Immunology - Adaptive Immunity

Question 1

Describe adaptive immunity
Specific or not specific?
Fast?
Activation needed?
Memory?
Which are the main cells involved?

Answer 1

Specific
Slow
Need activation
Have memory
Killing usually antibody mediated
Main cells are T & B (+ plasma) cells

Question 2

Where are T cells produced and mature?

Answer 2

Produced in Bone marrow, mature in thymus

Question 3

What is the process called that chooses which T cells are good?

Answer 3

Thymic tolerance

Question 4

What happens in positive selection?

Answer 4

T cells tested to see if they recognize thymus MHCs (major histocompatibility complex) (1+2), they are then selected for

Question 5

What happens in negative selection?

Answer 5

If T cells produce immune response, selected against

Question 6

What happens in allocation?

Answer 6

If T cells interact with:
MHC 1 = CD8+ cells (Tc)
MHC2 = CD4+ cells (Th)

Question 7

CD8+ (Tc) cells
What do they interact with?
Function?

Answer 7

Interact with MHC 1
Direct cytotoxic killing

Question 8

How do CD8+ cells kill? 2 ways?

Answer 8

1. Perforin secretion (mediated by granzyme B)
2. Express FasL - activates caspases

Question 9

What’s a naive T cell?

Answer 9

T cell never encountering antigen (not treated in thymus yet)

Question 10

Who do CD4+ (Th) cells interact with?
What are the 2 types of Th cells?

Answer 10

Interact with MHC 2

Th1 & 2

Question 11

What do Th1 cells do?

Answer 11

IFN-Y
Activate NK cells and macrophages (increase innate response)

Question 12

What do Th2 cells do?

Answer 12

Activate B cells to differentiate into plasma cells (increase adaptive response)

Question 13

Where do B cells produce and mature?
What happens to B cells that launch immunity to themselves?

Answer 13

Bone marrow
Apoptosis

Question 14

How is Th2 activated? What does it release?

Answer 14

Activated by APC and MHC 2 interaction (eg. With dendritic cell)

Th2 release:
IL4 which induces B cell proliferation (clonal expression)
IL5 which induces B cell differentiation into plasma cell - produce (GAMED) Ig

Question 15

Ig’s act vs specific pathogen present but if need arises?

Answer 15

A.I.D
Activation induced cysteine deaminase does 2 things

Question 16

What can A.I.D do?

Answer 16

1. Produce pant mutations in Ig as ‘evolutionary measure’ - somatic hyper mutation
2. Induce class switching (mutate GAMED to another isotope)
   IL4 - promotes class switching to IgA
   IL5 - promotes class switching to IgE (allergic response)

Question 17

Describe IgG

Answer 17

Most abundant Ig in blood

Key in 2^ immune response (marker of immune memory), very specific

IgG 1,2,3,4 subtypes

Question 18

Describe IgA

Answer 18

Most abundant Ig in total body

Found on mucosal lining & in colostrum/breast milk

Forms DIMER

Question 19

Describe IgM

Answer 19

First Ig released in adaptive response
Less specific

Forms pentamer

Question 20

Describe IgE

Answer 20

IgE activates mast cells and basophil degranulation in T1 hypersensitivity
Anaphylaxis

Question 21

Describe IgD

Answer 21

Unknown function

Presumed to be B cell receptor components

Question 22

What does MHC stand for?
Where are they found?
What are they also?

Answer 22

Major histocompatibility complex
On chromosome 6
HLA (human leukocyte antigen) molecules

Question 23

What are the 2 functions of MHCs?

Answer 23

1. Interactions with T cells
   Th (CD4+) interact with MHC2 - on APCs
   Tc (CD8+) interact with MHC1 on all nucleated cells (not RBC)
2. Confer susceptibility to inherited autoimmune diseases
   HLAB27 - spondyloarthropathies
   HLADR2DQ3 - T1DM
   HLA DQ2/DQ8 - coeliacs