Immunology of the Eye Flashcards
How has the eye adapted for innate immunity?
Blinking
Reducing exposure
Reducing size
Chemical barriers
What are the physical barriers tears produce?
Flushing
Anti-adhesive mucous layer
What are the chemicals in tears and what do they protect against?
Lyzozyme - grami -ve and fungi
Lactoferrin and transferrin - gram +ve
Tear lipids - antibacterial to cell membranes
Secretory IgA - prevents attachment
What are the cellular components in tears?
Neutrophils
Conjunctival Mast Cells
Macrophages
How are neutrophils attracted and what is their action
Chemotaxis
Scavengers release free radicals
What is the purpose of macrophages?
Phagocytosis
Trigger adaptive immunity
What is the purpose of conjunctival mast cells?
vasoactive mediators
What part(s) of eye have lymphatic drainage?
Conjuntiva only
How have the conjuctiva gained acquired immunity?
Dendritic cells as antigen presenting cells
Lymphoid associated mucosa
Commensal bacteria
Describe how the cornea and sclera have down regulated immune environment
Avascular
No lymphoid tissue
lack of antigen presenting cells
Describe how the vitreous, choroid and retina have a downregulated immune environment
Blood-ocular barrier
lack of antigen presenting cells
What is a Type 1 hypersensitivity reaction? How is it mediated?
Immediate
IgE mediated
Histamine, leukotrine, cytokine release (vasoavtive mediators
Give an example of Type 1 Hypersensitivity reaction in the eye
Hayfever
Acute allergic conjunctivitis
What is Type 2 hypersensitivity reaction? How is it mediated?
Direct killing (antibody mediated cytotoxicity)
Macrophages/natural killer cells
Complement (membrane attack complex)
Give an example of ocular type 2 hypersensitivity
Ocular cicatricial pemphigoid
What is type 3 hypersensitivity? How is it mediated?
Immune complex mediated
Antibody-antigen complexes form
Fixed by complement
Cleared from system
Give an example of ocular type 3 hypersensitivity
Autoimmune corneal melting
What is type 4 hypersensitivity? How is it mediated?
Delayed response
T helper cells activated by intracellular pathogens
Clonal expansion
Macrophages attracted on re-exposure
Give an example of ocular type 4 hypersensitivity
Corneal graft rejection
