Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Opthamology > Immunology > Flashcards

Immunology Flashcards

1
Q

via what 2 methods can the immune system eliminate harmful micororganisms?

A

distinguish self from non self

identify danger signals (e.g inflammation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is innate immunity?

A

first line

physical barrier, commensal bacteria, chemical agents

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is adaptive immunity?

A 
acquired
specific
learned
transferable
tolerance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

when do the innate and adaptive immune system kick in after pathogen exposure?

A

immediate innate response = 0-4 hrs (complement, mast cells, macrophages, inflammation)
early innate response = 4-96 hrs (recruitement/activation of phagocytes, inflammation)
late - adaptive response = >96 hrs (immune response)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

how do innate and adaptive immunity differ in terms of targeted pathogens and memory?

A

innate targets groups of pathogens and responds to only a limited number of microbial structures
adaptive targets specific pathogens and can respond to a huge array of different microbial structures
only adaptive has memory

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

are innate and adaptive immunity distinct?

A

no

they work together (synergistic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

describe innate imunity in the eye

A

no physical barrier (no skin)
not many commensal bacteria
does have chemical agents
does have protective cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

how are the limitations of innate immunity in the eye (lack of physical barrier etc) overcome?

A

blink reflex
limit exposure/size
physical and chemical properties of eye surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what physical properties of the eye provide innate immunity?

A

tears
flushing of the eye
mucous layer = anti-adhesive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what chemical properties of the eye provide innate immunity?

A 
tears (chemicals in tears)
lysozyme (destroy fungal and gram -ve cell wall)
lactoferrin and transferrin (gram +ve)
tear lipids (antibacterial to cell membrane/bacterial products)
angiogenin (antimicrobial effect)
secretory IgA (prevents attachment)
complement
IL-6, IL-8, MIP (recruit leucocytes)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what immune cells in the eye provide innate immunity?

A

tears (immune cells in tears)
neutrophils (attracted by chemotaxis and release free radicals and enzymes)
macrophages (phagocytosis of damaged cells and help trigger adaptive immune system)
conjunctival mast cells (vasoactive mediators)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

adaptive immunity in the eye requires what 3 things?

A

antigen presenting cells (dendritic, B cells, macrophages)
lymphatic drainage
variety of effector cells (CD4, CD8, B cells)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the principle antigen presenting cell in the external eye and describe its features

A 
Langerhans cells
rich in class II MHC molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

where are Langerhans cells mainly found in the eye?

A

abundant at corneo-scleral limbus
less in peripheral cornea
absent in central 1/3rd of cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

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

A

conjucntiva

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the conjunctiva?

A

specialised endothelial venules for regulated migration of lymphoid cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is present in the conjucntiva?

A

diffuse lymphoid populations (CD4 and CD8 T cells, IgA secreting plasma cells)
dendritic cells
mucosa associated lymphoid tissue (MALT)
commensal bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is present in the MALT in the conjunctiva?

A

macrophages, Langerhans and mast cells frequent the MALT

neutrophils/eosinophils only there if recruited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the cornea and sclera?

A

tough collagen coat of the eye

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is present within the cornea and sclera?

A 
avascular
no lymphatics or lymphoid tissue
relative lack of APCs
Langerhans only in peripheral cornea
downregulated immune environment
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

describe the components of the lacrimal gland

A

more plasma cells (IgA) and CD8 cells compared to conjunctiva
T cells in small groups around intralobar ducts
resting lymphoid cells very rarely observed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is present in the lacrimal drainage system?

A

diffuse lymphoid tissue and follicles in mucosa (MALT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

describe the features of the vitreous, choroid and retina

A

blood -ocular barrier
relative lack of APCs
downregulated immune environment

24
Q

describe the concept of immune privilege

A

certain sites of the human body have the ability to tolerate the introduction of antigens without eliciting an inflammatory response

25
Q

name 4 areas of the body which display immune privilege

A

brain/CNS
testes
placenta/foetus
eyes

26
Q

what sites in the eye display immune privilege (5)?

A 
cornea
anterior chamber
lens
vitreous cavity
subretinal space
27
Q

name 3 immune privilege mechanisms in the eye

A

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 deactivation (ACAID)

28
Q

what is ACAID and what does it do?

A

“anterior chamber associated immune deviation”
systemic form of tolerance to foreign antigen (peripheral tolerance to ocular antigens)
active mechanisms downregulate the immune response within the eye and protect the eye and visual axis from the collateral damage of an immune response to infection by suppressing a future potentially damaging response to infection

29
Q

what are the immunological hallmarks of ACAID?

