title: Ontogenetic aspects of the intestinal immune system in man.
abstract: The development of the mucosal immune system in the human fetus has been studied in some detail. Aggregates of T and B cells form early Peyer's patches by 16 weeks gestation and by 19 weeks organised Peyer's patches with T and B cell zones are seen. T cells populate the mucosal lamina propria and epithelium from 11 weeks gestation and increase in number thereafter. As in the adult, most intraepithelial lymphocytes are CD8+ and most lamina propria T cells are CD4+. By 20 weeks, villus epithelial cells are HLA-DR+ and secretory component is also expressed. In the absence of lumenal stimulation in the fetus there is no intestinal secretory IgA antibody response. A few IgA plasma cells are present in fetal salivary glands but the number does not dramatically increase until after birth.
authors.forename: C P
authors.initials: CP
authors.lastname: Braegger
authors.forename: J
authors.initials: J
authors.lastname: Spencer
authors.forename: T T
authors.initials: TT
authors.lastname: MacDonald
mesh_terms: D005314:Embryonic and Fetal Development / Q000276:immunology; D004847:Epithelial Cells; D004848:Epithelium / Q000196:embryology; D000949:Histocompatibility Antigens Class II / Q000032:analysis; D006801:Humans; D007107:Immune System / Q000196:embryology*; D007413:Intestinal Mucosa / Q000196:embryology / Q000276:immunology*; D008214:Lymphocytes / Q000276:immunology; D008221:Lymphoid Tissue / Q000196:embryology; D010581:Peyer's Patches / Q000196:embryology; D012469:Salivary Glands / Q000196:embryology / Q000276:immunology; D012635:Secretory Component / Q000032:analysis
chemical_list: D000949:Histocompatibility Antigens Class II; D012635:Secretory Component