introduction to immunology

Question 1

Types of Lueckocytes

Answer 1

1- Lymphoid cells ( T, B and Nk)
2- Myeloid cells ( macrophage, neutrophils and platelets, basophils, monocytess and phagocytes)

Question 2

properties of adaptive immunity

Answer 2

Specificity and diversity
Memory
Clonal expansion
specialization
contraction and homeostasis
Nonreactivity to self

Question 3

Cells of adaptive immunity

Answer 3

1- T and B cells
2- APC
3- Effector cells ( T cells, macrophages and granulocytes)

Question 4

Where do B lymphocytes mature?

Answer 4

In the bone marrow

Question 5

Where do T lymphocytes mature?

Answer 5

In the thymus

Question 6

What are the generative (or central) lymphoid organs?

Answer 6

Sites where mature lymphocytes are produced

Question 7

What happens to mature lymphocytes after leaving the generative lymphoid organs?

Answer 7

They enter circulation and peripheral (secondary) lymphoid organs

Question 8

What is the major site of immune responses?

Answer 8

Peripheral (secondary) lymphoid organs

Question 9

What are effector lymphocytes?

Answer 9

Differentiated progeny of naive cells that can eliminate antigens

Question 10

What are plasma cells?

Answer 10

Antibody-secreting cells developed from B lymphocytes in response to antigenic stimulation

Question 11

What are plasmablasts?

Answer 11

Antibody-secreting cells found in the blood that can migrate to the bone marrow

Question 12

What is the function of cytokines produced by effector CD4+ T cells?

Answer 12

Activate B cells, macrophages, and other cell types

Question 13

What do effector CD8+ T cells do?

Answer 13

Kill infected host cells

Question 14

What happens to effector cells as the antigen is eliminated?

Answer 14

They are short-lived and die

Question 15

What are memory cells?

Answer 15

Cells that can survive long periods in the absence of antigen

Question 16

How does the frequency of memory cells change with age?

Answer 16

It increases due to exposure to environmental microbes

Question 17

What are the common portals of entry for microbes?

Answer 17

Skin, gastrointestinal, respiratory, and genitourinary tracts

Question 18

Which cells are the most specialized antigen-presenting cells in the immune system?

Answer 18

Dendritic cells

Question 19

What role do dendritic cells play in the immune response?

Answer 19

Dendritic cells capture protein antigens of microbes, transport them to lymph nodes, and display fragments for T lymphocyte recognition.

They are crucial for initiating T cell responses.

Question 20

How do dendritic cells present antigens to T lymphocytes?

Answer 20

They capture antigens and display protein fragments in regional lymph nodes for recognition by T lymphocytes.

This process is essential for T cell activation.

Question 21

What types of cells can capture microbes or their antigens in lymphoid organs?

Answer 21

Dendritic cells and macrophages.

These cells reside in lymphoid organs and present antigens to lymphocytes.

Question 22

What are costimulators in the context of T cell activation?

Answer 22

Surface proteins produced by dendritic cells that are required, along with antigen, to activate naive T lymphocytes.

They enhance the effectiveness of T cell responses.

Question 23

Why are dendritic cells considered the most potent stimulators of naive T cells?

Answer 23

They express higher levels of costimulatory proteins than other cell types.

This makes them efficient initiators of T cell responses.

Question 24

How do B lymphocytes recognize antigens?

Answer 24

B lymphocytes may directly recognize antigens of microbes, either released or on their surface.

This is a key aspect of humoral immunity.

Question 25

What role do follicular dendritic cells (FDCs) play in the immune response?

Answer 25

FDCs reside in germinal centers and display antigens that stimulate the differentiation of B cells. ## Footnote They are distinct from dendritic cells that present antigens to T cells.

Question 26

True or False: Follicular dendritic cells present antigens to T cells.

Answer 26

False. ## Footnote FDCs do not interact with T cells; they specifically stimulate B cell differentiation.

Question 27

Fill in the blank: Dendritic cells are the most efficient initiators of _______.

Answer 27

T cell responses. ## Footnote This is due to their unique ability to present antigens and provide costimulatory signals.

Question 28

What are the two main types of lymphoid organs in the immune system?

Answer 28

The two main types of lymphoid organs are generative lymphoid organs and peripheral lymphoid organs.

Question 29

What is the role of generative lymphoid organs?

Answer 29

Generative lymphoid organs are where T and B lymphocytes mature and become competent to respond to antigens.

Question 30

What is the function of peripheral lymphoid organs?

Answer 30

Peripheral lymphoid organs initiate adaptive immune responses to microbes.

Question 31

What are the major peripheral lymphoid organs?

Answer 31

The major peripheral lymphoid organs include lymph nodes, the spleen, and the mucosal and cutaneous immune systems.

Question 32

How do peripheral lymphoid organs promote immune responses?

Answer 32

They are organized to enable antigen-presenting cells (APCs) to concentrate antigens and help lymphocytes locate and respond to them.

Question 33

What is the primary function of lymph nodes?

Answer 33

Lymph nodes sample antigens from lymph and help lymphocytes respond to these antigens.

Question 34

What is the role of the spleen in the immune system?

Answer 34

The spleen captures and concentrates blood-borne antigens, similar to the role of lymph nodes for lymph-borne antigens.

Question 35

What are mucosal and cutaneous immune systems?

Answer 35

They are specialized collections of lymphoid tissues and APCs located in and under the epithelia of the skin and the gastrointestinal and respiratory tracts.

Question 36

What are tonsils and Peyer patches?

Answer 36

Tonsils in the pharynx and Peyer patches in the intestine are examples of anatomically defined mucosal lymphoid tissues.

Question 37

What is a germinal center?

Answer 37

A germinal center is a lightly staining region in a follicle that plays an important role in the production of highly effective antibodies.

Question 38

How are T and B lymphocytes organized in lymph nodes?

Answer 38

B lymphocytes are concentrated in follicles around the cortex, while T lymphocytes are located in the paracortex.

Question 39

What attracts B lymphocytes to follicles?

Answer 39

B lymphocytes are attracted to follicles by chemokines secreted by follicular dendritic cells (FDCs).

Question 40

What chemokine receptor do naive T lymphocytes express?

Answer 40

CCR7

Question 41

What is the role of CCR7 in naive T lymphocyte migration?

Answer 41

It recognizes chemokines produced in the paracortex of lymph nodes and periarteriolar lymphoid sheaths of the spleen

Question 42

What happens to B cells and T cells after they are activated by antigens?

Answer 42

They migrate toward each other and meet at the edge of follicles

Question 43

How do effector T cells exit lymph nodes?

Answer 43

Through efferent lymphatic vessels

Question 44

Where do activated T cells go after leaving lymphoid organs?

Answer 44

They end up in the circulation and can go to distant sites of infection

Question 45

What are high endothelial venules (HEVs)?

Answer 45

Specialized postcapillary venules that naive T lymphocytes use to enter lymph nodes

Question 46

What chemokine receptor do naive B cells express?

Answer 46

CXCR5

Question 47

What is the fate of naive cells that do not encounter specific antigens in lymph nodes?

Answer 47

They leave the lymph nodes and reenter the circulation

Question 48

What do effector T cells preferentially migrate to?

Answer 48

Tissues infected by microbes

Question 49

Where do most antibody-secreting plasma cells migrate to?

Answer 49

The bone marrow or mucosal tissues

Question 50

True or False: The spleen contains high endothelial venules (HEVs).

Answer 50

False