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OD2 (S1&2) > MIIM - Ocular Defences: The Immune System I - Week 4 > Flashcards

MIIM - Ocular Defences: The Immune System I - Week 4 Flashcards

1
Q

What are the three main mechanisms of action for the innate immune system via protein action?

A

Pathogen lysis
Opsonisation
Phagocyte chemotaxis
All these occur via the complement cascade

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2
Q

What are the three main mechanisms of action for the innate immune system via cell action?

A

Phagocytosis
Killing of infected cells

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3
Q

Name 2 ways pathogens can evade the innate immune system.

A

Replicating very quickly
Viruses that can hide in cells and replicate

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4
Q

Name three defences against pathogens that can be found on the ocular surface.

A

Lids and tears to wash away the surface
Complement proteins in the tears and conjunctival tissue to lyse pathogens
Macrophage and neutrophils enter via the blood to phagocytose survivors

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5
Q

What happens to phagocyte activity on the ocular surface when the lids are closed?

A

It increases, they enter via blood vessels

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6
Q

Innate defences in the eye have a heavy reliance on physical and soluble mediators. Why is this the case?

A

Cellular response to pathogens impairs vision and inflammatory responses can cause significant damage.

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7
Q

What are the effector cells of the adaptive immune system?

A

Lymphocytes

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8
Q

What kind of receptors do lymphocytes have?

A

Highly diverse antigens

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9
Q

Describe the two kinds of lymphocytes, what they are derived from, and what sub-category of immune system they belong to.

A

B-lymphocyte - bursa derived. They belong to humoral immunity.
T-lymphocyte - thymus derived. They belong to cell mediated immunity.

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10
Q

What do B-lymphocytes do?

A

Produce antibodies in response to a bound antigen, for which they have a specific receptor to.

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11
Q

Name the two types of T-lymphocytes. What cell activates these two, and what immune system does it belong to?

A

T helper cell
Cytotoxic T cell
They are activated when a T cell receptor binds to an antigen displayed by dendritic cells (also known as antigen presenting cells) and induces their activation. It belongs to the innate immune system, and bridges the two immune systems together.

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12
Q

Do both B- and T-lymphocytes have highly diverse receptors for antigens?

A

Yes both

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13
Q

Do B- and T-lymphocytes have receptors to many different kinds of antigens on one cell, or specific to one kind of antigen?

A

Specific to one kind of antigen. Thus it can only respond to a limited number of similar antigen (as well as the antigen itself)

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14
Q

By what process are B- and T-lymphocyte receptors generated and when (and where)?

A

Random somatic gene rearrangement, during differentiation in the primary lymphoid tissue.

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15
Q

Consider a B- or T-lymphocyte that has matured and has a receptor to a particular antigen ready. What are the conditions for it to be able to leave the primary lymphoid tissue?

A

Only those cells which express receptors for non-self antigens can leave.

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16
Q

Name three locations in which lymphocytes develop/

A

Foetal liver
Bone marrow
Thymus

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17
Q

Name three locations in which lymphocytes will interact with foreign antigens should they be present.

A

Spleen
Lymph nodes
MALT
These are secondary lymphoid organs

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18
Q

Once a lymphocyte has interacted with an antigen, what happens to it, and where does it go?

A

It turns from a naïve lymphocyte into an effector lymphocyte, allowing it to rejoin circulation and also enter tissue.

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19
Q

Do activated lymphocytes enter the spleen?

A

No

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20
Q

Name three eye associated lymphoid tissue.

A

Lacrimal gland
Conjunctiva
Lacrimal drainage system

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21
Q

Given the central cornea is avascular, are there any immune cells present on the cornea, and if so, where and what.

A

Dendritic cells are found in the peripheral corneal epithelium

22
Q

Does the intraocular compartment have any lymphatic drainage?

A

No

23
Q

If antigens or dendritic cells may leave the intraocular compartment, where may they end up and how?

A

To the spleen, via the trabecular meshwork

24
Q

Define anterior chamber associated immune deviation.

