Lecture 7 Flashcards
(27 cards)
Secondary lymphoid organs (aka peripheral)
Lymph nodes
Spleen
Mucosal-associated lymphoid tissue (MALT)
Primary lymphoid organs (aka generative, central)
Bone Marrow
Thymus
GM-CSF
(colony stimulating factor)
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
M-CSF
cellular source: Macrophages, endothelial cells, bone marrow cells, fibroblasts
cell’s induced to grow: Monocytes
IL-3
cellular source: T cells
immature cell targets: Immature progenitors
cell’s induced to grow: All
common cytokine to all progenitors
IL-7
source:
fibroblasts, bone marrow, stromal cells
immature cell target: immature lymphoid pregenitors
principal cell populations induced: T lymphocytes
Stem cell factor (c-Kit ligand)
source: bone marroe
immature cells: HSC
induce growth in: ALL
Bone Marrow - primary organ
The common lymphoid progenitor cell
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.
The common myeloid progenitor cell
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
primary lymphoid organ= THYMUS
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
THYMUS
Outer cortex:
Immature T cells (thymocytes)
(THYMUS)
Inner medulla:
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.
Where is IL-7 [ ] in the thymus?
Outer cortex, where the immature T-cells are
Thymic cortical epithelial cells secrete IL-7, a growth factor required for early T cell development.
Role of Thymic medullary epithelial cells?
Thymic medullary epithelial cells aid in the removal of self-reactive T cells.
DiGeorge syndrome
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
How does antigen in peripheral tissue concentrate in the lymphoid organs?
The lymphatic system
- Plasma continually leaks out of the blood vessels and forms extra-cellular fluid (interstitial fluid). Bathes all cells.
- Much of the fluid is returned to the blood through the walls of the venules.
- Lymphatic vessels, which originate in the connective tissues throughout the body, drain the remaining fluid (now called lymph) from the tissues.
- 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.
Result of Interstitial Fluid Collecting and not Draining to the Lymphatics
Wuchereria bancrofti induced elephantiasis
Antigen concentrated in the lymph nodes is presented to the cells of the adaptive immune system. How is this done?
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.
what exits thru the Efferent lymphatic?
Activated T or B cell- they found their antigen and are now activated or Naieve cell bc it didn’t find its match
What are the different areas of the lymph node?
slide 22
- Afferent lymphatic
- Paracortical (T-cell)- this is where dendritic cell present what they have to T-cells
- Primary lymphoid follicle (B cell zone)
- secondary follicle with germinal center (site of B cell proliferation)
- Medullary cords (macrophage and plasma cell center)
- Efferent Lymphatic
How do lymphocytes wind up in the correct regions of lymph nodes?
(slide 24)
Chemokines
they make the B-cell go to the B-cell zone on the outside
and T-cell zone on the inside
Spleen
T-cell zone–> PALS (periarteriol lymphoic sheath)
B-cell zone = follicle
Why spleen important?
The spleen also removes aging and damaged blood cells and particles (such as immune complexes and opsonized microbes) from the circulation.
MACROPHAGES
Red Pulp in spleen (slide 26)
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
