Lecture 13: Adaptive Immunity

Question 1

What is specific immunity?

Answer 1

aka the third line of defense or adaptive immunity

the body’s ability to recognize and defend itself against distinct invaders and their products

A “smart” system whose “memory” allows it to respond rapidly to a second encounter with a pathogen

Question 2

What are the types of specific immunity?

Answer 2

Humoral: antibodies produced by B cells

Cell-mediated: involves T cells

Question 3

What is an antigen (Ag)?

Answer 3

a substance that causes the body to produce specific antibodies or sensitizes T cells (from the invaders)

Question 4

What is an antibody (Ab)?

Answer 4

A protein made in response to an antigen (from the hosts)

Question 5

What is the overview of adaptive immunity?

Answer 5

1. lymphocyte development and differentiation
2. the presentation of antigens
3. the challenge of B and T lymphocytes by antigens
4. B-lymphocyte response (the production and activities of antibodies) and T-lymphocyte response (cell-mediated immunity)

Question 6

What is the lymphatic system?

Answer 6

Screens the tissues for foreign antigens

Composed of lymphatic vessels and lymphatic cells

Question 7

Lymph system vs blood system

Answer 7

see more

Question 8

Lymphatic vessels:

Answer 8

Form a one-way system: conducts lymph from local tissues and returns it to the circulatory system

Question 9

What is lymph?

Answer 9

A liquid:
-similar composition to blood plasma

-arises from fluid leaked from blood vessels into surrounding tissues

Question 10

Lymphatic cells:

Answer 10

From stem cells in bone marrow

Includes lymphocytes, smallest leukocytes

Question 11

What are lymph nodes?

Answer 11

Houses leukocytes that recognize and attack foreign antigens present in the lymph

Concentrated in the cervical (neck), inguinal (groin), axillary (armpit), and abdominal regions

Question 12

Role of spleen as lymphatic organ

Answer 12

Similar in structure and function to the lymph nodes

Filters bacteria, viruses, toxins, and other foreign matter from the blood

Question 13

Role of tonsils and mucosa-associated lymphoid tissue (MALT)

Answer 13

Physically trap foreign particles and microbes

MALT includes the appendix, lymphoid tissue of the respiratory tract, and Peyer’s patches in the wall of the small intestine

Question 14

Discuss B lymphocytes

Answer 14

Arise and mature in the red bone marrow

Found primarily in the spleen, lymph nodes, red bone marrow, and Peyer’s patches

Small percentage of B cells circulate in the blood

Major function is the secretion of antibodies

Question 15

Discuss antibodies

Answer 15

Also called immunoglobulins (Ig)

Soluble, proteinaceous molecules that bind antigen

Secreted by plasma cells which are B cells actively fighting exogenous antigen

Part of the humoral immune response

Question 16

Discuss T lymphocytes

Answer 16

Produced in the red bone marrow and mature in the thymus

Circulate in lymph and blood to lymph nodes, spleen, and Peyer’s patches

Part of the cell-mediated immune response, act directly against antigens:
-endogenous invaders
-many of the body’s cells that harbor intracellular pathogens

Question 16

What are the ways that antibodies function?

Answer 16

Activation of complement

Stimulation of inflammation

Agglutination

Neutralization

Opsonization

Antibody-dependent cell-mediated cytotoxicity

Question 17

Discuss antigens

Answer 17

Molecules that trigger a specific immune response
-components of bacterial cell walls, capsules, pili, and flagella
-proteins of viruses, fungi, and protozoa

Contain antigenic determinants (epitope)

Food and dust can also contain antigenic particles

Question 18

What are the ways antigens can enter the body?

Answer 18

Through breaks in the skin and mucous membranes

Direct injection, as with a bite or needle

Through organ transplants and skin grafts

Question 19

Discuss antigenic determinants

Answer 19

Parts of an antigen

Antibodies recognize and react with antigenic determinants or epitopes

Question 20

Haptens

Answer 20

Small separable parts of an antigen

must specifically bind to an antibody to stimulate antibody production

Question 20

Which T cell type is mainly responsible for interaction with B cells?

Answer 20

T helper cell 2 (TH2)

T cell type mainly responsible for interaction with B cells:

Drives B-cell proliferation; secretes IL-4, IL-5, IL-13

Question 20

Which T cell type is mainly responsible for inflammation promotion?

