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1. Opthalmology > Immunology > Flashcards

Immunology Flashcards

1
Q

What are the solutions to the fact that the eye has no physical barrier?

A

blink reflec
physical and chemical properties
limit exposure/size

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2
Q

What comprises the blink reflex?

A

tears - physical protection

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3
Q

What is the tear film made up of?

A

outer lipid layer
aqueous layer - nourishes the eye
mucin layer - sticks everything to the eye and traps pathogens so they cannot go into the eye

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4
Q

What are the chemicals in tears meant to do?

A

destroy bacteria

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5
Q

What immune cells does the eye contain?

A

neutrophils
macrophages
conjunctival mast cells

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6
Q

What is the priniciple antigen presenting cell of the external eye?

A

Langerhan cells - rich in class 2 MHC molecules

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7
Q

What is the adaptive immune system of the eye?

A

antigen presenting cells eg - dendritic cells, B cells and macrophages
lymphatic drainage to the lymph nodes to start an immune reaction
effector cells - CD4 T cells, CD8 T cells, B cells

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8
Q

Where are Langerhan cells usually found in the eye?

A

abundant at the limbus
less in the peripheral cornea
absent from central 1/3rd

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9
Q

What is special about the conjunctiva?

A

only area in the eye with lymphatic drainage - contains specialised endothelial venules for regulated migration of lymphoid cells
contains MALT

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10
Q

What is MALT?

A

mucosal associated lymphoid tissue - clusters of immune cells

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11
Q

Describe the cornea and scleras immune system?

A

down regulated immune environment
tough collagen coat
no lymphatics or blood supply
lack of APCs

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12
Q

Describe the immune situation of the lacrimal gland?

A

more plasma cells (IgA) and CD8 tcells than conjunctiva

T cells stay in small groups in the intralobular ducts

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13
Q

Describe the immune situation of the lacrimal drainage system?

A

MALT tissue containing diffuse lymphoid tissue and follicles

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14
Q

What is the immune situation of the vitreous, choroid and retina?

A

downregulated immune environment
lack of APCs
blood-ocular barrier limits the spread between eye and blood

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15
Q

What parts of the eye have a downregulated immune environment?

A 
vitrious 
choroid
retina
cornea
sclera
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16
Q

What is immune privilege?

A

the ability of the eye to tolerate invading pathogens without elicting an inflammatory response

17
Q

What sites in the eye have immune privilege?

A 
cornea
anterior chamber
lens
vitrous cavity
subretinal space
18
Q

What is immune privilege brought about by?

A

anterior chamber associated immune deviation (ACAID)

19
Q

What is ACAID?

A

a tolerance can form to the pathogen because the active mechanisms down regulate the normal response

20
Q

What are the immunological hallmarks of ACAID?

A

generation of primed CD4 T cells and B cells that produce non complement fixing antibodies
inhibition of delayed-type hypersensitivity and B cells that secrete complement fixing antibodies

21
Q

What are the other mechanisms of immune privilege?

A

ocular microenvironment is rich in immunosuppressive molecules and inhibitory cell surface molecules
there are special antimicrobial features of the blood brain barrier
lack of lymphocytic drainage

22
Q

What is sympathetic ophthalmia?

A

a rare bilateral granulomatous uveitis where one eye is affected initially, then the other

  • disadvantage to immune privilege
  • can leave person completely blind
23
Q

What causes sympathetic opthalmia?

A

an autoimmune reaction to ocular antigens

24
Q

What is the pathophysiology behing sympathetic opthalmia?

A

trauma to one eye results in the release of squestered intraocular protein antigens which are carried to lymph nodes to activate T cells
effector T cells return via blood stream to BOTH eyes and so both eyes develop the inflammatory reponse

25
Q

What type of hypersensitivity reaction is acute allergic conjunctivits?

A

Type 1

- presents with chemosis and an itchy, watery, puffy eye

26
Q

What type of hypersensitivity reaction is ocular cicatrical pemphigoid?

A

Type 2

27
Q

What is ocular cicatrical pemphigoid?

A

blistering and scarring of the conjunctiva - destruction of the eye architecture
treated with steroids

28
Q

What type of hypersensitivity reaction is autoimmune cornea melting?

A

Type 3

29
Q

What is autoimmune cornea melting?

A

outer layer of cornea melts so the inner layer buldges forward
common in those with corneal grafts - due to lack of APCs
treated with high dose steroids

30
Q

What type of hypersensitivity reaction is corneal graft rejection?

A

Type 4

- wont be rejected until there is vascularisation

1. Opthalmology (21 decks)

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