E-Learning Adaptive Immune System

Question 1

What are the 2 types of adaptive immunity? [2]

Answer 1

Cell-mediated - T cells

Humoral - Abs from B cells

Question 2

Overall what do Th cells do? [5]

Answer 2

Respond to MHC2 on APCs:

• Cytokine release
• Growth/activation of Tc Cells
• To maximize phagocyte activity
• B cell Ab class switching

Question 3

What do Th1 cells specifically do? [2]`

Answer 3

Secrete IFN gamma, IL1, TNF alpha
Activate macrophages, NK cells and CTLs
Protect against intracellular pathogens
Disease role in autoimmunity and chronic inflammation

Question 4

What do Th2 cells do specifically? [2]

Answer 4

Secrete IL-4, 5, 6, 10, 13
Activate B cells to produce abs
Target extracellular pathogens like helminths
Disease role in allergy

Question 5

What do Th17 cells do? [2]

Answer 5

Secrete IL 17 and IL 22
Activate PMNs and monocytes
Protect against extracellular pathogens
Disease role in autoimmunity and chronic inflammation

Question 6

What can CD8 T cells do? [3]

Answer 6

1) Release Anti-tumour/viral IFN & TNFalpha
2) Release perforin & granzymes –> Apoptosis
3) Release FasL –> Apoptosis

Question 7

What do Treg cells do? [2]

Answer 7

Suppress immune response and inflammation by IL-10 & TGF-beta

Question 8

We have T cells with a wide variety of TCR binding sites so we can recognise lots of pathogenic antigens. How does this occur? [2]

Answer 8

During maturation in the thymus T cells undergo VDJ recombination –> Varied TCRs

Question 9

Where do naïve T cells differentiate into Th or Tc cells?

Answer 9

Secondary Lymphoid Organs once presented with their complementary Antigens

Question 10

How do we end up with highly varied BCR binding sites? [1]

Answer 10

By VDJ recombination during maturation of B cells in the bone marrow

Question 11

How can B cells be activated? [3]

Answer 11

1) T cell dependant
2) T cell independent (antigens in secondary lymphoid organs)
3) Memory B cell Activation

Question 12

What happens to B cells after activation? [2]

Answer 12

Two options:
1) Become short lived plasma cells that produce IgM or IgG

2) Undergo class switching in germinal centres –> becoming long-lived plasma cells or Memory B cells

Question 13

Describe the structure of an antibody? [2]

Answer 13

The trunk or FC region is constant. this is what communicates with other immune cells and is all heavy chain

The stalks or FAB region are variable, they bind to antigens

Question 14

Most Immunoglobulins are monomers, which aren’t? [2]

Answer 14

IgM is a pentamer

IgA is a Dimer

Question 15

Which Abs are produced in immune response to pathogens? [2]

Answer 15

IgM first then IgG

Question 16

Which Ab can cross the placenta?

Answer 16

IgG

Question 17

Which Ab targets parasites and is involved in allergy?

Answer 17

IgE

Question 18

What can Abs do? [4]

Answer 18

1) Form Ab-Ag complexes
2) Opsonise for phagocytes
3) Activate complement (classical pathway)
4) Ab mediated Cellular Cytotoxicity

Question 19

How does Ab production change after the 1st and 2nd exposure? [2]

Answer 19

In the first exposure you get a lag, then IgM spike then IgG spike

In 2nd exposure the IgM comes quicker and lower, then the IgG spikes higher and for much longer

Question 20

What makes up immunological memory? [2]

Answer 20

Memory B cells

Memory T Cells (both CD4 & CD8)