Developing And Maintaining Adaptive Immunity

Question 1

Antigen specificity

Answer 1

Every cell has a unique receptor which binds to a specific antigen

Question 2

Naive cells

Answer 2

Cells which have never been activated

Question 3

Effector cells

Answer 3

When cells become activated

Question 4

Memory cells

Answer 4

Once the cells have been activated

Question 5

B cells

Answer 5

Antibody producing cells - once activated become Plasma cells

Question 6

Plasma cells

Answer 6

Activated B cells

Produce antibodies which bind to a specific antigen

Question 7

Antibodies

Answer 7

Are y-shaped and soluble, they circulate in the blood and bodily fluids, bind to pathogens and either… kill them, mark them for killing or prevent them from spreading

Question 8

CD4+ helper T cells

Answer 8

Organise immune responses -> produce different cytokines - can differentiate into different cell types

Question 9

CD8+ cytotoxic T lymphocyte

Answer 9

Kills infected/mutated cells by giving them a signal to die via apoptosis

Question 10

Clonal selection

Answer 10

T/B cells express receptors of random specificity that only recognise one antigen -? Specific T/B cell binds pathogen causing proliferation -> T/B cell expands population, immune response kills pathogen -> daughter cells produced express identical receptors to the parent -> T/B cell pool now contains increased precursor frequency of pathogen-specific cells

Question 11

Hematopoietic stem cells

Answer 11

What B and T cells arise from

Question 12

BcR

Answer 12

B-cell receptor

Question 13

TCR

Answer 13

T cell receptor

Question 14

Variable, diversity and joining gene segments

Answer 14

Encode for variable regions in BcRs and TcRs

Question 15

Somatic recombination

Answer 15

Random pairing of one Variable, one joining and one diversity region

Question 16

Junctional diversity

Answer 16

Extra/fewer nucleotides at VDJ junctions

Question 17

Combinatorial diversity

Answer 17

Different alpha/beta combinations, different VDJ combinations, Different heavy/light chain combinations

Question 18

B cell receptor and antibodies

Answer 18

Recognise soluble antigens in their normal form

Question 19

T cell receptor interactions with antigens

Answer 19

TcRs cannot recognise antigens in their normal form so must have antigen presented to it on Major Histocompatibility Complex (MHC) molecules on another cells

Antigens must be broken down into peptides then loaded onto MHC molecules and presented on the surface of the cell

Question 20

Class 1 MHC

Answer 20

On all nucleated cells apart from neurones
Presents only endogenous antigens (proteins from within the cell)
Antigen bound only by CD8+ cytotoxic cells
If antigen presented is non self then cell is killed by CD8+

Question 21

Class 2 MHC

Answer 21

Only on antigen presenting cells - e.g. dendritic cells
Presents exogenous antigens (proteins outside the cell)
More associated with CD4+ T helper cells

Question 22

Polymorphism

Answer 22

Multiple variants of a gene within the human population

Cause of diversity in MHC

Question 23

Co-expression

Answer 23

Alleles inherited from mother and father

Results in diversity in MHC

Question 24

Polygyny

Answer 24

Multiple independent genes for each MHC type

Cause of diversity in MHC

Question 25

Central tolerance

Answer 25

Deletion of self reactive T-cells in the thymus and self reactive B cells in bone marrow

Question 26

Criteria for deletion if self reactive T cells

Answer 26

Ability to bind to MHC

Strength of binding to MHC presenting self-peptide

Question 27

Positive selection

Answer 27

Post binding signalling to MHC allows T cell survival

Question 28

Negative selection

Answer 28

Strong binding of T cells to MHC causes death

Question 29

Peripheral tolerance

Answer 29

Dendritic cells require 2 signals - MHC and Co-stimulation in order to activate T-cells

Question 30

T-regulatory cells

Answer 30

Caused by T-cells being activated by immature dendritic cells

Switch off adaptive and innate immune responses through the production of cytokines that dampen immune response - IL-10

Question 31

Inducible Tregs (iTregs)

Answer 31

Recognise self or environmental antigens - arise in the periphery

Question 32

Natural Tregs (nTregs)

Answer 32

Recognise self antigens - arise in thymus