Introduction to Adaptive immunity

Question 1

What are the two branches of adaptive immunity?

Answer 1

B-cell immunity (humoral)

T-cell immunity (cellular)

Question 2

What components comprise B-cell immunity? What is it effective against?

Answer 2

Antibodies

Effective against extracellular pathogens

Question 3

What components comprise T-cell immunity? What is it effective against?

Answer 3

Helper T cells
Cytotoxic T cells
Effective against intracellular pathogens

Question 4

What are other nomenclatures for helper T cells?

Answer 4

CD4+ T cells

Th cells

Question 5

What are other nomenclatures for cytotoxic T cells

Answer 5

CD8+ T cells

CTL (cytotoxic lymphocytes)

Question 6

T cells and B cells are derived from which cells?

Answer 6

Lymphoid progenitor cells

Question 7

________ since immune response is more efficient with re-exposure to the same pathogen

Answer 7

adaptive

Question 8

Differentiate between the primary immune response and subsequent immune responses to the same pathogen for adaptive immunity. (Broadly)
Provide relative time frames for both.

Answer 8

During the primary immune response - magnitude is small. (takes ~5-10 days to develop)
The second, subsequent exposure will be both larger and faster, and overall more effective. (takes ~1-3 dys to develop)

Question 9

What is the purpose of vaccination?

Answer 9

To stimulate the adaptive immunity’s primary response so that subsequent exposure to the pathogen will be faster, stronger and more effective.

Question 10

Describe the development of memory cells after infection.

Answer 10

Naive B and T cells encouter an antigen (to which they are specific) for the first time. These will then develop into effector and memory cells.
Memory cells now have memory of that pathogen.

Question 11

Immunological memory is the basis for __________.

Answer 11

vaccination

Question 12

Do you develop more memory cells after subsequent exposures to the same pathogen?

Answer 12

Yes, this is the reason for a faster and stronger immune response after each, subsequent exposure.

Question 13

Summarize the first exposure response and subsequent exposure responses for adaptive immunity.

Answer 13

First exposure
- naive B and T cells develop into effector and memory cells

Second exposure
- memory cells respond to pathogen - more effective

Question 14

What are the two most important features of adaptive immunity?

Answer 14

Memory and specificity

Question 15

Where to B and T cells develop? Where specifically?

Answer 15

Primary lymphoid tissues
Bone marrow - B and T
Thymus - T

Question 16

Where do B cells develop?

Answer 16

Bone marrow

Question 17

Where to T cells develop?

Answer 17

Thymus

Question 18

Where are HSCs located?

Answer 18

The bone marrow

Question 19

Describe the path of lymphocytes from HSC to naive cells in circulation.

Answer 19

HSC –> lymphoid progenitor cells in the bone marrow.
Differentiate into naive B cells.
Naive B cells can enter the ciruclation.
T cells differentiate in the thymus then can enter the ciruclation as naive CD4 or CD8 cells.

Question 20

At which stage of life is the thymus largest? Why?

Answer 20

During infancy and when young. This is because the individual is constantly developing an immune response.

Question 21

What is immunosenescence?

Answer 21

over time, the immune system starts to get weaker at fighting off pathogens; don’t have development of T cells consntaly like when you were a child

Question 22

What are secondary lymphoid tissues?

Name them.

Answer 22

This is where naive B and T cells meet/respond to pathogens and become effector and memory cells. (i.e. where adaptive immunity is initiated).

Lymph nodes, spleen, MALT/GALT

Question 23

What are the different MALT areas?

Answer 23

Tonsils, adenoids, appendix, Peyer’s patch of small intestine

Question 24

What is the main characteristic of lymph nodes?

Answer 24

Filters lymph and is thus the location where B and T cells meet lymph-borne pathogens.

Question 25

In terms of location of cells, what is pertinent of secondary lymphoid tissues?

Answer 25

There are different zones for both B and T cells. (although they are sometimes found in very close proximity)

Question 26

Describe the path of blood to the lymph nodes.

