immunology of the eye Flashcards
what is innate immunity?
-first line response: physical barrier, commensal bacteria, chemical agents and various cell types
what is adaptive immunity?
-Aquired, specific, learned immunity that usually involves B and T cells
what is the physical barrier in the eyes?
- tear film
- eyelid (blinking)
- mucus membrane and cornea are coated so that it is a non sticky surface
how do tears act as a physical barrier?
- flush away bacteria
- have a mucous layer which works as an anti adhesive
what does each layer of the tear film do?
lipid layer- stops it evaporating
aqueous layer- tears
mucin layer- allows tears to sit to cornea
Go over this!
what chemical components do the tears have?
what are the antigen presenting cells in the eye?
Langerhan cells
is there lymphatic drainage in the eye?
yes in the eye lids and the eyelid component of the conjunctiva
where are most of the T and B cells found in the eye?
in the conjunctiva
where are most of the langerhan cells found?
in the cornel-scleral limbus
which is the conjunctiva the only part of the eye that can drain lymph?
as it contains specialised endothelial venules for regulated migration of lymphoid cells
how do the cornea and sclera play a part in the immune system?
- they are a tough collagen coat
- have some antigen-presenting cells (but not as much as anywhere else in the body)
- downgraded immune enviroment
- avascular (cant get chemotaxis)
what sites in the eye are immune privileged?
- cornea (not as much, can still be rejected)
- anterior chamber
- lens
- vitreus cavity
- subretinal space
what does immune privileged mean?
-there is a limit to a structures immune response so there usually is not an inflammatory immune response
what is the problem with immune privilege in the eye?
-you an have trauma in one eye and then your immune system might attack the other eye as well (sympathetic opthalmia)
what is the definition of type 1 hypersensitivty
- involves IgE and degranulation of mast cells
- immediate hypersensitivty
what type of reaction is acute allergic conjunctivitis?
type 1 hypersensitivty reaction
describe type II hypersensitivty reaction
- direct cell killing
- antibody-mediated cytotoxicity
what type of reaction is ocular cicatricial pemphigoid?
type 2 hypersensitivity??
describe type III hypersensitivty reaction
- immune complex mediated
- antigen causes production of antibodies causing complexes
what type of hypersensitivty reaction is corneal melting
type III
describe type IV hypersensitivity reaction
- delayed reaction
- initially antigen presenting cells present antigen to T cells, T cells create a memory for it so when they are exposed to the same antigen next time they will have a reaction
what reaction does a corneal graft rejection involve?
type IV hypersensitivity
who is more likely to have type I and type IV hypersensitivty?
people with asthma, eczema
what is used to counteract inflammation in the eye?
steroids
what are SE of steroids ?
- cataracts
- steroid induced glaucoma
