Week 1 - J - Immunology of the eye and immune privelage - and sympathetic ophthalmia

Question 1

What are the two types of immunity from the immune system?

Answer 1

Innate - non specific first line response

Acquired - specific and has a memory

Question 2

The innate and adaptive immune system work synergistically to tackle immune problems How long does the innate immunity take to react vs the acquired?

Answer 2

Innate immunity is a rapid, immediate response

Acquired immunity gradually takes place over a few days

Question 3

The innate immunity gives a physical barrier for protection eg skin What does the eye lack to give this physical barrier?

Answer 3

It lacks skin over the eye

Question 4

Due to the eye not being protected from pathogens by innate immunity facotrs such as physical barrier and commonesal bacteria How does it make up for this?

Answer 4

Reflex tears and the chemical properties of tears eg lysozymes

Also reducing the size of the eye to prevent infection from entering

Question 5

In the inate system of the eye You have the blink reflex and physical properties of the srufce eg tears, have chemical properties and have the immune cells of the eye WHat are the three layers of the tear film of the eye? (what produces each layer)

Answer 5

Have an oily lipid outer layer - meibum produced from tarsal glands in the eylid

Have an aqueous middle layer containing chemicals

Have a mucin layer - mucous produced by the bulbar conjunctivae goblet cells

Question 6

What is the chemical propery of tears that acts against gram negative and what acts against gram positive?

Answer 6

Lysozyme fights gram negative bacteria and fungi and destroys the cell wall

Lactoferrin and transferrin acts againt gram +ve bacteria

Question 7

What immunoglobulin is secreted in tears?

Answer 7

IgA

Question 8

What are the three main immune cells of the eye?

Answer 8

Neutrophils

Macrophages

Conjunctival mast cells

Question 9

Which of the immune cells helps to trigger the adaptive immune system?

Answer 9

The macrophages

Question 10

The adaptive immune system requires antigen presenting cells with lymphatic drainage to lymph node and a variety of effector cells What is the main antigen presenting cell in the external eye and skin?

Answer 10

The Langerhans cell

Question 11

What layer of skin is the langerhans cell most common in?

Answer 11

Most common in the prickle cell layer - stratum spinosum

Question 12

The langerhan cells are rich in what MHC class?

Answer 12

Righ in MHC Class II - helps activate CD4+

Question 13

What are MHC II cels important in initiating?

Answer 13

They are important in initiating immune response

Question 14

Langerhan cells are abundant at corneo-scleral limbus, less in peripheral cornea, where are they absent?

Answer 14

they are absent in the central 1/3rd of the cornea

Question 15

What is the only part of the eye with lymphatic drainage?

Answer 15

The conjunctiva

Question 16

What layer of the eye is avascular?

Answer 16

The cornea and sclera

Question 17

What is the lacrimal drainage system?

Answer 17

They have diffuse lymphoid tissue and follicles (MALT) which drains into the lacrimal punctum

Question 18

Certain sites of the body are able to tolerate the introduction of antigens without eliciting an inflammatory immune response The eye is one of these sites, what is this known as?

Answer 18

The immune privelage

Question 19

What sites in the eye are immune privileged? (mnemonic CALVS)

Answer 19

The corrnea

Anterior chamber

Lens

Vitreous cavity

Subretinal space

Question 20

Ocular immune privilege mechanisms include: Unique anatomical features of a blood-tissue barrier and a lack of direct lymphatic drainage Ocular microenvironment is rich in immunosuppressive molecules and inhibitory cell surface molecules that influence the reactivity of immune cells Anterior chamber-associated immune deviation (ACAID)

What is the blood tissue barrier of the eye?

Answer 20

The choroid and retina

Question 21

The anterior chamber associated immune deviation has some immunological hallmarks What does it inhibit?

Answer 21

Inhibits the cell mediated immune response (Type IV hypersensitivity)

Question 22

Rare, bilateral, granulomatous uveitis due to trauma (more common) or surgery (less common) to one eye ?

Answer 22

This is known as sympathetic opthalmia

Question 23

How does the sympathetic opthalmia begin?

Answer 23

Starts of as uveitis as the immune system is attacking one eye and then the immune system begins to attack the other eye

Question 24

What is the exciting and sympathetic eye in sympathetic opthalmia?

Answer 24

Exciting eye is the injured eye

Sympathetic eye is the fellow eye

Question 25

How does the trauma to one eye cause the immune system to release T cells to damage both eyes?

Answer 25

Trauma to on eye ends up with the release of antigens in this eye, they travel to the lymph nodes where Tcells are produced and travel in the bloodstream to affect both eyes

Question 26

How does sympathetic opthalmia relate to a disadvantage of the immune privelage of the eye?

Answer 26

Relates to the physical and immunological isolation of the eye from the systemic immune system

Question 27

What parts of the eye has the immune privelage? (recap question) (CALVS)

Answer 27

CALVS

Cornea

Anterior chamber

Lens

Vitreous chamber

Subretinal space

Question 28

An example of type 1 hypersensitivity condition is allergic conjunctivitis How does this immune process work?

Answer 28

There is always more antibody than antigen produced so when exposed originally to the allergen the IgE antibodies bind to Fc receptors on the mast cells

Next time on exposure the IgE is already formed and this causes degranulation of the mast cells releasing eg histamine

Question 29

Autoimmune conditions are usually classified as type II hypersensitivty WHat is an example of a type II which is known as a subtype of mucous membrane pemphigoid?

Answer 29

This would be ocular cicatricial pemphigoid

Question 30

Ocular cicatricial pemphigoid is an autoimmune condition affecting the conjunctivae What can you treat this with?

Answer 30

Can try steroids

Question 31

Type III hypersensitivity - Autoimmune corneal melting

Outer layer of cornea melting; inner layer bulging forward  possible perforation What can perforation cause?

Answer 31

Can massively increase chance of infection as there will be a hole straight to the eye

Question 32

What are side effects of steroid use in the eye?

Answer 32

Can cause glaucoma by damaging the trabecular meshwork leading to a build up of pressure in the eye

Can denature lens fibres leading to cataracts