Cells and Organs of the Adaptive Immune System

Question 1

list and describe 2 characteristics of the adaptive/acquired immune response

Answer 1

1. specificity: tailored response to increase effectiveness
2. memory: increased speed of and more robust response

Question 2

list and give 2 examples each of the 2 types of specialized cells of the adaptive immune system

Answer 2

1. lymphocytes: B and T cells
2. antigen presenting cells: monocytes (become macrophages) and dendritic cells

Question 3

where are the cells of the adaptive immune response born and matured?

Answer 3

primary lymphoid organs: either the bone marrow (of bursa of fabricius) or the thymus

Question 4

where do the cells of the adaptive immune system work?

Answer 4

secondary lymphoid organs

Question 5

what are 3 secondary lymphoid organs? (just give 3 examples here)

Answer 5

1. lymphatics and lymph nodes
2. spleen
3. MALTs: mucosa-associated lymphatic tissues

Question 6

what are primary lymphoid organs? describe

Answer 6

specialized organs where lymphocytes are formed and mature; and where B and T cells acquire their specific antigen receptor (like school)

Question 7

what are secondary lymphoid organs? describe

Answer 7

organs and tissues where mature lymphocytes are maintained; and where adaptive immune responses are initiated (like work)

Question 8

where do all immune cells originate from?

Answer 8

bone marrow!

Question 9

what is the bone marrow?

Answer 9

the medulla of long bones and some irregular bones like the pelvis and ribs

Question 10

what is in yellow bone marrow?

Answer 10

mostly fat; not relevant to immune system

Question 11

what happens in red bone marrow?

Answer 11

hematopoiesis (generation of red and white blood cells)

Question 12

what gives rise to all blood cells?

Answer 12

hematopoietic stem cells in red bone marrow

Question 13

what causes the distribution of red bone marrow to vary?

Answer 13

species and age

Question 14

what is the big daddy of all hematopoietic cells?

Answer 14

the pluripotent hematopoietic stem cell; could literally become ANY blood cell

Question 15

what 2 cells can pluripotent hematopoietic stem cells differentiate into (that give rise to all others)

Answer 15

either common lymphoid progenitor cells or common myeloid progenitor cells

Question 16

what do all T cells, B cells, and NK cells arise from?

Answer 16

common lymphoid progenitor cells

Question 17

describe B cells that exit the bone marrow

Answer 17

naive (not exposed to antigen of interest) but mature (would know what to do when encounter antigen for first time)

Question 18

once mature, naive B cells exit the bone marrow, where do they go? what do they do there?

Answer 18

travel the secondary lymphoid organs to participate in immune responses by differentiating into antibody-producing plasma cells

Question 19

what happens to B cells as they mature?

Answer 19

they acquire their B cell receptor

Question 20

describe the B cell receptor

Answer 20

located on the surface of the B cell; is a co-receptor complex so in order to stimulate a response, an antigen must bind to both the BCR and have costimulating components

Question 21

what do B cell receptors (BCRs) do for B cells?

Answer 21

confer specificity to recognize and response to non-self antigen

Question 22

how do B cells recognize antigen? contrast to T cells

Answer 22

B cells recognize antigen in NATIVE form!! just as they enter the body; but T cells recognize linear peptides presented by APCs and other cells

Question 23

describe B cell activation

Answer 23

naive B cells bind antigen and multiply in a process called clonal expansion, where the daughter cells have the same BCR as the parent, resulting in many plasma cells able to recognize the same antigen

Question 24

what are mature, activated B cells called?

Answer 24

plasma cells; also called professional cells that secrete antibodies

Question 25

where are plasma cells located?

Answer 25

various lymphoid organs

Question 26

describe T cell maturation

Answer 26

born in bone marrow, but must exit bone marrow and travel to thymus to differentiate into thymocytes; then exit the thymus as mature, naive T cells

Question 27

once they exit the thymus, where do mature, naive T cells go? what do they do?

Answer 27

travel to secondary lymphoid organs to participate in immune responses and differentiate into effector cells

Question 28

compare the thymus in younger animals to older animals

Answer 28

thymus much larger in younger animals than older animals

Question 29

describe the more detailed process of birth and maturation of T cells in the thymus (3)

Answer 29

1. lymphoid progenitors from the bone marrow seed cortex, or thymocytes, interact with epithelial cells in the cortex of the thymus
2. these thymocytes mature as they move toward the medulla of the thymus, where they interact with medullary epithelial cells, macrophages, and dendritic cells
3. then exit the thymus as mature, naive T cells

Question 30

what do T cells gain as they mature?

Answer 30

their T cell receptor (TCR)

Question 31

describe the TCR

Answer 31

located on the surface of the T cell, confers specificity to help immune system distinguish between self and non-self and recognize and respond to non-self antigen

Question 32

describe T lymphocyte activation

Answer 32

T cells bind antigen, multiply a lot in a process called clonal expansion, where daughter cells have the same TCR as parent, resulting in many cells able to recognize the antigen

Question 33

where are activated T lymphocytes found?

Answer 33

various lymphoid organs

Question 34

what are the 2 responses/processes of the adaptive immune system? what cell is involved in each?

Answer 34

1. cell-mediated: T cells
2. humoral: B cells

Question 35

describe cell-mediated adaptive immunity (3)

Answer 35

1. T lymphocytes target intracellular pathogens like viruses
2. cytotoxic (CD8) T cells directly kill infected cells
3. helper (CD4) T cells produce cytokines, activate humoral immunity and innate immune cells (conductors of adaptive response)

Question 36

describe humoral adaptive immunity

Answer 36

B lymphocytes (plasma cells once activated) produce antibodies that can help destroy pathogens like extracellular bacteria, toxins, and viruses