Lymphocyte Activation

Question 1

Which T cell receptors transduce signals

Answer 1

CD3 and zeta-zeta (TcR cannot transduce signals)

Question 2

Which part of B cell receptor serve as signaling molecules once cell engages antigen?

Answer 2

Igα and Igβ

Question 3

Initiate early stages of lymphocyte activation by phosphorylation

Answer 3

ITAM (immunorecetpro tyrosine based activation motifs)

Question 4

Where are ITAMs located?

Answer 4

Cytoplasmic portion of CD3/zeta zeta (T cells) and Igα/ Igβ (B cells)

Question 5

Location of B and T cell interaction

Answer 5

lymph node

Question 6

Lymph node is (secondary/primary) lymphatic tissue

Answer 6

secondary

Question 7

B-cells in lymph node are found in

Answer 7

follicles

Question 8

T cells in lymph node are found in

Answer 8

parafollicular zone (outside of follicles)

Question 9

For B-cell initiation, how are antigen brought into lymph nodes?

Answer 9

By lymphatic drain

Question 10

This cell binds native antigen on its membrane surface for B-cell to bind

Answer 10

Follicular-dendritic cell

Question 11

How do appropriate T-cells and B-cells interact?

Answer 11

MHCII presentation on B cell; T cell activated by presence of antigen on MHC II

Question 12

IL-2 receptor

Answer 12

receptor made by T cells in naive state

Question 13

low affinity IL-2 receptor

Answer 13

Beta and common gamma chain

Question 14

IL-2

Answer 14

IL-2 synthesized BY T CELL after early stages of interaction will induce creation of alpha chain on receptor. Higher affinity leads to cell division and activation

Question 15

inducible factors during APC - Tcell interaction

Answer 15

B7 (on APC/Bcell) and CD40L (Th)

Question 16

CD40L: Where found? Interacts with what?

Answer 16

upregulated on activate T-helper cells, interacts with CD40 on B cells and APCs

Question 17

CD40L fundamental for induction of

Answer 17

AID (for somatic hypermutation of B cells)

Question 18

membrane immunoglobins cross-link through presence of

Answer 18

antigen and ITAMs of BCR (phosphorylated to recruit signaling molecules)

Question 19

How are membrane IgM and IgD assembled with the B cell receptor complex?

Answer 19

non-covalently

Question 20

CD40

Answer 20

expressed by B-cells and APCs, interact with induced CD40L on T helper cell

Question 21

CTLA-4

Answer 21

blocks CD28 and interacts with B7 on B cell. Has higher affinity than CD28, inhibits cell from further activation

Question 22

Used in autoimmune diseases and auto sensitivity designed to block interaction of B7 to T cells

Answer 22

CTLA-4

Question 23

What are examples of T independent responses regarding B cell activation?

Answer 23

Polysaccharides, lipids, and non protein antigens tend to be T-independent

Question 24

Upon receiving B cell growth factors and differentiation factors from T cells, B cells can undergo

Answer 24

expansion and differentiation (antibody producing cells)

Question 25

What initiate interactions of T cells and APCs?

Answer 25

Cell adhesion molecules (Selectins, vascular addressins, integrins, and immunoglobulin superfamily members)

Question 26

what begins T cell activation?

Answer 26

T-cell receptor engages a specific MHC-peptide complex

Question 27

T regulatory cell's key cyotkine

Answer 27

TGF-B

Question 28

function of T regulatory cell

Answer 28

inhibit immune response

Question 29

A major co-stimulation signal

Answer 29

CD28 (on surface of naive T cell) and B7 (on professional APC)

Question 30

Activation of IL-2 gene uses signals delivered from which two things?

Answer 30

TcR and CD28 molecules

Question 31

Following activation, T cells udnergo a rapid phase of cell division under control of which cytokine?

Answer 31

IL-2; self synthesized and created by T cell, thus controlling their own proliferation

Question 32

IL-5

Answer 32

can be made by Th2 for eosinophil activation

Question 33

How does B cell take in a little antigen?

Answer 33

Pinocytosis

Question 34

Migration is crucial for B cell response. Where do B cells migrate to?

