Cell Mediated Immunity and Humoral Responses I

Question 1

Anergic cell

Answer 1

A cell that no longer responds, can happen to B cells or T cells, is a result of receiving signal 1 w/o signal 2

Question 2

What is the term for the category that CD4 and CD8 are in?

Answer 2

Co-receptors

Question 3

What molecule interacts with B7-1 (CD80) and B7-2 (CD86)?

Answer 3

CD28

Question 4

What is the term for the category that LFA-1 and ICAM-1 are in?

Answer 4

Adhesion molecules

Question 5

What is the term for the category that NFkB, NFAT, and AP-1 are in?

Answer 5

Transcription factors

Question 6

What is the term for the category that anti-TCR, Phytohemagglutinin (PHA) and lipopolysaccharide (LPS) are in?

Answer 6

Polyclonal activators

Question 7

Humoral immunity implies the production of what?

Answer 7

Antibodies

Question 8

What type of cell always expresses B7-1 or B7-2?

Answer 8

Antigen presenting cells

Question 9

Interaction of what two molecules initiates signal 2 in T-cells?

Answer 9

CD28 with either B7-1 or B7-2

Question 10

Signal 1 and Signal 2

Answer 10

Signal 1 - antigenic signal, created by TCR or BCR, Signal 2 - transduction signal, created by co-stimulators

Question 11

What is required for B/T cell activation?

Answer 11

Antigen, co-stimulation, and cytokines

Question 12

ITAM

Answer 12

Immuno-receptor tyrosine-based activation motif

Question 13

What brings antigen to secondary lymphoid organs so T cells can see it?

Answer 13

Dendritic cells or monocytes

Question 14

Alloantigens

Answer 14

Non-self MHCs that can be recognized by T-cells at high rates (1-3 percent of T-cells responding)

Question 15

What percentage of T-cells get activated by alloantigens, superantigens, and polyclonal activators respectively?

Answer 15

Alloantigens - 1 to 3 percent, Superantigens - up to 20 percent, Polyclonal activators - 10 to 100 percent

Question 16

Where are T-cell and B-cell rich zones respectively located?

Answer 16

T-cell rich - paracortical areas of lymph nodes and periarteriolar lymphoid sheath of spleen, B-cell rich - follicles of lymph nodes and spleen

Question 17

What are the co-receptors on T-cells and what do they do?

Answer 17

CD8 and CD4, they help stabilize the interaction of presented antigen

Question 18

In non-immune individuals, what is the frequency of T cells specific for a typical antigen?

Answer 18

Between 1 in 10 to the 5th and 1 in 10 to the 6th

Question 19

What is used for co-stimulation with B-cells?

Answer 19

CD40L (on a helper T-cell) binding to CD40 (on the B-cell)

Question 20

Are costimulators constitutively or transiently present on the surface of cells that provide costimulation?

Answer 20

Transiently (this helps prevent non-specific co-stimulation)

Question 21

What is the less commonly used co-stimulatory receptor on B-cells and what does it bind?

Answer 21

CD21 (CR2), it binds a C3d (which is cleaved from C3b) - coated microbes

Question 22

Follicular B cells

Answer 22

Live in follices of secondary lymphoid organs, require helper T-cell co-stimulation for activation

Question 23

T-independent antigens, define give an example and identify what type of molecule can be a t-independent antigen

Answer 23

Antigens that can activate a B response without T-cell help, generally large molecules with repeating identical subunits, e.g. bacterial polysaccharides, glycolipids and nucleic acids

Question 24

What types of B cells respond to T-independent antigens and where is each type found?

Answer 24

Marginal zone B cells (spleen) and B-1 B cells (peritoneal cavity and mucosal tissues)

Question 25

What type of B response occurs in the case of T-independent antigens

Answer 25

An IgM response, with little or no isotype switching

Question 26

Is a T-independent B-cell response considered high memory or low memory?

Answer 26

Low memory (memory and isotype switching require signals from T-cells)

Question 27

What type of cell uses ITAMs and where do they fall in the process of cell activation?

Answer 27

T-cells. After antigen recognition and signal 1 and 2 are activated, Src Family TKs (such as Lck) phosphorylate ITAMs which then activates two pathways to gene transcription

Question 28

In T-cell and B-cell activation, what are the two major downstream pathways that lead to gene transcription?

Answer 28

The Calcium-NFAT pathway (PLC, IP3, DAG) and the Ras/Rac-MAP kinase pathway

Question 29

What are the three main transcription factors activated in B and T cell activation?

Answer 29

NFAT, NF-KB, and AP-1

Question 30

B-cell activation requires clustering of what and what is the result of this clustering?

Answer 30

2 or more antigen receptors cluster and then tyrosines in the ITAMs of Ig-alpha and Ig-beta are phosphorylated

Question 31

Give the proportion of B cells specific for a given antigen in the case of unimmunized individual, peak response individual, and post response (memory) individual

Answer 31

Unimmunized - 1 in 10 to the 5th or 6th, Peak response - 1 in 10 cells, Post response - 1 in 100 or 1000 cells