Immunology Flashcards
Describe innate immunity
First line response - fast
Includes physical barriers, commensals, chemical agents and cells
Describe adaptive immunity
Acquired immunity - learned
Slower response
Specific
List components of the innate immune system of the eye
Blink reflex
Flushing of the eye
Chemical defences - in tears
Some immune cells are present
What chemical defences are found in tears
Lysozyme Lacto and transferrin Tear lipids Angiogenin Secretory IgA Complement Interleukins
Which immune cells are found in the eye
Neutrophils
Macrophages
Conjunctival mast cells
How do Langerhans cells work in the eye
Main antigen presenting cells for external eye Have lots of MHC class 2 molecules Abundant in the corneal/scleral area
What is the only part of the eye with lymphatic drainage
the conjunctiva
Describe the immune defences of the conjunctiva
Has special venules for migration of lymphoid cells Lymphocyte populations present Dendritic cells work as APC's MALT Commensal bacteria
Describe the immune defences of the cornea and sclera
Avascular and no lymphoid tissue
Relative lack of APCs Langerhans cells only present in peripheral cornea
It is a downregulated immune environment
Describe the immune defences of the lacrimal system
Glands: has more plasma cells and CD8 T cells
Drainage system: has lymphoid tissue (MALT)
Describe the immune defences of the vitreous, choroid retina
Blood ocular barrier - created by tight junctions
Relative lack of APCs
Downregulated immune environment
What are immune privilege sites
Places in the body where antigen introduction is tolerated and doesn’t elicit the inflammatory response
Which sites in the body have immune privilege
Brain
Testes
Placenta/foetus
EYES - cornea, anterior chamber, lens, vitreous cavity
What is ACAID
Anterior chamber associated immune deviation
Introducing a foreign antigen into the eye can induce a form of tolerance
It protects the eye from damage from an immune response by suppressing it
What are the hallmarks of ACAID
Generation of primed CD4 T cells and B cells
Inhibition of delayed-type hypersensitivity
How is ocular immune privilege established
Separation (immune ignorance) - cornea lacks blood and lymph vessels and decreased MHC expression
Inhibitions - local factors supress the immune response
Regulation (tolerance) - ACAID
What can occur immunologically if there is trauma to the eye
Can lead to an exaggerated immune response as it disrupts the carefully balanced system
What is sympathetic ophthalmia
Rare, bilateral, granulomatous uveitis due to trauma or surgery
Injury of one eye leads to inflammation in both
Elevated immune response may be cause - T cells are the main mediators
In sympathetic ophthalmia what is the exciting eye
The one that sustained the injury
The other eye is called the sympathising eye
List some hazards of the immune system
Recurrent infections Inadvertent injury to normal host tissues Allergy Hypersensitivity reactions Autoimmune disease Cancer Transplant/graft rejection
List some ocular autoimmune diseases
Autoimmune uveoretinitis - inflamed uvea and retina
Keratoconjunctivitis sicca (‘dry eyes’)
Lens-induced uveitis
Sympathetic ophthalmia
Give an example of a type 1 hypersensitivity reaction in the eye
Acute allergic conjunctivitis
Give an example of a type 2 hypersensitivity reaction in the eye
Ocular cicatricial pemphigoid
Describe the presentation of acute allergic conjunctivitis
Red, puffy and swollen eye
Very inflamed
Chemosis= classic sign
Itchy watery eye with jelly-like appearance
Describe the presentation of ocular cicatricial pemphigoid
Lid is held open
Blisters form on surface of the eye
Can lead to scarring - destroys eye structure
Cornea becomes hazy
How do you treat ocular cicatricial pemphigoid
Steroids
Give an example of a type 3 hypersensitivity reaction in the eye
Autoimmune corneal melting
treat with steroids
Give an example of a type 4 hypersensitivity reaction in the eye
Corneal graft rejection
Not common
Can occur when tissue becomes vascularised
What side effects of steroids can affect the eye
Can lead to cataract
Steroid-induced glaucoma
