Cells and Tissues of the Adaptive Immune System (Lec 2)

Question 1

Naive lymphocytes typically die if they do not recognize an antigen after how long?

Answer 1

1 to 3 months

Question 2

Why are naive and memory lymphocytes both called resting lymphocytes?

Answer 2

they are not actively dividing, nor are they performing effector functions

Question 3

Naive lymphocytes are in a state of rest. Which phase of the cell cycle is this?

Answer 3

G0

Question 4

What does the survival of naive lymphocytes depend on?

Answer 4

Antigen receptors and cytokines

Question 5

True or False?
Naive T lymphocytes (TCR) recognize various self antigens weakly, enough to generate survival signals but without triggering clonal expansion and differentiation into effector cells.

Answer 5

True

Question 6

What is the most important cytokine for survival of naive T cells?

Answer 6

IL-7, promotes low-level cycling of naive T cells

Question 7

True or False?

BAFF is not required for naive B cell survival.

Answer 7

False. It is required

Question 8

True or False?

Cytokines serve as soluble regulatory factors or “messengers” for the immune system

Answer 8

ture

Question 9

Which cytokines play an important role in T cell development?

Answer 9

IL-1,2,6,&7

Question 10

True or False?

Following migration from the thymus, most mature naive T cells are maintained in the periphery without proliferating

Answer 10

True

Question 11

In T cell selection process, highly self-reactive T cells are removed and two different kinds of T cells develop. What are the two kinds of T cells?

Answer 11

T helper cells - express CD4 and provide help for B cell growth and differentiation

Cytotoxic T lymphocytes - express CD8 and recognize and kill virus-infected cells

Question 12

When do B cells start to develop from stem cells?

Answer 12

around the 14th week of gestation

Question 13

Where does differentiation into B cells occur before and after birth?

Answer 13

before birth - fetal liver

after birth - bone marrow

Question 14

Which cytokines play an important role in B cell development?

Answer 14

IL-1,6,&7

note: IL-2 is found in T cell development but not B cell development

Question 15

B cells, when activated by an antigen and with T cell help, proliferate in germinal centers and mature into two types of cells called?

Answer 15

memory cells or plasma cells

Question 16

What do plasma cells do?

Answer 16

produce and secrete large amounts of antibodies

Question 17

True or False?

B cells present antigens to helper T cells

Answer 17

true

Question 18

Where are the only 3 places lymphocytes do not reach?

Answer 18

eye, brain, testicles

Question 19

Lymphocytes reach the intestine via a specialized endothelium of post capillary venues called?

Answer 19

High endothelium venules (HEV)

Question 20

Cells of HEV express high levels of adhesion molecules that serve as _____ for lymphocytes?

Answer 20

homing receptors

Question 21

In response to chemokines, how do lymphocytes migrate into tissue?

Answer 21

by diapedesis

Question 22

How do lymphocytes reenter the circulation?

Answer 22

via efferent lymph vessels that merge into the thoracic duct

Question 23

Where are antigens captured?

Answer 23

from a site of infection and the draining lymph node to which those antigens are transported and where the immune response is initiated

Question 24

What are the steps in lymphocyte activation?

Answer 24

1) naive T cells and immature B cells migrate into secondary lymphoid organs such as lymph nodes and spleen.
2) B cells complete their maturation in LNs and spleen
3) naive B and T cells activated by antigens differentiate into effector or memory lymphocytes
4) some effector and memory lymphocytes migrate into peripheral tissue sites of infection
5) antibodies secreted by effector B cells in LNs, spleen, and bone marrow enter the blood and are delivered to sites of infection

Question 25

What signal do Antigen-presenting cells give?

Answer 25

stimulate the proliferation and differentiation of the lymphocytes

Question 26

True or False? Antigen-presenting cell usually refers to a cell that displays antigen to T lymphocyte because B lymphocytes do not need antigen-presenting cells for their activation.

Answer 26

true

Question 27

What is the major type of APC that is involved in initiating T cell responses?

Answer 27

dendritic cell (DC)

Question 28

True or False? | Macrophages and B cells are not APCs

Answer 28

false. they are both APCs

Question 29

What is the function of the specialized cell type called the follicular DC?

Answer 29

displays antigens to B lymphocytes during particular phases of the humoral immune response

Question 30

DCs and macrophages provide a link between?

Answer 30

innate and adaptive immunity

Question 31

True or False? | DCs have short membranous projections and do not have phagocytic capabilities.

Answer 31

False. DCs have long membranous projections and have phagocytic capabilities

Question 32

Maturation of DCs is dependent on what?

Answer 32

cytokine called Flt3 Ligand note: it binds to the tyrosine kinase receptor on precursor cells

Question 33

True or False? | Macrophages and DCs express receptors that recognize antigens made by mammalian cells, not microbes.

Answer 33

False. Macrophages and DCs express receptors that recognize antigens made by microbes, not by mammalian cells

Question 34

True or False? | Activated DCs also secrete cytokines

Answer 34

true

Question 35

Where are classical DCs found?

Answer 35

skin, mucosa, and organ parenchyma

Question 36

Upon activation by microbes, classical DCs migrate to lymph nodes where they...?

Answer 36

display microbial protein antigens to T lymphocytes

Question 37

True or False | Plasmacytoid DCs are late cellular responders to viral infection.

Answer 37

False. early cellular responders

Question 38

What do plasmacytoid DCs recognize?

Answer 38

nucleic acids of intracellular viruses

Question 39

True or False? | IFN-alpha/beta have potent antiviral activities.

Answer 39

true

Question 40

True or False? | During the inflammatory response in the tissue, DCs may also be derived from circulating monocytes?

Answer 40

true

Question 41

Where do Follicular Dendritic Cells (FDCs) reside?

Answer 41

LNs, spleen, and mucosal lymphoid tissue

Question 42

True or False? | FDCs are unrelated to the DCs that present antigens to T lymphocytes.

Answer 42

true

Question 43

What is the function of FDCs?

Answer 43

bind and display protein antigens on their surfaces for recognition by B lymphocytes

Question 44

FDCs have remarkable ability to...?

Answer 44

retain complement-fixed antigens on their cell surface for extended periods of time

Question 45

Retained immune complexes have long been known to provide...?

Answer 45

antigen stimulus that drives antibody affinity maturation

Question 46

True or False? The effector functions of Innate Lymphoid Cells (ILCs) are similar to those of T cells, but they lack T cell antigen receptors

Answer 46

true

Question 47

What are the major functions of ILCs?

Answer 47

to provide early defense against infectious pathogens to recognize stressed and damaged host cells and help to eliminate these cells to influence the nature of the subsequent adaptive immune response

Question 48

What are the first and best characterized innate lymphoid cells?

Answer 48

natural killer cells

Question 49

What cytokine do NK cells secrete?

Answer 49

IFN-gamma

Question 50

True or False? | Naive T and B lymphocytes migrate to the same areas of a LN

Answer 50

False, they have their own zones and are drawn by chemokines that are produced in these areas

Question 51

True or False? After picking up antigens and entering LN through afferent lymphatic vessels, DCs migrate to the B cell-rich area of the LN.

Answer 51

False, migrate to the T cell-rich area of the LN