title: Orchestrated leukocyte recruitment to immune-privileged sites: absolute barriers versus educational gates.
abstract: Complex barriers separate immune-privileged tissues from the circulation. Here, we propose that cell entry to immune-privileged sites through barriers composed of tight junction-interconnected endothelium is associated with destructive inflammation, whereas border structures comprised of fenestrated vasculature enveloped by tightly regulated epithelium serve as active and selective immune-skewing gates in the steady state. Based on emerging knowledge of the central nervous system and information from other immune-privileged sites, we propose that these sites are endowed either with absolute endothelial-based barriers and epithelial gates that enable selective and educative transfer of trafficking leukocytes or with selective epithelial gates only.
authors: Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
authors: Ravid
authors: R
authors: Shechter
authors: Anat
authors: A
authors: London
authors: Michal
authors: M
authors: Schwartz
mesh_terms: D000818:Animals; D018916:Blood-Aqueous Barrier / Q000276:immunology / Q000502:physiology; D001812:Blood-Brain Barrier / Q000276:immunology / Q000502:physiology; D001813:Blood-Retinal Barrier / Q000276:immunology / Q000502:physiology; D001814:Blood-Testis Barrier / Q000276:immunology / Q000502:physiology; D002459:Cell Fusion; D002634:Chemotaxis, Leukocyte; D046528:Chimerism; D004847:Epithelial Cells / Q000502:physiology / Q000648:ultrastructure; D004848:Epithelium / Q000276:immunology / Q000502:physiology; D005260:Female; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology; D007157:Immunologic Surveillance / Q000276:immunology / Q000502:physiology*; D007249:Inflammation / Q000276:immunology / Q000503:physiopathology; D008297:Male; D008431:Maternal-Fetal Exchange / Q000276:immunology; D018448:Models, Immunological; D020556:Neutrophil Infiltration; D009928:Organ Specificity; D011247:Pregnancy; D019108:Tight Junctions / Q000502:physiology*; D057705:Transendothelial and Transepithelial Migration / Q000502:physiology