Immunology Review

Question 1

What is CD2? What cells have it?

Answer 1

It’s LFA-3 - an adhesion molecule that’s part of the TCR and facilitates co-stimulation
On Th, Tc and NK cells

Question 2

What cells have CD3 and what does it do?

Answer 2

Th and Tc cells - it’s part of the TCR and provides downstream signalling

Question 3

What is CD16? What cells have it? What does it do?

Answer 3

It’s Fc-gamma-RIII
present on NK cells
it causes antibody dependent cell-mediated cytotoxicity

Question 4

What is CD21 a receptor for? On what cells?

Answer 4

It’s the CR2 complement receptor for c3d - on B cells

Question 5

What cells have CD28?

Answer 5

T cells (binds B7 for costimulation)

Question 6

What is CD32 and what cells have it?

Answer 6

If’s the Fc-gamma-RII on B cells

Question 7

What are the two forms of CD32 and what do they do?

Answer 7

a and b
a is first - it tells B cells to undergo phagocytosis
b is next - it tells the B cells to STOP phagocytosis and become a memory cell

Question 8

What is CD35 a receptor for?

Answer 8

It’s the CR1 complement receptor for Cb3 on B cells

Question 9

What cells have CD40?

Answer 9

B cells (Th cells have the CD40 ligand)

Question 10

Why is the lymph node considered the most specialized secondary lymphoid organ?

Answer 10

it’s totally devoted to making an adaptive immune response

Question 11

Where are the naive T cells located in the LN? Naive B cells?

Answer 11

T cells are in the cortex and the B cells are in the follicles

Question 12

On average, how long are naive lymphocytes in the LNs if they don’t find antigen they like? How about if they DO find antigen

Answer 12

about 18 hours

days

Question 13

If a B cell is activated with antigen and then receives help from a CD4+ cell, what are it’s two options?

Answer 13

It can differentiate to a plasma cell and exit into the circulation to immediately start pumping out IgG

or It can go back to the follicles and form a germinal center to make more B cells with that antigen specificity

Question 14

What additional step happens to the B cells in the germinal centers?

Answer 14

somatic hypermutation (with the help of AID)

Question 15

How does the spleen differ from lymph nodes and how does this determine what it’s used for?

Answer 15

Unlike the LNs, the spleen is only connected to circulation, not lymphatics
this means it’s specialized to filter antigen out of the blood instead of tissue

Question 16

Children without spleens have a particuliarly hard time fighting off what kind of infection?

Answer 16

encapsulated bacterial infections in the blood

Question 17

After leaving the thymus and bone marrow, how long does it take for mature lymphocytes to travel the body?

Answer 17

30 minutes

Question 18

After those 30 minutes, what percentage of lymphocytes will be int he spleen, the lymph nodes, and the MALT?

Answer 18

45% in the spleen
45% in the lymph nodes
10% in the MALT

Question 19

How do the lymph nodes leave circulation to enter lymph nodes?

Answer 19

through HEVs

Question 20

What kind of cells do the naive T cells interact with in thelymph nodes? primarily…

Answer 20

fibroblast cells and dendritic cells

Question 21

What kind of cell do the naive B cells interact with in the lymph nodes?

Answer 21

follicular dendritic cells

Question 22

What are the stages of T cell and APC interactions?

Answer 22

stage 1: stochastic contacts - just tasting
stage 2: transient interactions (1-3 hours)
stage 3: T-cell clusters form (3-16 hours)
stage 4: T cell swarms (16-24 hours)
stage 5: T cell proliferation (over 24 hours)

Question 23

How does antigen delivery to T cells differ from antigen delivery to B cells?

Answer 23

T cells need antigen presented on MHC, so they have to come from an APC
B cells can interact with soluble antigen via the BCR or complement-bound antigen via CD21 when there’s IgG already involved

Question 24

What cell do the B cells “pass” the antigen onto in the latter situation from the previous card?

Answer 24

the follicular dendritic cells, which will then pass it on to a B cell that has antigen specificity for the antigen

Question 25

During somatic hypermutation in the germinal centers, what happens to the B cells if their receptor lessens in affinity for the antigen?

Answer 25

it happens often - remember SHM is random

they undergo apoptosis