A

Immune responses in the intraocular environment are suppressed.

25
Q

Describe the structure of an antibody, including the number of chains, and what bonds hold them together.

A

It is a Y shaped polypeptide. It is composed of 4 peptides, two identical heavy and two identical light chains.
The heavy chains form the skeleton of the Y shapes, and are held at the kink by two disulphide bonds.
Two light chains hang off the arms, one for each, and are held on by a single disulphide bond, which can be found on the end of the peptide closer to the kink.
The base of the Y can attach to immune cells.
The ends of each of the Y arms have receptors specific to a particular antigen.

26
Q

Describe what is meant by the constant and variable regions of an antibody (and their symbol as well).
Describe where on an antibody these regions are.

A

Constant region - Fc - can take one of 5 forms. Forms the base of the Y shape.
Variable region - Fab - can take on one of an almost infinite variety of forms. Forms each arm of the Y shape.

27
Q

How many receptors are possible for antibodies in humans?

A

10^11

28
Q

Name the 5 classes of the constant region of antibodies.

A

IgA
IgD
IgE
IgG
IgM

29
Q

Explain how antibodies can act as an opsonin.

A

The Fc region binds to phagocytes by C’ molecules to C’ receptors, or by its Fc region to Fc receptors, thus acting as an opsonin.

30
Q

Which antibody (of the 5) is responsible for preventing pathogen binding at mucosal surfaces?

A

IgA

31
Q

Which antibodies (of the 5) are responsible for neutralising the action of toxins?

A

IgA, IgG, and IgM

32
Q

Which antibody (of the 5) can act as an opsonin, and via what receptor?

A

IgG via Fc receptors which it binds directly to

33
Q

What two antibodies c(of the 5) can trigger the complement cascade?

A

IgG and IgM

34
Q

What two antibodies (of the 5) can induce the release of cytotoxic products, and from which cells (3)?

A

IgG - macrophages and NK cells
IgE - eosinophils

35
Q

When do B cells proliferate?

A

Only when they bind to an antigen, and then secrete antibodies to this antigen.

36
Q

How many generations of B-cells can be generated once a B cell binds an antigen, and how long does that take?

A

8-10 generations in 5 days.

37
Q

What two cells are produced when a B cell proliferates? What are their proportions like?

A

A large number of plasma B cells are produced, and these secrete antibodies.
Memory cells specific to that antigen persist, and these serve as a quick response in subsequent infections.

38
Q

Are memory cells a feature of B-cells only or do T-cells feature them too?

A

Both of them have this response.

39
Q

What two antibodies can act as opsonins?

A

IgG and IgM

40
Q

What two locations are IgG antibodies found?

A

Blood
Tissue

41
Q

What two locations are IgA antibodies found?

A

Blood
Secretions

42
Q

Where are IgM antibodies found (1)?

A

Blood

43
Q

In what two locations are IgE antibodies found?

A

Basophils
Mast cells

44
Q

Order the antibodies in order of serum concentration level.

A

IgG, IgA, IgM, IgE
or GAME
(no idea about IgD)

45
Q

Order the antibodies in order of their antimicrobial activity.

A

IgG, IgA, IgM, IgE
or GAME
(no idea about IgD)

46
Q

What is IgE thought to be effective against?

A

Parasites

47
Q

What two antibodies play a role in allergic activity?

A

IgE mostly
IgG (not as much)

48
Q

Which antibody can cross the placenta?

A

IgA

49
Q

Order the antibodies in order of tear concentration level.

A

IgA, IgG, IgE
No IgM present
(also AGE)

50
Q

Of the antibodies present in tears, which increase when there is a baterial infection present, and which dont?

A

IgG - slight increase
IgA - increase
IgM - slight increase
IgE - constant

51
Q

Of the antibodies present in tears, which increase when there is an allergic reaction, and which dont?

A

IgG - slight increase
IgA - normal
IgM - absent
IgE - slight increase

OD2 (S1&2) (174 decks)

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