lecture 2- adaptive immunity

Question 1

define dendritic cell maturation

Answer 1

professional APC’s, can travel from sites of infection to draining lymph nodes and inform B and T cells of what is going on
- go from resting to mature DC’s after exposure to PAMP’s or inflammatory stimuli

Question 2

dendritic cells communicate between the ___ and ___ systems

Answer 2

innate and adaptive

Question 3

location of immature vs mature DC’s

Answer 3

immature: tissue resident
mature: lymph nodes

Question 4

uptake capacity of of immature vs. mature DC’s

Answer 4

immature: highly endocytic and phagocytic
mature: endocytosis shuts down

Question 5

costimulatory molecule expression of immature vs. mature DC’s

Answer 5

immature: low level
mature: high level

Question 6

MHC expression level in immature vs. mature DC’s

Answer 6

immature: low level
mature: high level

Question 7

T cell stimulatory activity in immature vs. mature DC’s

Answer 7

immature: poor stimulators
mature: high stimulators

Question 8

describe infection to immunity process

Answer 8

DC’s pick up, process, and present bacteria into peptides on cell surface- migrate to draining lymph nodes to interact with T cells- clonal expansion, move back to site of infection to kill and clear

Question 9

describe lymph node structure

Answer 9

T and B cells are partitioned into their own zones
- the 2 zones are very close to each other- have communication
- B cell zones called follicles or germinal center

Question 10

primary lymphoid organs are sites at which leukocytes undergo ___ (___) and ___

Answer 10

hematopoiesus (development and differentiation)
selection

Question 11

name primary lymphoid organs

Answer 11

bone marrow & thymus

Question 12

Secondary lymphoid organs are most often the site of T cell and B cell ___

Answer 12

activation

Question 13

describe the receptors of adaptive immunity

Answer 13

• B cell receptor can be expressed on cell surface or secreted (antibody)
  . has 2 identical heavy chains & 2 identical light chains
  . antigen binding site formed by 1 heavy chain variable region and 1 light chain variable region
• T cell receptor always on cell surface (transmembrane)
• B cell has 2 antigen-binding sites, T cell receptor has 1

Question 14

name the 4 life stages of B and T cell

Answer 14

1. formation of a receptor
2. selection
3. activation
4. differentiation

Question 15

describe the life stage of formation of a receptor

Answer 15

Must form a unique highly specific receptor, rearrangement events

Question 16

describe the life stage of selection

Answer 16

-To not recognize self (avoid auto-recognition)
-Selects for T cells, T cells need antigen to be processed and presented by MHC

Question 17

describe life stage of activation

Answer 17

travel out of primary organs to lymph nodes where they constantly search for the signals to activate them

Question 18

describe life stage of differentiation

Answer 18

• B cells can make their antigen presenters better, numerous rounds of proliferation- higher affinity stay, lower don’t
• Memory: proliferation, then contraction and apoptosis of most effectors, a few remain and stay in memory

Question 19

Prior to rearrangement, B cell receptor and TCR genes are said to be in _____. After rearrangement, the DNA of B and T cells is ____

Answer 19

germline configuration
permanently changed

Question 20

gene rearrangment is often referred to as ______, why?

Answer 20

somatic recombination
only happens in somatic cells, not germ cells (sperm and egg)

Question 21

describe T cell diversity- clonal expansion

Answer 21

each T cell has a unique specificity for antigen
- starting “repertoire” of T cells — cell “presenting” antigen for T cells — clonal expansion — effector cells contracted, memory cells stay

Question 22

B cells see _____
T cells see _____

Answer 22

B cells see native antigen through BCR
T cells see antigenic peptides (digested or processed pieces of antigens) presented by MHC molecules

Question 23

what does it take for a T cell to recognize antigens?

Answer 23

antigen processing and presentation
- DC takes up pathogen for degradation, pathogen taken apart inside DC
- pathogen proteins are unfolded and cut into small pieces
- peptides bind to MHC molecules and complexes go to cell surface
- T-cell receptors bind to peptide; MHC complexes on DC surface