Lecture 27- Adaptive Immunity

Question 1

Adaptive Immunity

Answer 1

Specific immune response- specific to each pathogen
Several days to mobilize (innate immunity is faster)

Question 2

Lymphocytes

Answer 2

Types of white blood cells, originate in marrow
2 types involved in adaptive immunity
B cells- mature in marrow
T cells- mature in thymus

Question 3

Where do B cells mature?

Answer 3

Bone marrow

Question 4

Where do T cells mature?

Answer 4

Thymus

Question 5

Antigen (Ag)

Answer 5

Any foreign substance that elicits B or T cell response
Mostly proteins or polysaccharides on foreign organism
Epitope: Specific region exposed on surface of Ag
Specifically binds Ag receptor of B or T cell

Question 6

Epitope

Answer 6

Specific region exposed on surface of Ag
Specifically binds Ag receptor of B or T cell

Question 7

Self-Tolerance (Adaptive Immunity)

Answer 7

Depends on ability to distinguish self from non-self
Possible b/c individuals are biochemically unique

Question 8

B and T cell Diversity

Answer 8

Many different B and T cell Ag receptors are generated via genetic recombination and deletion when cells are activated. SPECIFIC

Question 9

Proliferation of B and T Cells

Answer 9

Once activated, multiple cell divisions-> many identical cells

Can become…
Effector cells
Memory cells

Question 10

What are effector cells?

Answer 10

Short lived, work immediately against Ag, any pathogen producing Ag
- Plasma cells, helper T cells, cytotoxic T cells

Question 11

What are memory cells?

Answer 11

Long lived, ready to divide if Ag reappears

Question 12

Clonal Selection

Answer 12

Cell proliferation based on use

Question 13

Immunological Memory

Answer 13

Long-term protection, result of prior infections

Question 14

Primary Immune Response

Answer 14

Response to 1st exposure to Ag

Question 15

Secondary Immune Response

Answer 15

Exposed to same Ag, respond faster- 2-7 days
Stronger, more prolonged

Question 16

B cells and T cells are types of what?

Answer 16

Lymphocytes

Question 17

B cells components

Answer 17

Membranes contain Y-shaped receptors
4 polypeptides
2 heavy chains
2 light chains
Constant (C) region
Variable (V) region

Question 18

B cell Activation

Answer 18

No pathogen- inactive
Ag binds receptor
-> Cells secrete soluble form
= Antibody (Ab)
= Immunoglobulin (Ig)

Question 19

T Cells Overview

Answer 19

Also have Ag receptors with 2 parts
Alpha and Beta chains
V and C regions

Question 20

T cell Ag Receptors

Answer 20

Only bind Ag fragments on surface of host cell
Ag fragments displayed by
- Pathogen-detecting cells
- Infected cells

Question 21

What are the 2 general responses in adaptive immunity?

Answer 21

Humoral Response and Cell-mediated Response

Question 22

Humoral Response

Answer 22

Via antibodies in blood, lymph (B cells)

Question 23

Cell-mediated Response

Answer 23

Infected host cells destroyed by specialized T cells (cytotoxic T cells)

Question 24

Antigen Presenting Cell (APC)

Answer 24

Can be infected or specialized for detection
Presents antigen fragment

Question 25

Helper T Cells

Answer 25

T cell with specific receptor bind APC Ag fragment -> T cell activated via cytokines Autocrine and paracrine signals Positive feedback

Question 26

Once active, helper T cells activate...

Answer 26

B cells- Humoral immunity Cytotoxic T cells- Cell-mediated immunity

Question 27

Cytotoxic T cells

Answer 27

Cell-mediated response Use toxic proteins to kill infected cells before pathogens mature Activated by... - Signals from helper T cells - Interactions with APC- bind Ag fragment

Question 28

Activated Cytotoxic T cells release what?

Answer 28

Perforin: Forms pores Granzymes: Initiate apoptosis -> Infected cell dies, T cell moves on

Question 29

B cells & Antibodies

Answer 29

Humoral response B cell activated by helper T cell Produces Memory B cells and plasma cells Plasma cells secrete antibodies

Question 30

Antibody Functions

Answer 30

DO NOT kill pathogen directly 3 mechanisms - Neutralization - Opsonization - Complement System

Question 31

Neutralization

Answer 31

One function of antibody- Binds virus, interferes with activity

Question 32

Opsonization

Answer 32

One function of antibody- Binds bacteria, promotes phagocytosis

Question 33

Complement System

Answer 33

One function of antibody- Antibody binds Ag on foreign cell Complement protein binds Ab-Ag complex Produces membrane attack complex- pores in PM Water, ions rush in-> lysis

Question 34

Vaccines

Answer 34

Harmless variant or derivative of a pathogen that stimulates adaptive immune response

Question 35

How do vaccines work?

Answer 35

Stimulate primary immune response Pathogen triggers secondary response-> No illness

Question 36

Live attenuated vaccine

Answer 36

Live but weakened, avirulent form of pathogen (cannot cause sickness)

Question 37

Inactivated vaccine

Answer 37

Whole pathogen, killed (by heat or chemicals)

Question 38

Subunit vaccine

Answer 38

Only part of pathogen (antigen containing epitope)

Question 39

DNA/mRNA

Answer 39

DNA/mRNA containing gene for antigen, expressed within vaccinated individual

Question 40

Antigenic Drift

Answer 40

Small changes in viral antigens due to mutation

Question 41

Antigenic Shift

Answer 41

Major changes in vial antigens due to reassortment/recombination

Question 42

Strain Replacement

Answer 42

Replacement of a common strain with a less common one Often due to successful vaccination against common strain

Question 43

Herd Immunity

Answer 43

Vaccinate enough of population so that disease cannot spread R: Transmission rate Goal: R<1 Infected individual transmits to <1 person on average Protects unvaccinated

Question 44

Sequence the activation of the adaptive immune response.

Answer 44

1. APC operates 2. Helper T cells detect antigen 3. B cells activated 4. Antibodies released 5. Reinfection triggers secondary response