(LE3) Adaptive Immunology

Question 1

What is the main difference between the innate immune response and the adaptive immune response?

Answer 1

It is pathogen specific, so it is slower

Question 2

What is an antigen?

Answer 2

antibody generator - anything that triggers an adaptive immune response (foreign molecule)

Question 3

Why don’t we usually build immunity against Gram-negative infections?

Answer 3

LPS they contain make weak antigens
- proteins and glycoproteins make better antigens

Question 4

Where are antigens found on a pathogen?

Answer 4

usually on surface of pathogen (wall, capsule, virus coat)
- internal antigen can be released with the death of the pathogen

Question 5

Why is the adaptive immune response slower?

Answer 5

specificity
- it is pathogen-specific so the response against one pathogen does not function against another pathogen

Question 6

How does our adaptive immune response not attack our own cells?

Answer 6

Self vs. Non-self recognition
- response ignores self Ag and attacks non-self

Question 7

What is diversity when referring to the adaptive immune response?

Answer 7

Can respond to large number of Ags, even those that we are rarely/never exposed to (naive WBCs)

Question 8

How do we gain active immunity from the adaptive immune response?

Answer 8

Immune response remembers pathogen after it is cleared, waiting for the next exposure

Question 9

What are the two branches of adaptive immune response?

Answer 9

1. Humoral immunity
2. Cell mediated immunity

Question 10

What is the function of Humoral Immunity?

Answer 10

Fights invaders outside cells (e.g. bacteria and toxins)
- B-lymphocytes (antibodies)

Question 11

What is the function of cell-mediated immunity?

Answer 11

Fights invaders found inside cells (e.g. viruses and cancer)
- T-lymphocytes (kill infected cells)
- antigen-presenting cells (macrophages, dendritic cells, etc.)

Question 12

How are B cells activated?

Answer 12

• only lymphocyte with specific receptor to Ag will be activated
• B lymphocytes activate when they bind to their Ag for first time
• clonal selection begins

Question 13

What is clonal selection?

Answer 13

B lymphocytes proliferate and differentiate into Plasma cells and memory cells

Question 14

What do plasma B-cells do?

Answer 14

Secrete antibodies specific to antigen

Question 15

What do memory B-cells do?

Answer 15

stay in circulation to recognize pathogen upon subsequent exposure

Question 16

What are antibodies, and what is their composition?

Answer 16

Immunoglobulins, serum proteins

2 heavy chains + 2 light chains held together by disulfide bonds

Question 17

What region of the antibody is indicated?

Answer 17

Constant region (Fc) - 5 classes

Question 18

What region of the antibody is indicated?

Answer 18

Variable region - Ag binding sites

Question 19

What are the protective mechanisms of binding antibodies to antigens?

Answer 19

• agglutination
• opsonization
• neutralization
• activation of complement system
• antibody-dependent cell-mediated cytotoxicity

Question 20

What does antibody agglutination do?

Answer 20

And facilitates phagocytosis

Question 21

What does antibody complement activation do?

Answer 21

(classical activation)

Question 22

What is antibody opsonization?

Answer 22

• facilitate phagocytosis
• neutralize

Question 23

What does antibody-dependent cell-mediated cytotoxicity do?

Answer 23

NK cells destroy Ab-bound infected cells/tumors

Question 24

What is Ag neutralization?

Answer 24

Question 25

What class of antibody is pictured? What is their function?

Answer 25

IgG - most prevalent in blood & most effective antibody - opsonization and activates complement system - can cross placenta (passive immunity)

Question 26

What class of antibody is pictured? What is their function?

Answer 26

IgM (pentamer) - first to appear - agglutination

Question 27

What class of antibody is pictured? What is their function?

Answer 27

IgA (monomer or dimer) - in mucus membranes (monomer) and secretions (dimers). e.g. breast milk - Prevents pathogen attachment to mucus membranes; neutralization

Question 28

What class of antibody is pictured? What is their function?

Answer 28

IgD - Ag receptor on B cells

Question 29

What class of antibody is pictured? What is their function?

Answer 29

IgE - allergic response and parasitic worms

Question 30

What is primary response?

Answer 30

First exposure to an antigen - slow to develop - IgM first then IgG - total Ab titer lower - creates memory B cells that stay in blood and lymph

Question 31

What is secondary response?

Answer 31

Subsequent exposures to an antigen - very fast to develop - quickly produces large amounts of IgG - leads to immunity

Question 32

What is clonal deletion?

Answer 32

Removes B-cells that recognize self Ags - happens in utero during fetal development - prevents your immune system from attacking your own cells

Question 33

How are autoimmune disorders theorized to occur? What is an example?

Answer 33

Immune system attacks self-Ag - e.g. Rheumatoid arthritis, T1 Diabetes

Question 34

Where do T-cells encounter their Ag?

Answer 34

Has to be presented on the surface of cells

Question 35

What are APCs?

Answer 35

Antigen Presenting Cells phagocytes that engulf pathogen and present pieces of it on the cell surface

Question 36

What conditions must be met for naive T-cell activation and proliferation?

Answer 36

Recognition of Ag on T-cell receptor Recognition of MHC on Co-receptor

Question 37

Where are MHC II found?

Answer 37

Phagocytes - mø - dendritic cells - B-cells

Question 38

Where are MHC I found?

Answer 38

All nucleated cells

Question 39

What co-receptor is recognized by MHC II? MHC I?

Answer 39

Question 40

What antigen source is processed by MHC I? MHC II?

Answer 40

MHC I: intracellular virus or cancer MHC II: pathogens

Question 41

What are the two types of T cells?

Answer 41

- Cytotoxic T cells (CD8) - Helper T cells (CD4)

Question 42

What do Helper T cells do?

Answer 42

- Coordinate both humoral and cell-mediated immune response - assist in lymphocyte and mø activation by producing cytokines

Question 43

How does HIV attack our immune system?

Answer 43

Targets CD4 cells, commander of entire system. destroys immune system, leads to AIDS

Question 44

What are cytokines?

Answer 44

intercellular chemicals that stimulate/inhibit growth and activity of their leukocytes

Question 45

What do TH1 cells do?

Answer 45

- secrete IL-2 and gamma-interferon - enhance cell-mediated response (virus) - Help activate CD8 cells and Mø - suppress B cell activation

Question 46

What do TH2 cells do?

Answer 46

- secrete IL-4 and IL-5 - enhance humoral response (extracellular pathogen) - help activate B cells (T-cell dependent activation) - suppress CD8 activation

Question 47

How do Cytotoxic T cells function?

Answer 47

- kill cells by releasing perforin (pokes holes in cell membrane)

Question 48

What is the humoral response best for?

Answer 48

Circulating pathogens and toxins (blood and lymph) - T-cell dependent B-cell activation - T-cell independent B-cell activation - Antibody dependent cell mediated cytotoxicity (ADCC)

Question 49

Describe T-cell-dependent B-cell activation

Answer 49

TH2 release IL-4 and IL-5 - stronger but slower response

Question 50

Describe T-cell independent B-cell activation

Answer 50

No T-cells or cytokines - weaker but faster response

Question 51

What is the cell-mediated response best for?

Answer 51

Virus-infected cells and tumors - strong memory - develops more slowly