Lecture 7

Question 1

Secondary lymphoid organs (aka peripheral)

Answer 1

Lymph nodes

Spleen

Mucosal-associated 
lymphoid tissue (MALT)

Question 2

Primary lymphoid organs (aka generative, central)

Answer 2

Bone Marrow

Thymus

Question 3

GM-CSF

(colony stimulating factor)

Answer 3

cellular source:
T cells, macrophages, endothelial cells, fibroblasts

immature cell target:
Immature and committed myeloid progenitors, mature macrophages

cell’s induced to grow:

Granulocytes and monocytes, macrophage activation

Question 4

M-CSF

Answer 4

cellular source: Macrophages, endothelial cells, bone marrow cells, fibroblasts

cell’s induced to grow: Monocytes

Question 5

IL-3

Answer 5

cellular source: T cells

immature cell targets: Immature progenitors

cell’s induced to grow: All

common cytokine to all progenitors

Question 6

IL-7

Answer 6

source:
fibroblasts, bone marrow, stromal cells

immature cell target: immature lymphoid pregenitors

principal cell populations induced: T lymphocytes

Question 7

Stem cell factor (c-Kit ligand)

Answer 7

source: bone marroe

immature cells: HSC

induce growth in: ALL

Question 8

Bone Marrow - primary organ

The common lymphoid progenitor cell

Answer 8

The common lymphoid progenitor cell is a Precursor to T cells, B cells, and NK cells.

Most of the steps in B cell maturation take place in the bone marrow, but the final events occur after the cells leave the marrow and enter secondary lymphoid organs, particularly the spleen.

Question 9

The common myeloid progenitor cell

Answer 9

The common myeloid progenitor cell
Mature RBCs, platelets, granulocytes (neutrophils, eosinophils, basophils), and monocytes.
Most dendritic cells arise from the monocyte lineage.

innate immunity- mostly stay in the bone marrow

Question 10

primary lymphoid organ= THYMUS

Answer 10

Site of T cell maturation

Flat bilobed organ above the heart

2 compartments

Outer cortex: Immature T cells (thymocytes)

Inner medulla: as thymocytes mature they migrate here

Question 11

THYMUS

Outer cortex:

Answer 11

Immature T cells (thymocytes)

Question 12

(THYMUS)

Inner medulla:

Answer 12

Inner medulla: as thymocytes mature they migrate here

The medulla also contains a network of dendritic cells and macrophages which contribute to T cell development.

Question 13

Where is IL-7 [ ] in the thymus?

Answer 13

Outer cortex, where the immature T-cells are

Thymic cortical epithelial cells secrete IL-7, a growth factor required for early T cell development.

Question 14

Role of Thymic medullary epithelial cells?

Answer 14

Thymic medullary epithelial cells aid in the removal of self-reactive T cells.

Question 15

DiGeorge syndrome

Answer 15

Humans with DiGeorge syndrome suffer from T cell deficiency because of mutations in genes required for thymus development.

Also effects parathyroid gland (resulting in hypocalcemia) and heart development- linked by 3rd pharyngeal pouch origin

Question 16

How does antigen in peripheral tissue concentrate in the lymphoid organs?

Answer 16

The lymphatic system

1. Plasma continually leaks out of the blood vessels and forms extra-cellular fluid (interstitial fluid). Bathes all cells.
2. Much of the fluid is returned to the blood through the walls of the venules.
3. Lymphatic vessels, which originate in the connective tissues throughout the body, drain the remaining fluid (now called lymph) from the tissues.
4. Lymph contains a mixture of substances from the tissues: including debris from dying cells, antigens from infectious organisms, or dendritic cells that have captured antigen and are leaving the tissue as well.

Question 17

Result of Interstitial Fluid Collecting and not Draining to the Lymphatics

Answer 17

Wuchereria bancrofti induced elephantiasis

Question 18

Antigen concentrated in the lymph nodes is presented to the cells of the adaptive immune system. How is this done?

Answer 18

The net result is that antigens of microbes entering through the epithelia or colonizing the tissues become concentrated in the draining lymph nodes.

Collected lymph drains into lymph nodes, small nodular organs, which filter soluble and DC associated antigen before the lymph returns to the blood via the thoracic duct.

Question 19

what exits thru the Efferent lymphatic?

Answer 19

Activated T or B cell- they found their antigen and are now activated or Naieve cell bc it didn’t find its match

Question 20

What are the different areas of the lymph node?

slide 22

Answer 20

1. Afferent lymphatic
2. Paracortical (T-cell)- this is where dendritic cell present what they have to T-cells
3. Primary lymphoid follicle (B cell zone)
4. secondary follicle with germinal center (site of B cell proliferation)
5. Medullary cords (macrophage and plasma cell center)
6. Efferent Lymphatic

Question 21

How do lymphocytes wind up in the correct regions of lymph nodes?

(slide 24)

Answer 21

Chemokines

they make the B-cell go to the B-cell zone on the outside

and T-cell zone on the inside

Question 22

Spleen

Answer 22

T-cell zone–> PALS (periarteriol lymphoic sheath)

B-cell zone = follicle

Question 23

Why spleen important?

Answer 23

The spleen also removes aging and damaged blood cells and particles (such as immune complexes and opsonized microbes) from the circulation.

MACROPHAGES

Question 24

Red Pulp in spleen (slide 26)

Answer 24

Macrophages!!!

Open circulation of the red pulp chords drain into the splenic sinus then vein, which carries blood out of the spleen and into the portal circulation.

**Macrophages here remove microbes (especially opsonized), and old/damaged RBCs

Question 25

What happens when you dont have a spleen?

Answer 25

Individuals lacking a spleen are highly susceptible to infections with *encapsulated bacteria normally cleared by O and P by splenic macs.

Question 26

White Pulp of spleen contains?

Answer 26

Immune cells!

The lymphocyte-rich, white pulp regions are organized around central arteries. Separated from the red pulp by the marginal zone (contain marginal zone B cells).
Site of immune response targeting blood-borne antigens

Question 27

How are the organization of the spleen and the lymph node similar?

Answer 27

Similar to the LNs, the white pulp has segregated T cell and B cell zones:
1. T cells are concentrated in periarteriolar lymphoid sheaths (PALS), surrounding the central arteries.

2. B cells reside in the follicles.