Adaptive Immune system

Question 1

What is adaptive Immune response?

Answer 1

The adaptive immune response consists of cell-mediated responses and antibody (humoral) responses

Question 2

What cells drive cell-mediated immunity?

Answer 2

T-cells

Question 3

describe B cells in terms of adaptive immune system

Answer 3

B cells produce antibodies and drive humoral immunity

Question 4

What is meant by immunological memory?

Answer 4

Whereby pattern recognition receptors recognize any microbes, T cell and B cell receptors are specific for components of a certain pathogen (eg antigen)

Question 5

When does the kinetics of adaptive immune system kick in?

Answer 5

> 4-7 days

Question 6

What is the threshold level of antigen and why is it important?

Answer 6

the “amount” of a pathogen present to mediate an immune response
This is important as the immune system does not need to mediate adaptive immunity if only a small amount of antigen present – e.g., innate immunity can clear the threat without help of adaptive immunity

Question 7

What are the three main receptors in adaptive immunity?

Answer 7

T cell Receptor (TCR)
B cell Receptor (Immunoglobulins[Ig])
Major histocompatibility complex (MHC proteins)

Question 8

T cells are derived from bone marrow however where do they mature?

Answer 8

Thymus

Question 9

What do T-cells give rise to?

Answer 9

cellular immunity

Question 10

What are the main types of Tcell receptors circulating?

Answer 10

alpha and beta chains
(beta and delta more uncommon-5%)

Question 11

What two gene segment codes for the alpha chain?

Answer 11

V&J (variable and joining)

Question 12

What three gene segment codes for Beta chain?

Answer 12

V,D, J (variable, diversity and joining)

Question 13

What region has multiple antigen binding sites and can change shape (recombination)?

Answer 13

Variable region

Question 14

What are the two types of selection when Tcells interact with thymic cortical epithelial cells?

Answer 14

Positive selection, negative selection

Question 15

what is positive selection of T-cells?

Answer 15

No recognition = apoptosis

Question 16

What is negative selection of T-cells?

Answer 16

Recognition of self antigen = apoptosis

Question 17

What do all T cells start as?

Answer 17

Naive cells

Question 18

What are the three signals required for activation and determining fate of T-cells?

Answer 18

1’ MHC-TCR interaction
2’ co-stimulatory molecules interactions (CD80/CD86 and CD40 on DC —- CD40L and CD28 on T cell)
3’ signal dictates what T helper cell the naïve cell become

Question 19

What enzymes induce target cell apoptosis?

Answer 19

perforin and granzyme

Question 20

What do Cytotoxic T cells (CD8+) do?

Answer 20

destroy infected host cells by inducing apoptosis

Question 21

What are B cells?

Answer 21

They produce antibodies and have a specific receptor for antigens

Question 22

clonal expansion of b-cells results in what two subsets?

Answer 22

plasma cells and memory b cells

Question 23

Where do B cells mature

Answer 23

bone marrow

Question 24

What are the three main receptors in adaptive immunity?

Answer 24

T cell Receptor
B cell receptor
major histocompatibility complex

Question 25

What are the five immunoglobulins produced by B cells?

Answer 25

IgG, IgE, IgD, IgM and IgA

Question 26

What is a function of IgG?

Answer 26

most prominent antibody in body, resistance of most viruses- 4 subsets

Question 27

What is a function of IgE?

Answer 27

exposed on surface of basophils and mast cells

Question 28

What is a function of IgA?

Answer 28

found in glandular secretions- mucus, saliva and tears- 2 subsets

Question 29

What is a function of IgD?

Answer 29

found on surface of B cells and can bind to antigens in extracellular fluids B cell receptor

Question 30

What is the function of IgM?

Answer 30

capable of binding to multiple antigens-blood

Question 31

What is the B cell receptor structure?

Answer 31

have varible and constant regions (like T) have light and heavy chains

Question 32

An immature receptor is mainly what immunoglobulin?

Answer 32

IgM

Question 33

Describe B cell negative selection

Answer 33

Like the TCR there is great diversity in the B cell receptor repertoire. Need to ensure that there is no reactivity against self antigens. B cells undergo negative selection in bone marrow. Macrophages will engulf and remove self-reacting B cells.

Question 34

What are the three main functions for antibodies in the human body?

Answer 34

Neutralization Opsonization Initiation of complement

Question 35

What is meant by opsonization?

Answer 35

Opsonisation refers to coating of pathogens by antibodies or complement proteins Phagocytosis Antibody dependent cellular cytotoxicity (ADCC) Mast cell degranulation

Question 36

in compliment iniitiation what is meant by the classical pathway?

Answer 36

antibody attached to microbe

Question 37

diversity of antibody specificity involves what?

Answer 37

gene re-arrangements during development

Question 38

What are the two types of B cell activation?

Answer 38

Thymus-dependent antigen Thymus-independent antigen activation (no T cells)

Question 39

Activation of naive B cells results in rise of what?

Answer 39

plasma cells

Question 40

What is meant by affintiy?

Answer 40

= strength of binding of single antibody to antigen

Question 41

What is meant by avidity?

Answer 41

ability of antibodies to form complexes

Question 42

What role do B and T cells play in vaccinations?

Answer 42

Antigen exposure leads to immunological memory. In the primary immune response IgM acts early but as B cells undergo class switching an IgG response follows. Presence of memory T and B cells means that upon a second exposure the immune system can respond much faster. In addition, we have cells that are primed to produce a more effective IgG (rather than IgM) response immediately

Question 43

what is immunological tolerance?

Answer 43

Sometimes the immune system can become dysfunctional and in a state of immune unresponsiveness to a particular antigen or set of antigens (immune tolerance). allergies

Question 44

What signal determines the subset the cell differs into?

Answer 44

third

Question 45

What does breach of tolerance result in?

Answer 45

self antigens drives many autoimmune disease