A

generation of primed CD4 T and B cells the produce non-complement-fixing antibodies
inhibition of delayed type hypersensitivity (CD4 Th1) and B cells that secrete complement-fixing antibodies (inhibition of a cell mediated response)

30
Q

what are the 3 principles which establish ocular immune privilege?

A

separation (immunological ignorance)
inhibition (development of an intraocular immunosuppressive microenvironment)
regulation (peripheral tolerance to ocular antigens)

31
Q

how does separation achieve immune privilege?

A 
corneal cells have reduced expression of MHC class I molecules and do not express MHC class II molecules
normal cornea lacks blood and lymphatic vessels
32
Q

how does inhibition establish immune privilege?

A

local factors within the eye inhibit components of the immune response to reinforce the protection provided by immune privilege

33
Q

how does regulation achieve immune privilege?

A

ACAID

34
Q

what is sympathetic opthalmia?

A

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

35
Q

what causes sympathetic opthalmia?

A

secondary to development of an autoimmune reaction to ocular antigens: exposed during the traumatic or surgical event
related to the physical and immune isolation of the eye from the systemic immune system (disadvantage of immune privilege)
this means that immune response occurs at elevated rates

36
Q

what cells are involved in sympathetic opthalmia?

A

primary mediator = T cells
initial wave = CD4 T cells
later wave = CD8 T cells

37
Q

how does each eye differ in sympathetic opthalmia?

A

injured eye = exciting eye
fellow eye = sympathising eye
clinically both eyes appear the same, can only tell which one is exciting eye by history

38
Q

how does sympathetic opthalmia occur?

A

trauma to one eye results in release of sequestered intraocular protein antigens
released intraocular antigen is carried to lymph node and activated T cells
effector T cells return via bloodstream and encounters antigen in both eyes

39
Q

name 6 autoimmune diseases of the eye

A

autoimmune uveoretinitis (inflammation of uvea and retina)
Dalen-Fuchs nodule (epithelial clusters in retinal layers)
keratoconjunctivitis sicca (dry eyes)
lens induced uveitis (reaction due to release of lens products)
retina autoantibodies (common inretinopathy associated with cancer/infection/degenerative disease)
sympathetic opthalmia (bilateral granulomatous uveitis)

40
Q

what is the role of mast cells in allergic reactions (type 1)?

A

express receptors for Fc region of IgE antibody on their surface
on encounter with allergen, B cells produce antigen-specific IgE antibody and allergen is cleared

41
Q

what happens after allergen in cleared in a type 1 response?

A

allergen is cleared
residual IgE antibodies bind to circulating mast cells via Fc receptors
no great consequence until allergen is re-encountered

42
Q

what happens when the allergen is re-encountered in type 1 response?

A

allergen binds to IgE coated mast cells and disrupts cell membrane
release of vasoactive mediators (histamine, tryptase etc)
also increased cytokines and leukotriene transcription

43
Q

give an example of a type 1 reaction in the eye

A

acute allergic conjunctivitis (chemosis)

44
Q

via what 2 methods are cells killed in a type 2 response?

A

macrophages/natural killer (NK) cells

complement (membrane attack complex)

45
Q

give an example of a type 2 response in the eye

A

ocular cicatricial pemphigoid

- causes blistering and scarring of the conjunctiva

46
Q

how may ocular cicatricial pemphigoid be managed?

A

steroids

- dampens down immune response

47
Q

what happens in the early stage of type 3 response?

A

early stage = little antibody and lots of antigen, small immune complexes form that do not fix complement and are not cleared from circulation

48
Q

what happens in the intermediate stage of type 3 response?

A

comparable amounts of antibody and antigen

large immune complexes are formed which fix complement and are cleared form circulation

49
Q

what happens in late stage of type 3 response?

A

large amounts of antibody and little antigen

medium-sized immune complexes form that fix complement and are cleared from circulation

50
Q

give an example of type 3 response in the eye?

A

autoimmune corneal melting

51
Q

what cells are involved in type 4 response?

A

T helper cells activated by intracellular pathogens
clonal expansion
when re-exposed, macrophages attracted
leads to exaggerated immune response

52
Q

what are the 2 phases in type 4 hypersensitivity?

A

sensitisation phase

effector phase

53
Q

give an example of type 4 hypersensitivity in the eye

A

corneal graft rejection

54
Q

what factors may help in maintaining immune privilege in a corneal transplant?

A

reduced/impaired expression of MHC I and II in corneal cells
cornea lacks blood and lymph vessels
central cornea is deficient in Langerhans cells
secretion of molecules with immunosuppressive properties
expression of surface molecules that inhibit immune effectors
ACAID in recipients

55
Q

name 2 possible ocular side effects of steroids?

A

cataracts

steroid induced glaucoma

Opthamology (18 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions