Lymphoid Tissues

Question 1

Primary lymphoid tissue

Answer 1

generation of mature, but antigen naive, T and cells
development of antigen recognition
involve rearrangement of antigen receptor genes
ex) bone marrow and thymus

Question 2

Secondary lymphoid tissue

Answer 2

naive lymphocytes reside while waiting to be activated
funnel antigen to antigen specific B and T lymphocytes to drive antigen dependent activation to effector and memory cells
ex) lymph nodes, tonsils, peyer’s patches, spleen

Question 3

Tertiary lymphoid tissue

Answer 3

where elimination of antigen occurs
the battlefield
typically, the tissues have direct contact with external environment
ex) skin, GI tract, lungs, vagina

Question 4

Bone Marrow

Answer 4

has pluripotent stem cells

has stroma

Question 5

B lymphocyte development

Answer 5

earliest B cell precursors located near inner surface of bone, more mature cells are in the axis
immature to mature B cells can take place in secondary lymphoid organs

Question 6

Pluripotent stem cells

Answer 6

differentiate into rbs, lymphocytes, granulocytes, platelets, monocytes

Question 7

stroma

Answer 7

reticular stromal cells, macrophages, adipocytes

provide cell-to-cell contact plus soluble factors

Question 8

thymocytes

Answer 8

differentiate into mature T cells

Question 9

T lymphocyte maturation

Answer 9

originate in bone marrow, but mature in thymus
autoreactive T cells are deleted
mature T cells released into periphery to populate secondary lymphoid tissue
vast majority get killed off

Question 10

thymus

Answer 10

bilaterally symmetrical lobes
after puberty it atrophies
thymocytes migrate from cortex to medulla over several days

Question 11

subcapsular zone of thymus

Answer 11

outside cortex, entrance of prothymocytes

Question 12

hassal’s corpuscles

Answer 12

thymocyte graveyards

Question 13

do T cells undergo apoptosis or necrosis

Answer 13

apoptosis

Question 14

Cortical epithelial cells

Answer 14

provide cell-to-cell contact, cytokines, and peptide hormones

Question 15

Where are lymph nodes located

Answer 15

axillary, inguinal, and cervical regions, and intestinal mesentery

Question 16

Lymphatic vessels

Answer 16

one way valves, giving them uni-directional flow

Question 17

afferent lymphatics

Answer 17

feed lymph nodes

Question 18

efferent lymphatics

Answer 18

transport lymph and cells until convergence with thoracic duct

Question 19

thoracic duct

Answer 19

empties into left subclavian vein

Question 20

primary follicles in cortex of lymph nodes

Answer 20

has resting B cells

Question 21

secondary follicles in cortex of lymph nodes

Answer 21

has antigen-activating B cells

Question 22

germinal centers of cortex of lymph nodes

Answer 22

has proliferating B cells

Question 23

T cell-rich area (paracortex) of lymph nodes houses what

Answer 23

T helper cells

Question 24

Where are dendritic cells located in the lymph node

Answer 24

T cell rich areas

Question 25

Where are macrophages located in the lymph node

Answer 25

marginal sinus and medullary cords

Question 26

what happens to the lymph node if there is little antigen stimulation

Answer 26

few primary follicles and no secondary follicles

Question 27

What happens to the lymph node if there is a lot of antigen stimulation

Answer 27

lots of secondary follilces and may enlarge enough to be palpable

Question 28

high endothelial venules

Answer 28

allow lymphocytes to enter lymph node from the blood

Question 29

How do B cell travel through the lymph node

Answer 29

percolate through T cell rich areas, enhancing the probability that an antigen specific B cell will interact with an antigen specific T cell

Question 30

Spleen

Answer 30

responsible for blood-borne antigens
largest lymphoid tissue
no high endothelial cenules, but has analogous tissue

Question 31

Functions of spleen

Answer 31

remove particulate matter and senescent red blood cells from circulation (in red pulp) and expose lymphocytes to antigens (in white pulp)

Question 32

Peyer’s patches

Answer 32

localized in terminal ileum
B cell follicles surrounded by zone rich in T cells
M cells transport proteins and microbes from intestinal lumen

Question 33

M cells

Answer 33

microfolds on luminal surface

Question 34

Langerhans cells in the skin

Answer 34

sample the environment, can’t activate T cells

Question 35

Langerhans cells

Answer 35

immature dendritic cells present in epidermis
capture and transport antigen to nearest lymph nodes
act as antigen presenting cells to activate T cells

Question 36

langerhans cells in lymph node

Answer 36

mature, can’t ingest, but will activate T cells

Question 37

immune response in a lymph node

Answer 37

antigen transport from tissues to a lymph node
B-cell activation
Germinal center B cells differentiate to plasma cells creating a high affinity antibody

Question 38

Lymphocyte homing

Answer 38

some lymphocytes have a preferred home

dependent on specific “addressins”

Question 39

Lymphocyte recirculation

Answer 39

travel between lymphoid organs
greater probability that rare lymphocytes become activated
recirculation is critical for dispersal of naive and memory cell populations
an individual naive lymphocyte may make a complete circuit 1-2 times a day

Question 40

Memory lymphocytes

Answer 40

have different migration pattern than naive cells

often found in peripheral blood