15 Lymphocytes Flashcards

1
Q

Lymphocytes are derived from

A

Common lymphoid progenitors

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2
Q

Common lymphoid progenitors are found in the

A

Bone marrow

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3
Q

Key characteristics of adaptive immunity

A
  • Fight against recurring infections
  • Specificity to clear infection
  • Has memory
  • Focuses response on the site of infection (+ specific organism responsible)
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4
Q

Immunological memory occurs when

A

The immune system has recognised and responded toan antigen

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5
Q

What is the basis of immunological memory?

A

Antigen specific lymphocytes (B+T)

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6
Q

Memory responses are…

A
  • More rapid and heightened immune responses

- Eliminate pathogens fast and prevent disease

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7
Q

Two families of lymphocytes

A
  • B cells (humoral) –> antibodies

- T cells (cell-mediated) –> cytokines, killing

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8
Q

What is an antigen?

A

Molecules that induce an adaptive immune response (mostly protein)

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9
Q

What is an epitope?

A

The region of an antigen which the receptor binds to

‘small molecular fingerprint’

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10
Q

T cells can recognise

A

Linear epitopes (primary structure) in the context of MHC

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11
Q

B cells / antibodies can recognise

A

Structural epitopes (tertiary structure, folding)

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12
Q

Why do vaccines have to be kept cold?

A

To prevent the proteins from changing shape –> immune response would not match

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13
Q

To respond to many, different antigens

A

A very large pool of cells with specific receptors is needed

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14
Q

How is antigen receptor diversity generated?

A

Through recombination

- Different V + J regions can combine in different ways

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15
Q

What is immunoglobulin gene rearrangement?

A
  • each BCR receptor chain is encoded by separate multigene families on different chromosomes
  • During B cell maturation, these gene segments are rearranged and brought together
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16
Q

Immunoglobulin gene rearrangement generates

A

Diversity of the lymphocyte repertoire

17
Q

How are T helper cells and cytotoxic cells activated?

A

Binding to an APC presenting an antigen to which that T cell is a perfect match

18
Q

What does T helper cell activation due?

A

The activated T helper cell divides forming a clone army which:

  • Signals to help other cells
  • Attacks, defends, repairs
  • Causes allergies
  • Immune memory
19
Q

What does cytotoxic cell activation due?

A

The activated T killer cell divides forming a clone army which:

  • Signals to other cells
  • Becomes powerful killers (killing pathogens, harmful/infected cells)
  • Immune memory
20
Q

What is the T cell receptor?

A

Part of a complex of proteins on the cell surface

  • Variable region made by gene reassortment
  • Recognises antigen fragments presented by other cells
21
Q

What is the MHC?

A

-Encoded by HLA genes
- Presents antigen to T cells
- Defines self and non self
(crucial in surgery + donor matching)

22
Q

MHC gene expression

A
  • Polygenic, several class I and II loci

- Expression is co-dominant (both maternal and paternal expressed)

23
Q

MHC class I

A
  • All nucleated cells

- Various levels, altered during infection/by cytokines

24
Q

MHC class II

A
  • Only on professional APCs

- May be regulated by cytokines

25
MHC I Process in? Type? Presented to?
Proteins being produced inside the cell - Cytosol - intracellular pathogen/antigen - CD8 T cells (killer)
26
MHC II Process in? Type? Presented to?
Resident in tissues/in circulation - Endosomes - Extracellular pathogen/antigen - CD4 cells
27
Two families of T cells
- CD4 (helper) - CD8 (killer) Defined by cell surface molecules CD4 and CD8
28
How do CD8 cell kill targets?
Programmed cell death (apoptosis) - Fragmentation of nuclear DNA - Perforin (polymerise forming pores) - Granzymes (poisons inserted into cell)
29
Viruses: Apoptosis or necrosis?
Apoptosis, as necrosis would release viral particles
30
Function of CD4 T helper cells
- Produce cytokines (inflammatory mediators) | influence outcome of immune response
31
Tfh
- Pro-antibody | - IL-21
32
Th1
- Pro-inflammatory - Boost cellular immune response - Interferon gamme, timour necrosis factor, IL-12
33
Th2
- Pro allergic - Boost multicellular response - Il-4, IL-5, IL-13
34
Th17
- Pro inflammtory - Control bacterial and fungal infection - IL-17, IL-23, IL-6
35
Treg (Th0)
- Anti-inflammtory - Limit the immune response - IL-10, TGFB
36
SLIDE 28
B cells and onwards