ToB - Immunity Flashcards

0
Q

How do epithelia respond to pathogen attack?

A

1) . They are activated upon attack.
2) . Produce cytokines (cause some cells behaviour to alter) then chemokines (attract other cells and allow leakiness) = fluid migration occurs.
3) . Opsonisation occurs (complement in blood stream)
4) . Phagocytosis
5) . Interaction of macrophage etc. with T helper cells.

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1
Q

What is the function of the epithelia in immunity?

A

Form the first barrier of the innate immune system to pathogens.

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2
Q

What can epithelia produce in terms of immune response?

A

1) . Cytokines - proteins that act as chemical messengers to alter the behaviour of a cell.
2) . Chemokines - proteins that attract other cells and cause them to leak.
3) . Natural antibiotics - cathelicidens, defensins
4) . MAY PRODUCE - mucins, acid

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3
Q

What do inflammatory mediators do and what does this result in?

A

They promote vascular permeability
= leakage of antibodies and complement
= movement of macrophages, neutrophils and lymphocytes into tissues from blood stream.

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4
Q

What are the phagocytosis performing cell components of the innate immune system and what do they do?

A

Neutrophil

  • specialised for anaerobic conditions (as this prevails in damaged tissue)
  • aided by receptors for bacterial constituent so can bind to bacterium and as a result phagocytose better
  • contain granules of NADPH oxidase (oxidative burst) and lysozymes (phagocytosis) but once these run out, more cannot be synthesised

Monocyte/macrophage

  • also act as antigen presenting cells
  • aided by opsonisation
  • release cytokines that activate the T lymphocytes
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5
Q

What are the cellular components of the innate immune system that perform allergic reactions, and what is their function?

A

Eosinophils - antiparasite
Basophils - protect mucosal surfaces
Mast cells - protect mucosal surfaces

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6
Q

What part of the immune system are natural killer cells part of, how are they activated and what is their function?

A

Part of the innate immune system.
Activated by cytokines released by macrophages (IL-12) and a chemical (IFNalpha/beta) released upon viral infection.
Induce apoptosis in a virus infected or cancerous cell.

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7
Q

What is opsonisation?

A

The bacteria is coated with complement or antibodies.
Complement receptors are on phagocytes = mediate engulfment after binding.
Granules can now fuse and kill the pathogen.

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8
Q

What are the humoral components of the innate immune system and their function?

A

Transferrin/lactoferrin - deprive bacteria of iron

Interferon - activate NKCs, inhibit viral replication

Lysozyme - breaks down cell wall of some gram positive bacteria

Fibronectin - opsonisation

Complement - kill microbe, aid in phagocytosis

TNF-alpha - inhibit viral replication, activates phagocytosis

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9
Q

What does complement 3B do?

A

Binds to bacteria covalently and opsonises it.

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10
Q

How can complement components kill a bacterium?

A

1) . C5-9 form a complex which binds to the bacteria membrane.
2) . C8 binds and inserts into membrane
3) . C9 binds to complex and causes polymerisation (forms the loop) = pore forms

= lysis of cell.

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11
Q

What is the flow chart of adaptive immunity?

A

Common lymphoid precursor
= T cell = B cell
= CD4+ (helper) CD8+ (cytotoxic) = plasma cell

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12
Q

What is the difference in antigen receptors of B cells and T cells?

A

In T cells, they are non membrane bound molecules (get released) = T cell antigen receptor

In B cells, they are membrane bound
= surface immunoglobulin

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13
Q

What are the cellular components of the adaptive immune system and their functions?

A

B cell

  • activated by CD4+ cells
  • release cytokines
  • divide to give plasma and memory cells

T cytotoxic cell (CD8+)
- release perforin when cell is infected (destroys cell walls)

T helper cell (CD4+)

  • activated when CD4+ binds to an antigen on an antigen presenting cell
  • clones to form helper cells
  • activates B cells
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14
Q

What do plasma cells provide?

A

Antibodies

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15
Q

What are the humoral components of adaptive immunity?

A

1) . Cytokines (e.g. CD4+ activates B cells)
2) . Perforin - released by T cytotoxic cells to destroy cell walls
3) . Antibodies

16
Q

How do antibodies help with immunity?

A

1) . Neutralisation - bind to bacteria, preventing them from adhering to healthy cells
2) . Opsonisation - bind to bacteria and then are detected by receptors on macrophages = aids phagocytosis
3) . Complement activation - aids opsonisation.

17
Q

What is clonal selection in immunity?

A

Each lymphocyte has only one specific antigen = needs cloning before mounting an effective response.
This takes 3-5 days after the lymphocyte bearing the complimentary receptor to the foreign antigen is detected.

18
Q

What is the basic sequence of events in an adaptive immune response?

A

1) . Clonal selection
2) . Clonal expansion
3) . Differentiation to effector cells
4) . Antigen elimination
5) . T and B cell apoptosis

19
Q

Compare and contrast the innate and adaptive immune system.

A

Innate born with, adaptive is acquired.

Innate doesn’t have a memory, adaptive does.

Innate is non specific, adaptive has specific lymphocytes used

Innate is not enhanced by a second exposure, adaptive reacts much quicker due to presence of memory cells.

20
Q

How can complement be destroyed or deficient?

A

By heat

By genetic defect causing a deficiency in a specific complement.