Lecture 2

Question 0

Why do lymphocytes enter G1 phase?

Answer 0

d/t stimulation, they are activated lymphocytes called large lymphocytes of lymphoblasts

Question 1

What lymphocytes are in the G0 phase?

Answer 1

Naive and Memory cells- resting lymphocytes. Not actively dividing or performing effector functions.

Question 2

Survival of naive Lymphocytes depends on what?

Answer 2

Signals generated by Antigen receptors TCR or BCR or Cytokines

Question 3

How to antigen receptors of naive BCR’s survive?

Answer 3

They generate survival signals even in the absence of antigen

Question 4

How do naive TCR receptors survive?

Answer 4

Naive TCR recognize self antigens weakly enough to generate survival signals but without triggering clonal expansion and differentiation into effector cells.

Question 5

What is the most important cytokine for naive T cell survival?

Answer 5

IL-7 promotes low level cycling of naive T cells

Question 6

What cytokine belonging to the TNF family is required for B cell survival?

Answer 6

BAFF- B cell activating factor

Question 7

The cell to cell interaction of T cells with specialized epithelial cells, DC’s and M0 cell in the thymus provide mechanisms for what?

Answer 7

Selection, and differentiation of T cells useful to the immune system.

Question 8

What are immune system messengers?

Answer 8

Cytokines

Question 9

What Cytokines are important in T cell development?

Answer 9

IL-1,2,6,7

Question 10

Following migration from the Thymus, Naive T Cells-

Answer 10

are maintained in the periphery with out proliferating

Question 11

Where are Antigen specific T cells produced

Answer 11

in the Thymus from circulating T cell precursors derived from stem cells in bone marrow

Question 12

Each T cell has receptor specific for how many antigens?

Answer 12

One- generated by gene rearrangement from multiple inherited germline genes

Question 13

T cells undergo selection to do what?

Answer 13

Remove those that are self reactive

Question 14

T helper cells express what?

What is the function?

Answer 14

Cd4

To provide help for B cell growth and differentiation

Question 15

Cytotoxic T cells express what?

What is it’s function

Answer 15

CD8

To recognize and kill virus infected cells

Question 16

Mature T cells migrate where?

To do what?

Answer 16

To secondary lymphoid tissue

To mediate protection

Question 17

B cell development starts where in the fetus and continues where after birth?

Answer 17

in the fetal liver at 14 weeks gestation and after birth in the bone marrow

Question 18

What cytokines are important for B cell development?

Answer 18

Contact with Stromal cell and IL-1,6,7

Question 19

Where are BCR’s encoded for recognition of antigen?

Answer 19

in bone marrow

Question 20

Do B cells recognize more than one antigen?

Answer 20

No B cells are generated each with a unique specificity for a particular antigen.
BCR’s that react with self antigens are eliminated,

Question 21

B1 and B2 develop with different properties, What is the first Antibody expressed on B cells and what is the second?

Answer 21

IgM is first expressed as the BCR and then IgD.

Question 22

Mature B cells migrate where?

Answer 22

Secondary Lymphoid tissue where they respond to foreign antigens.

Question 23

What happens when B cells are activated by an antigen?

Answer 23

They proliferate in germinal centers and mature into memory and plasma cells. Plasma cells are terminally differentiated B cells which produce and secrete large amounts of antibody

Question 24

How do B and T cells interact?

Answer 24

B cells present antigens to helper T cells which is a key step in cooperation of T helper cells with B cells for antibody responses to protein antigens

Question 25

Lymphocytes circulate everywhere except?

Answer 25

Brain, Eyes, Testicles.

Question 26

HVEC's allow lymphocytes to enter where?

Answer 26

Skin, intestines, and lymph nodes

Question 27

HEV's function to do what?

Answer 27

Express high levels of adhesion molecules that serve as homing receptors for lymphocytes in response to chemokines- lymphocytes migrate by diapedesis into tissue

Question 28

How do lymphocytes reenter circulation?

Answer 28

Via efferent LN's that merge into the thoracic duct

Question 29

Where do naive lymphocytes go?

Answer 29

1. Respond to foreign bodies in secondary lymph tissue | 2. Return by lymphatic drainage and recirculate through other secondary organs

Question 30

What are the steps of lymphocyte activation?

Answer 30

1. Fully mature naive T cells and immature B cells migrate to 2 lymph organs 2. B cells complete maturation in LN and spleen 3. Naive B and T activated by Antigens and differentiate into effector or memory lymphocytes 4. Some effector or memory lymphocytes migrate into peripheral tissue sites of infection 5. Antibodies secreted by effector B cells in LN and spleen and bone marrow enter the blood and are delivered to sites of infection

Question 31

What are APC's

Answer 31

Cells that capture process and display microbial antigens to lymphocytes and provide signals that stimulate the proliferation and differentiation of lymphocytes

Question 32

What cells are considered APC's

Answer 32

Macrophages and B cells present antigens in cell mediated and humoral Dendritic cells- Major APC

Question 33

What type of cell relies on APC's

Answer 33

Mostly T cells, B cells do not need APC for activation

Question 34

Follicular Dendritic Cells display what?

Answer 34

B cells during phases on humoral immunity

Question 35

what provides a link between innate and adaptive immunity?

Answer 35

Dendritic cells and macrophages because they are used in both

Question 36

What do Dendritic cells do and what lineage are they from?

Answer 36

Important for T cell activation, phagocytic capabilities | Derive from myeloid lineage

Question 37

What is dendritic cell maturation dependent on?

Answer 37

FLT3 ligand which binds to FLT3 Tyrosine Kinase receptors on the precursor cells.

Question 38

Activated DC's secrete what?

Answer 38

Cytokine

Question 39

Macrophages and Dendritic cells express receptors that recognize Antigens typically made by what?

Answer 39

Microbes and not mammalian cells

Question 40

Classical DC's reside where?

Answer 40

Skin, Mucosa and organ parenchyma

Question 41

How are Classical DC activated?

Answer 41

By microbes- they migrate to LN's where they display microbial protein antigens to T lymphocytes

Question 42

What is the function of Plasmacytoid DC's

Answer 42

Early responders to viral infections they recognize nucleic acids of intracellular viruses and produce soluble proteins Type I interferons aka IFN alpha/beta that have potent antiviral activities

Question 43

During an inflammatory response DC's may also come from where?

Answer 43

circulating monocytes