intercellular diffusion. By activating complement, antibodies of this isotype may cause increased mucosal permeability and tissue damage. IgG may thus contribute to persistent immunopathology in mucosal lesions. The same is true for IgE antibodies which, in atopic individuals, may be carried into the gut mucosa by mast cells and cause their degranulation with histamine release. Secretory IgA and secretory IgM are the products of two cell types: plasma cells synthesise IgA dimers and IgM pentamers which, by non-covalent association, become complexed with the secretory component (SC) which is synthesized by serous-type glandular cells. The adsorption of the Ig polymers to the SC-expressing epithelial cells depends on J chain-determined binding sites. This fact gives biological significance to the striking J chain expression shown by mucosal immunocytes regardless of the Ig class they produce. The immunocytes populating the gut mucosa apparently belong to relatively early memory B cell clones. The obvious functional goal of J chain expression at this stage of clonal differentiation is local generation of SC-binding IgA and IgM polymers. In various gut diseases, altered immune regulation results in a disproportionately increased number of J chain-negative IgG-producing cells in the mucosa. Such altered immunological homeostasis may contribute to perpetuation of inflammatory bowel diseases.
- Subjects :
- Adult
Gastrointestinal Diseases
Lymphoid Tissue
T-Lymphocytes
Selective IgA deficiency
Immunoglobulin E
Microbiology
chemistry.chemical_compound
Immune system
Crohn Disease
Antigen
HLA Antigens
Immunopathology
medicine
Humans
Intestinal Mucosa
Child
biology
Gastroenterology
medicine.disease
Isotype
Secretory Component
Celiac Disease
Immunoglobulin M
chemistry
Gastritis
Immune System
Immunoglobulin A, Secretory
Immunology
biology.protein
Colitis, Ulcerative
Antibody
Digestive System
Histamine
Subjects
Details
- ISSN :
- 15027708 and 00365521
- Volume :
- 20
- Database :
- OpenAIRE
- Journal :
- Scandinavian Journal of Gastroenterology
- Accession number :
- edsair.doi.dedup.....4d93d778c8d80a47d70bacbbaf66b446