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Flashcards in Pa20292 Deck (284)
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Why are IgG antibodies so important?

Most abundant AB type in the circulation
For secondary immune responses
Microbes coated in IgG - opsonisation and complement activation
AB dependent cell mediated cytotoxicity
IgG provide Foetus with humoral immunity

1

What activates cytotoxic T cells ?

Antigen presenting cells of class I MHC
Usually present viral fragments
Can also be stimulated by T helper Th1 cells

2

What shapes do each of the different classes of antibodies have? Ie monomer, dimer....

Monomers= IgE IgG
Dimers = IgA
Pentamers= IgM

3

The lectin complement cascade pathway involves.....

Mannose receptor binding to lectin and cleaving C4

4

What receptors (ABs) do B cells express once matured but before class switching?

IgM and IgD receptors

Remember; class switching and somatic hypermutations improve antibody affinity and function

5

How are NKcs activated ?

IL-12 from macrophages
Activates NKCs, they secrete IFNy
IFNy Feeds back and activates macrophage
(positive feedback loop)

6

Some features of neutrophils?

Granulocytes
Lysosomes inside
Large multi lobed nucleus
Lot of organelles
Contain antmicrobial enzymes
phagocytose

7

Do therapeutic antibodies tend to be polyclonal or monoclonal?

Monoclonal
Act against one particular epitope of an antigen
Activation of a single B cell= monoclonal response

8

Who were vaccinations discovered by and when?

By EDWARD JENNER
IN 1976

9

What cells is MHC protein present on?

Every cell apart from RBC's

10

What type of immunity do B cell produce?

Humoral immunity
Means antibody mediated immunity

11

Why do antibodies remain specific to a certain antigen for the rest of its life?

Because B cells undergo irreversible gene recombination to make it specific to a particular antigen, it can't change after this recombination as its irreversible.

12

What is inhibition of development of Th1 or Th2 cells by cytokine IL-4 and IL-12 known as?

Reciprocal inhibition

13

When activated, B cells swell in size. We call them _____

Plasma cells

Produces large numbers of antibodies

14

What do dendritic, macrophages and neutrophils have in common?

They are reactive oxygen and nitrogen species.
All engulf the antigen

15

Joining the constant region at the later mRNA stage in AB production, what does this allow?

Class switching at the later stages
The constant region of the heavy chain determines whether it's Ig A D M E or G

16

What do all 3 complement pathways result in the cleavage of?

C3--------> C3a + C3b
C3b leads to cleavage of C5--------> C5a + C5b

17

What classes can the 2 heavy chains of antibodies be?

Class A, D, E, G or M

18

What does high avidity of an AB mean?

They can bind a large number of AG's as they may be pentameric and have several binding sites, but usually bind with weak affinity.
Eg IgMs pentomer

19

What's HLA - B27 associated with?

Increased risk of ankylosing spondylitis
Chronic arthritis.
Majority of ppl with B-27 are healthy

20

What do lymphocytes have a large nucleus?

Involved with a lot of DNa transcription to make cytokines and antibodies

21

What are the only cells that can activate T helper cells?

Antigen presenting cells of class II MHC

22

igG antibodies are most abundant. Where Are these usually found?

In the circulation.

23

What cells do APCs present AG fragments to?

T cells

24

What are hypervariable regions also known as?

CDRs- complementary determining regions.

25

What are igA Antibodies for?

These target airborne antigens
Present at epithelial / mucosal surfaces (as this is where airborne antigens target)
Remember A for airborne
Generally found in lungs (we inhale airborne ABs)

26

Actions of T helper cells?

Activation of macrophages
Triggers phagocytosis
Enhance recruitment of neutrophils

27

How do T cells decide whether to be cytotoxic T cells or T helper cells?

In the thymus T cells mature and encounter a range of self antigens
Once they engage with an MHC it helps to determine what they will become

28

Do IgG and IgE antibodies have low or high avidity?

Low
They are monomers
Only have 2 antigen binding sites
But will have HIGH affinity

29

What are the cytokines IL-1 and TNF produced by?

Macrophages that have been activated by LPS
These are PROINFLAMMATORY
This is why an inflammatory response occurs with bacteria but not viruses.
Because bacteria contain LPS activating infflamation.

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