Answer 26

Blood leaves the heart and reaches the capillaries. High pressure causes blood to leave the capillaries and enter the tissue - now referred to as interstitial fluid. This fluid is then picked up by the lymphatic system, and is now lymph. Lymph is then brought to lymph nodes to be filtered. B and T cells are located there and can mount an immune response, if need be.

Question 27

What does lymph remove from tissues?

Answer 27

Waste products - ex: dead cells, CO2, pathogens

Question 28

Describe the concept of intradermal vaccines.

Answer 28

Vaccine is administered into the dermis (i.e. tissues) and is picked up by the lymphatic system, to the closest lymph node. B and T cells there recognize the specific antigen and mount an immune response, developing memory.

Question 29

Describe the purpose of the spleen, and its role in adaptive immunity.

Answer 29

The spleen filters blood and thus is the site where B and T cells meet blood-bourne pathogens

Question 30

Which part of the spleen is the immune focused area?

Answer 30

White pulp

Question 31

Describe the role of the MALT in adaptive immunity. | What are MALT locations?

Answer 31

Site where B and T cells meet pathogens in mucosal areas. | Locations include the respiratory, GI and reproductive tracts

Question 32

_______ is the largest opening in the body, so provides an entrance for numerous pathogens.

Answer 32

mouth

Question 33

Which components of the MALT guard the entrance to the GI and respiratory tract?

Answer 33

Adenoids and Tonsils

Question 34

Why are tonsils often swollen in childhood?

Answer 34

Due to infections from many "first-time" pathogens

Question 35

What are reasons for removing and against removing tonsils?

Answer 35

Bad - near the largest opening - may be more susceptible | Good - there are so many areas to develop adaptive immunity that it probably doesn't matter

Question 36

What are the BCRs composed of?

Answer 36

Ig molecules

Question 37

Describe the BCR.

Answer 37

Composed of two chains, HC and LC (2 of each). The HCs are identical to each other; the LCs are identical (kappa-kappa or lambda-lambda) to one another. The tops of the receptor are called the variable region and are the areas that bind to the antigen. The constant chain/region is boudn to the cell memrbane and to the variable region.

Question 38

Describe the TCR.

Answer 38

composed of alpha and beta chains. top regions are variable regions and bind to the antigen. Constant region attached to variable and membrane region.

Question 39

How are TCRs and BCRs held onto the cell?

Answer 39

Transmembrane domains

Question 40

What is an antigen?

Answer 40

Any substance that a B and T cell can bind and mount an immune response against.

Question 41

How many antigens does a pathogen express?

Answer 41

Many different antigens.

Question 42

What is the part of an antigen that binds to the variable region of the BCR/TCR? What is another word for it?

Answer 42

Epitope or Antigenic epitope

Question 43

What is the binding between the variable region of BCR/TCR and an epitope based on?

Answer 43

Structural fit

Question 44

How does the BCR and TCR specificity arise?

Answer 44

Random rearrangement of variable region genes. i.e. for B cells - differnet HC and LC variable region genes associated for T cells - different alpha and beta variable region genes associate

Question 45

Which genes are those accounting for the variable region of BCR/TCRs?

Answer 45

VDJ genes

Question 46

How does each B/T cell have specificity to ONLY one antigenic epitope?

Answer 46

Each B/T cell expresses a BCR/TCR with its own unique variable region.

Question 47

Can antigens be self-molecules? Give an example?

Answer 47

Yes - RBCs express glycoprotein surface antigens which can be recognize during blood transfusions.

Question 48

What are the different markers that are possible on RBCs?

Answer 48

A, B, Rh factor

Question 49

What is the universal donor for blood?

Answer 49

O- - no surface markers

Question 50

What is the universal acceptor for blood?

Answer 50

AB+ - has no antibodies against any of the surface markers

Question 51

The B/T cell that binds an antigen undergoes what?

Answer 51

Mitosis = Clonal expansion which results in a "clone or army" of identical B/T cells with the same specificity