Immunology Flashcards

1
Q

State four aspects of the innate immune system of the eye

A
  • blink reflex
  • chemical properties
  • immune cells
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2
Q

How does the mucous layer help protect the body?

A

It is anti-adhesive

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3
Q

What chemicals do tears contain that help fight pathogens?

A

Lysozyme, lipids, antimicrobials and immune mediators

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4
Q

Name three immune cells found in the eye

A

Neutrophils, macrophage and mast cells

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5
Q

What are the three key differences between innate and adaptive immune response?

A

Innate - rapid, targets group of pathogens, no memory

Adaptive - gradual, targets specific pathogens, memory

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6
Q

What does the adaptive immune system require?

A

Antigen Presenting Cells
Lymphatic Drainage
Effector Cells

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7
Q

What are the main antigen presenting cell for the external eye?

A

Langerhans Cells

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8
Q

Where are langerhans cells found and what are they rich in?

A

Highly abundant at the corneoscleral limbus rich in MCH class II molecules

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9
Q

Name the only part of the eye with lymphatic drainage

A

Conjunctiva

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10
Q

In the conjunctiva what are the main APC and what are these closely related to?

A

Dendritic cells close association with MALT

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11
Q

What is MALT?

A

Mucosa associated lymphoid tissue - clusters of cells that identify abnormal cells

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12
Q

Name three types of cells that make up MALT

A
  • Macrophage
  • Mast cells
  • Langerhans cells
    Also some commensal bacteria
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13
Q

Do the cornea/sclera have any lymphatic tissue?

A

no

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14
Q

Describe the immunology of the lacrimal gland

A

More IgA and CD8 T cells compared to conjunctiva in addition to small groups of T cells around the intralobar ducts

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15
Q

What mechanism prevents movement of cells in/out of the eye?

A

Blood ocular barrier

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16
Q

What is immune privilege?

A

Certain sites in the body are able to tolerate the introduction of antigens without electing an inflammatory immune response

17
Q

Which parts of the body show immune privilege?

A

Testes
Placenta/foetus
Eyes

18
Q

Specifically which part of the eyes have immune privilege?

A

Cornea, anterior chamber, lens, vitreous cavity, subretinal space

19
Q

Name three mechanisms that allow the eye to have immune privilege

A
  • blood tissue barrier and lack of lymphatic drainage
  • microenvironment of immunosuppressive molecules
  • anterior chamber associated immune deviation
20
Q

What is the anterior chamber associated immune deviation?

A

Peripheral tolerance to ocular antigens - placement of a foreign antigen into the ocular microenvironment can induce a systemic form of tolerance

21
Q

What is the purpose of ACAID?

A

Acts to protect the eye from the collateral damage of an immune response to infection

22
Q

How does does ACAID protect the eye from collateral damage?

A

Primes T and B cells to produce non-complement fixing antibodies
Inhibits delayed type hypersensitivity

23
Q

Describe the immunological ignorance of corneal cells

A

Reduced expression of MHC class I molecules and no expression of MHC class II or blood/lymphatic vessels

24
Q

Name a rare autoimmune reaction to ocular antigens

A

Sympathetic Ophthalmia

25
Describe sympathetic ophthalmia
Uveitis due to trauma or surgery resulting in bilateral granulomatous due to an initial wave of CD4 T cells followed by a later wave of CD8 T cells. Immune cells are sent to both eyes post penetration to attack the 'antigen'
26
What are the injured and other eye known as in sympathetic ophthalmia?
Injured - exciting | Fellow - sympathising
27
Name six autoimmune conditions of the eye
- autoimmune uveoretinitis - dalen-fuchs nodule - keratoconjunctivitis - lens induced uveitis - retina autoantibodies - sympathetic ophthalmia
28
What are the key risks of a defective immune system?
Recurrent infections/cancer
29
What are the key risks of a hyperactive immune system?
Responds to harmless substances and self, rejects transplants and may cause allergies
30
Describe and give an example of a type 1 hypersensitivity reaction
IgE, mast cells and vasoactive mediators | E.g. acute allergic conjunctivitis
31
What is the word used to describe conjunctival oedema?
Chemosis
32
Describe and give an example of a type 2 hypersensitivity reaction
Direct cell killing with macrophage and complement | E.g. Ocular creatricial pemphigoid
33
How is ocular pemphigoid treated?
Steroids
34
What are the two ocular side effects of steroids?
Cataracts and glaucoma
35
Describe and give an example of a type 3 hypersensitivity reaction
Immune complex mediated involves accumulation of antigens bound to antibodies that fix complement E.g. Autoimmune corneal melting
36
Describe autoimmune corneal melting
Outer layer of cornea melts while the inner layer bulges forward which can cause perforation
37
Describe and give an example of a type 4 hypersensitivity reaction
Delayed type, T helper cells are activated by intracellular pathogens leading to clonal expansion and on re-exposure macrophage attack leading to an exaggerated response E.g. transplant rejection
38
What must be prevented in order for a cornea transplant not to be rejected?
Vascularisation
39
How does immune privilege play a role in transplant acceptance?
- reduces MCH expression - avascular cornea - cornea deficient of langerhans - immunosuppressive molecules - ACAID