Answer 34

margine of the follicle, can communicate directly with T helper cell that will also migrate to that area from otuside

Question 35

ITIMS

Answer 35

inhibiting step (I=inhibitory). If already have antibody against an antigen, soluble antibody bound to antigen can bind to Fc gamma RII. Inhibitory, because don't want to continue activating B cells. = feedback inhibition to shut off B cells

Question 36

Primary lymphoid tissues

Answer 36

Bone marrow and thymus

Question 37

Diagnostic feature of child's thymus; granule cells surrounded by epithelial cells

Answer 37

Hassall's corpuscle

Question 38

A transcription factor that allows expression of tissue specific self-peptides

Answer 38

AIRE (auto immune regulator)

Question 39

Site in thymus for T-cell positive selection

Answer 39

Cortex (immature thymocytes bind MHC)

Question 40

Site in thymus for T-cell negative selection

Answer 40

Medulla

Question 41

What are secondary lymphoid tissue sites and what are some examples

Answer 41

Collection, more organized point for circulating lymphocytes. Spleen (systemic infection), encapsulated lymph nodes (local infection, Peyer's patches (sm intestine)

Question 42

Tertiary lymphoid tissues

Answer 42

MALT (mucous associated lymphoid tissue)-inducible; GALT (large intestine); NALT (nasal); BALT (bronchus)

Question 43

``` specialized post-capillary venous swellings "bag shaped vessel" function is to control selective entry into the lymph nodes( i.e. Naive T cells) ```

Answer 43

High endothelial evnule

Question 44

Which secondary lymphoid tissue lacks HEVs and afferent lypmhatics?

Answer 44

Spleen

Question 45

Red pulp as diagnostic feature

Answer 45

large numbers of CD8 T cells and plasma cells

Question 46

Where do stem cells enter the thymus?

Answer 46

Cortico-medullary junction

Question 47

During involution of the thymus, what replace the functional parenchyma tissue?

Answer 47

CT fibers and fat cells; degenerative process

Question 48

cortical thymic epithelial cells (cTEC) express what in the thymus?

Answer 48

MHC molecules

Question 49

Survivors of positive selection in the thymic cortex move where? (Survivors=TcR bind to MHC molecules, prevent cell-death)

Answer 49

Medulla

Question 50

What do mTEC express? (medullary thymic epithelial cells)

Answer 50

AIRE

Question 51

List four subsets of T cells produced in thymus

Answer 51

1) CD8+ cytotoxic T cells 2) CD4+ helper T cells 3) Regulator T cells (express FOXP3) 4) gamma delta T cells (just know they exist)

Question 52

Mature lymphocytes intearct with other immune cells in primary/secondary/tertiary lymphoid tissues

Answer 52

Secondary

Question 53

B cells and T cells collect in distinct regions of lymph nodes and spleen. What are they?

Answer 53

Within cortex: T cell area = paracortex B cell area = primary follicles (homeostasis), germinal centers (infection)

Question 54

Lymph enters lymph nodes via

Answer 54

Afferent lymphatics (which drain into the capsule)

Question 55

Lymph leaves the peripheral lymph nodes via

Answer 55

Efferent lymphatics (empty into blood at thoracic duct)

Question 56

Dendritic cells pick up antigens in

Answer 56

subapical dome

Question 57

What do peyer's patches lack?

Answer 57

Do not have afferent lymphatics (also are nonencapsulated)

Question 58

3 zones of spleen

Answer 58

Red pulp, white pulp (B and T cell compartments), and perifolliculor zone (surrounds B and T cell zones)

Question 59

What is the marginal zone?

Answer 59

Area in spleen that surrounds the B cell follicles but not the T cell zone

Question 60

Non-selective entry

Answer 60

spleen, due to lack of HEV

Question 61

All lymphocytes enter the spleen via

Answer 61

Marginal zone and red pulp

Question 62

Systemic infection

Answer 62

spleen

Question 63

local infection

Answer 63

peripheral lymph nodes

Question 64

Germinal centers are not present in

Answer 64

thymus (present in spleen, lymph node, and malt)

Question 65

What is the only tissue that contains afferent lymphatics?

Answer 65

Lymph node (not present in thymus, spleen, or MALT)