Answer 20

T helper cell 17 (TH17)
Promotes inflammation; secretes IL-17; important in lung immunity

Question 20

Which T cell type is mainly responsible for cell-mediated pathway?

Answer 20

T helper cell 1 (TH1)
Activates the cell-mediated immunity pathway;
secretes tumor necrosis factor and interferon gamma;
also responsible for delayed hypersensitivity (allergy occurring several hours or days after contact)

Question 21

Which T cell type is mainly responsible for prevention of autoimmunity?

Answer 21

T regulatory cell (TR)
Controls specific immune response
Prevents autoimmunity

Question 22

Which T cell type is mainly responsible for foreign cell lysis?

Answer 22

T cytotoxic cell (TC)

Destroys a target foreign cell by lysis

Important in destruction of complex microbes, cancer cells, virus-infected cells

Graft rejection

Requires MHC-1 for activation

Question 23

What do memory T cells do? How are they formed?

Answer 23

Differentiate after activation of T helper or T cytotoxic cell
Do not participate in initial response but seed immune tissues to be activated in future responses
Always bear receptors for the specific antigen that originally activated TH or TC cell from which they are derived

Question 24

What are on the surface of B cells and T cells?

Answer 24

B cells:
Immunoglobulin; B-cell receptor; MHC II marker

T cells:
Distinct CD molecules: CD3, CD4/ CD8; T-cell receptor

Question 25

What are antibodies?

Answer 25

Also called immunoglobulins (Ig)
Soluble, proteinaceous molecules that bind antigen
Secreted by plasma cells, which are B cells actively fighting exogenous antigen
Part of the humoral immune response

Question 26

Antibody function: Activation of complement:

Answer 26

The interaction of an antibody with complement can result in the specific rupturing of cells and some viruses

Question 27

Antibody function: Agglutination

Answer 27

The capacity of antibodies to aggregate, or agglutinate, antigens is the consequence of their cross linking cells or particles into large clumps. Agglutination renders microbes immobile and enhances their phagocytosis.

Question 28

Antibody function: Neutralization

Answer 28

In neutralization reactions, antibodies fill the surface receptors on a virus or the active site on a microbial enzyme to prevent it from attaching normally

Question 29

Antibody function: Opsonization

Answer 29

When antibodies bind to microbes, they encourage the uptake of the microbe by phagocytes. Opsonization has been likened to putting handles on a slippery object to provide phagocytes a better grip.

Question 30

What are the different types of antigens?

Answer 30

Antigenic determinants
Exogenous antigens
Endogenous antigens
Autoantigens

Question 31

Clonal Deletion:

Answer 31

The process of destroying B and T cells that react to self antigens

Question 32

Immune Tolerance:

Answer 32

When lymphocytes develop a harmful specificity for self molecules, they are eliminated from the pool of cells

Question 33

Clonal Selection of B cells:

Answer 33

Bone marrow gives rise to B cells
Mature B cells migrate to lymphoid organs
A mature B cells recognizes epitopes by B-cell receptors

Question 34

What are the requirements for effective vaccines? If one requirement is not met, should the vaccine be used? Why or why not?

Answer 34

It should have a low level of adverse side effects or toxicity and not cause serious harm
It should protect against exposure to natural, wild forms of pathogen
It should stimulate both antibody (B-cell) response and cell-mediated (T-cell) response
It should have long-term, lasting effects (produce memory)
It should not require numerous doses or boosters
It should be inexpensive, have a relatively long shelf life, and be easy to administer.

Question 35

Advantages and disadvantages of live, attenuated vaccines?

Answer 35

Advantages:
Viable organisms can multiply and produce infection but not disease
Confer long-lasting protection
Require fewer disease and boosters
Effective at inducing cell-mediated immunity

Disadvantages:
Require storage facilities
Can be transmitted to other people
Can mutate to become virulent again

Question 36

How are DNA vaccines made?

Answer 36

DNA that codes for protein antigen is extracted from pathogen genome

Genomic DNA is inserted into plasmid vector; plasmid is amplified and prepared as vaccine

DNA vaccine is injected into subject

Cells of subject accept plasmid with pathogen’s DNA, DNA is transcribed and translated into various proteins

Foreign protein of pathogen is inserted into cell membrane, where it will stimulate immune response.