immunology Flashcards
what is the first solution of the innate immune system of the eye?
blink reflex and physical properties of the eye surface- tears also flush out objects
describe the chemical properties of the eye surface
tears- chemical
Lysozyme: v. gram –ve bacteria, fungi (destroy bacteria cell wall)
Lactoferrin and transferrin: v. gram +ve bacteria
Tear lipids: antibacterial to cell membranes/scavenger of bacterial products
Angiogenin: antimicrobial effect within tear film
Secretory IgA: prevents attachment
Complement
IL-6, IL-8, MIP: antimicrobial molecules that recruit leucocytes
describe the immune cells of the eye
Neutrophils:
Attracted by chemotaxis
Scavengers – release free radicals, enzymes
Macrophages:
Phagocytosis of damaged cells
Help to trigger adaptive immune system
Conjunctival mast cells:
Vasoactive mediators
what does the adaptive immune system of the eye require?
Antigen presenting cells
Lymphatic drainage to lymph node
Variety of effector cells
what is the only part of the eye with lymphatic drainage?
conjunctiva
describe the properties of the conjunctiva
Specialised endothelial venules for regulated migration of lymphoid cells
Diffuse lymphoid populations in all conjunctival zones
Dendritic cells act as APCs
Mucosa associated lymphoid tissue (MALT)
Macrophages, Langerhans cells and mast cells frequent the MALT, neutrophils/eosinophils only there if recruited
Commensal bacteria
describe the properties of the cornea and sclera
‘tough collagen coat’
Avascularity
No lymphatics/lymphoid tissue
Langerhans cells only in peripheral cornea
Downregulated immune environment
what autoimmune conditions can affect the cornea and sclera?
crohn’s, UC, RA, vasculitis
what cells are found in the lacrimal gland?
plasma cells (IgA) and CD8+ T cells (more than conjunctiva)
T cells in small groups around intralobular ducts
what does it mean to have immune privilege?
somewhere that can tolerate the introduction of antigens without eliciting an inflammatory immune response
(the eyes have immune privilege)
what sites in the eye have immune privilege?
Cornea
Anterior Chamber
Lens
Vitreous cavity
Subretinal space
what is sympathetic opthalmia?
Rare, bilateral, granulomatous uveitis due to trauma or surgery to one eye
so damage one eye and blindness spreads to both
what are the primary mediators of sympathetic opthalmia?
T cells
what type of hypersensitivity reaction is acute allergic conjunctivitis?
type I
what type of hypersensitivity reaction is ocular cicatricial pemphigoid?
type II (direct cell killing)
