Cellular Immunity

Question 1

Where do T lymphocytes originate from

Answer 1

Bone marrow and mature in thymus

Question 2

What’s first evidence a T cell is going to form

Answer 2

2 coreceptor molecules (CD4+ and CD8+)
And T cell receptor

Question 3

What is CD8+

Answer 3

Cytotoxic T cell can recognise non self (viral infected cell) and kill it

Question 4

What is CD4+

Answer 4

Helper cell that recognises same type of antigen (MHC?) and produces numerous cytokines that provides signal for immune response

Question 5

What’s 4 main types of helper cells

Answer 5

Treg - dampens down immune response so u don’t undergo hyper immune response
Th1-cellular response
Th2-antibody response
Th17- inflammatory response

Question 6

Why is thymus largest at birth then shrinks

Answer 6

Because it’s active before birth as the entire T cell repertoire is generated before you’re born

Question 7

What do T cells learn in thymus

Answer 7

To recognise self MHC molecules. Most T cells die from neglect so don’t mature

Question 8

What’s human leukocyte antigens

Answer 8

Group of proteins on surface of cells that recognise self/non self antigens

Question 9

How does CTL kill non self tumours

Answer 9

Cytotoxic T cells (CTL) reacts to ur own cells when there’s change in MHC (when neo antigen) is expressed. Become activated and release granules to kill

Question 10

What’s self

Answer 10

Antigen encoded by MHC

Question 11

What’s non self

Answer 11

Antigen encoded by virus

Question 12

What is contacted by alpha helix which sits on top of MHC molecule

Answer 12

T cell receptor. When self peptide on MHC molecule changes to non self peptide then T cells recognise the difference&raquo_space; starts adaptive immune response

Question 13

What does CD4 and CD8 cells recognise

Answer 13

CD4 - helper T cells, Antigens in MHC class II
CD8 - cytotoxic T cells, antigens in MHC class I

Question 14

How does CD4 and CD8 initiate T cell signalling

Answer 14

Has kinases associated with cytoplasmic tails and initiate signalling through phosphorylation

Question 15

What’s T cell help in CD4+ helper function

Answer 15

When T cells proliferate and produce cytokines. Helps immune response
Mechanism required for B cells to make antibodies

Question 16

What’s killing

Answer 16

CD8+ cytotoxic kills viral infected cell by producing granzymes and perforins that punch holes in cell membrane and destroy cell viability

Question 17

Summary MHC class 1

Answer 17

Antigens from inside cell primarily through viruses.
Responding T cells = CD8
Function is to kill - cytotoxic

Question 18

Summary MHC class II

Answer 18

Expressed primarily on antigen presenting cells (extracellular) engulf bacteria > broken down to stimulate CD4 cells to create help

Question 19

What’s MHC polymorphism

Answer 19

MHC amino acid sequence varies greatly.
Hundreds of variations at each MHC locus.
Polymorphism restricted to protein domains that form peptide groove.
12 total polymorphic molecules expressed on ur cells and no one shares exactly same MHC profile apart from identical twins

Question 20

Why is MHC polymorphic

Answer 20

It’s a form of natural selection to diversify populations response to new pathogens

Question 21

Consequences of MHC polymorphism

Answer 21

1. Tissue transplant is difficult as donor MHC is non self and rejected by recipients T cells. Requires tissue typing for donor selection
2. MHC polymorphisms strongly linked to autoimmune diseases