immunology of the eye

Question 1

what is innate immunity?

Answer 1

-first line response: physical barrier, commensal bacteria, chemical agents and various cell types

Question 2

what is adaptive immunity?

Answer 2

-Aquired, specific, learned immunity that usually involves B and T cells

Question 3

what is the physical barrier in the eyes?

Answer 3

• tear film
• eyelid (blinking)
• mucus membrane and cornea are coated so that it is a non sticky surface

Question 4

how do tears act as a physical barrier?

Answer 4

• flush away bacteria

- have a mucous layer which works as an anti adhesive

Question 5

what does each layer of the tear film do?

Answer 5

lipid layer- stops it evaporating
aqueous layer- tears
mucin layer- allows tears to sit to cornea

Go over this!

Question 6

what chemical components do the tears have?

Answer 6

Question 7

what are the antigen presenting cells in the eye?

Answer 7

Langerhan cells

Question 8

is there lymphatic drainage in the eye?

Answer 8

yes in the eye lids and the eyelid component of the conjunctiva

Question 9

where are most of the T and B cells found in the eye?

Answer 9

in the conjunctiva

Question 10

where are most of the langerhan cells found?

Answer 10

in the cornel-scleral limbus

Question 11

which is the conjunctiva the only part of the eye that can drain lymph?

Answer 11

as it contains specialised endothelial venules for regulated migration of lymphoid cells

Question 12

how do the cornea and sclera play a part in the immune system?

Answer 12

• 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)

Question 13

what sites in the eye are immune privileged?

Answer 13

• cornea (not as much, can still be rejected)
• anterior chamber
• lens
• vitreus cavity
• subretinal space

Question 14

what does immune privileged mean?

Answer 14

-there is a limit to a structures immune response so there usually is not an inflammatory immune response

Question 15

what is the problem with immune privilege in the eye?

Answer 15

-you an have trauma in one eye and then your immune system might attack the other eye as well (sympathetic opthalmia)

Question 16

what is the definition of type 1 hypersensitivty

Answer 16

• involves IgE and degranulation of mast cells

- immediate hypersensitivty

Question 17

what type of reaction is acute allergic conjunctivitis?

Answer 17

type 1 hypersensitivty reaction

Question 18

describe type II hypersensitivty reaction

Answer 18

• direct cell killing

- antibody-mediated cytotoxicity

Question 19

what type of reaction is ocular cicatricial pemphigoid?

Answer 19

type 2 hypersensitivity??

Question 20

describe type III hypersensitivty reaction

Answer 20

• immune complex mediated

- antigen causes production of antibodies causing complexes

Question 21

what type of hypersensitivty reaction is corneal melting

Answer 21

type III

Question 22

describe type IV hypersensitivity reaction

Answer 22

• 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

Question 23

what reaction does a corneal graft rejection involve?

Answer 23

type IV hypersensitivity

Question 24

who is more likely to have type I and type IV hypersensitivty?

Answer 24

people with asthma, eczema

Question 25

what is used to counteract inflammation in the eye?

Answer 25

steroids

Question 26

what are SE of steroids ?

Answer 26

• cataracts

- steroid induced glaucoma