Lecture 7: Adaptive Immunity

Question 1

What are the three key features of the adaptive immune system? What is required for these features to occur?

Answer 1

It is specific, it is systemic, and it has memory. Antigen recognition is required for features to occur.

Question 2

B cells and T cells are derived from the common _______ _________ in the ____ ____ _____.

Answer 2

Lymphoid progenitor, red bone marrow

Question 3

Where are B cells developed? T cells? What do they develop?

Answer 3

B cells are developed in bone marrow, T cells developed in thymus. They develop immunocompetence and self-tolerance.

Question 4

After developed, where do B and T cells go?

Answer 4

Lymph nodes

Question 5

What 3 things are special about B and T cells?

Answer 5

1. long life span
2. can regenerate quickly
3. each have a unique receptor to recognize antigen

Question 6

What is different about B and T cells?

Answer 6

1. they develop at different sites
2. B has 2 antigen recognition sites, T has 1
3. B can be membrane bond or an antibody, T is always membrane bound

Question 7

What are the 3 regions of a receptor? How are they so specific?

Answer 7

3 regions = V, D, J
Specific because there is an almost unlimited number of combinations.

Question 8

What are the 2 types of T cells? What do they do?

Answer 8

CD4 cells are “helpers” and help recognize antigens & activate B cells.
CD8 cells are cytotoxic, recognize antigens, and kill infected cells.

Question 9

Define antigen.

Answer 9

Any molecule that can bind specifically to an antibody.

Question 10

Define epitope.

Answer 10

A small structure on an antigen that can induce an immune response by binding an antibody/receptor on B or T cell.

Question 11

What is MHC (Major Histocompatibility Complex)?

Answer 11

Glycoproteins found in plasma membrane of all vertebrates, everyone has a unique MHC.

Question 12

Define the 2 classes of MHCs.

Answer 12

1. in plasma membrane of all nucleated cells.
2. on professional antigen-presenting cells.

Question 13

What do Professional Antigen Presenting Cells (APCs) do? What type of cells are best at being APCs?

Answer 13

Process/display antigenic peptides on cell-surface molecules, activate T cells. Dendritic cells.

Question 14

T cells can only see antigens if they’re presented on what?

Answer 14

An MHC molecule

Question 15

What do MHC Class 1 molecules do when a pathogen enters a cell? What type of antigen is this?

Answer 15

Presents antigen to CD8+ T cells. Endogenous.

Question 16

What do MHC Class 2 molecules do when a pathogen enters a cell? What type of antigen is this?

Answer 16

Binds peptides from intracellular vesicles, presents antigen to CD4+ cells. Exogenous antigen.

Question 17

What are the two divisions of the adaptive immune system?

Answer 17

Humoral and cell-mediated immunity.

Question 18

Humoral immunity is ____ mediated, which are produced by ___ cells. It binds to ______ and _______.

Answer 18

Antibody, B, bacteria, toxins

Question 19

Cell-mediated immunity is mediated by ____ cells and has ______ ________. It is largely mediated by ___ cells and kills ______ and _______ cells.

Answer 19

Living, cellular targets, T, infected, cancer

Question 20

Once a naive T cell is activated, what is it now called? What are examples of these?

Answer 20

An effector T cell. Ex. cytotoxic, helper, memory, regulatory T cells.

Question 21

What do signals 1 and 2 indicate for the T cell? Signal 3?

Answer 21

1/2 = activate a naive T cell
3 = indicate instructions

Question 22

What is proliferation and differentiation of activated T cells called?

Answer 22

Clonal selection

Question 23

How do activated cytotoxic T cells kill cells?

Answer 23

Perforin = forms hole in cell membrane
Granzyme = enters and kills cell

Question 24

T or F: memory T cells require stimulation for activation

Answer 24

False

Question 25

What do B cells proliferate and differentiate into?

Answer 25

Plasma cells = secrete antibodies Memory B cells = await subsequent exposure

Question 26

How are T and B cells different in terms of activation?

Answer 26

B cells can "see" the antigen through their own receptors, T cells cannot

Question 27

Name the 3 steps of B-Cell activation.

Answer 27

1. B cell internalizes bound antigen 2. Processes and presents its MHCII 3. A matching T helper cell provides a second signal.

Question 28

What does the core structure of an antibody consist of?

Answer 28

2 identical heavy chains (5 types) 2 identical light chains (2 types)

Question 29

Which two regions are present on each chain of the antibody?

Answer 29

A variable region = responsible for antigen recognition Constant region = structural stability

Question 30

Different _______ determine roles and functions of antibody.

Answer 30

Isotypes

Question 31

What are the 5 classes of isotypes?

Answer 31

IgM IgA IgD IgG IgE

Question 32

What are the three groups of isotypes?

Answer 32

Monomer: D, G, E Dimer = A Pentamer = M

Question 33

How doe Abs protect us from pathogens?

Answer 33

Neutralize antigens/toxins Prevent virus attachment to cells Immobilize bacteria Enhance phagocytosis Activate complement/kill bacteria

Question 34

What are components of the primary immune response?

Answer 34

Steady, slow. Memory cells may remain for decades. Occurs 3-6 days after exposure, fall after 28 days.

Question 35

What occurs during the secondary immune response?

Answer 35

Occurs following re-exposure, faster/stronger/more prolonged than 1st response (within hours). Pathogen is destroyed before multiplication.