Immunosero Lec M3 Flashcards
3 Main functions of Cellular Migration
- Deliver of leukocytes of myeloid lineage (mainly neutrophils and monocytes) from the circulation into tissue sites of infection or injury
- Delivery of lymphocytes from their sites of maturation
(bone marrow or thymus) to peripheral (secondary) lymphoid organs
-Delivery of effector lymphocytes from the secondary lymphoid organs in which they were produced to sites
of infection in any tissue, where they perform their protective functions
Deliver of leukocytes of myeloid lineage (mainly neutrophils and monocytes) from the circulation into
tissue sites of infection or injury
1st Main Function
Where are neutrophils and monocytes be typically found?
Peripheral Blood (Blood vessels)
Note
Neutrophil and monocytes would just continuously circulate along with blood From the circulation, whenever there would
be an infection or injury, they would travel from the circulation to specific tissue sites of infection or injury
Delivery of lymphocytes from their sites of maturation
(bone marrow or thymus) to peripheral (secondary) lymphoid organs
2nd Main Function
Lymphocytes that have not yet reached or matured in the bone marrow or thymus
Immature Lymphocytes
Note
Small lymphocytes could either stay in the bone marrow where they would become mature B cells
Lymphocytes that have matured either in the bone marrow or the thymus
Mature Lymphocytes
Note
basically a mature B cell or T cell
T cell or B cell that have not been exposed to antigens
Naive Lymphocytes
Note
Have not yet encountered bacteria,
fungi, or viruses.
No antigenic stimulation
main organ for
hematopoiesis
Bone Marrow
Bone marrow creates _________ that would become lymphocytes
Stem Cells
In the bone marrow, what are two things that would happen in dealing with lymphocytes
Certain percentage of small lymphocytes will either
- stay in the bone marrow
or
-they would travel to
the types
Note
If they stay in the bone marrow, the small lymphocytes would become B cells
If they travel in the thymus, they would
become T cells.
From the circulation, the Mature T cells and Mature B cells would now go to the secondary lymphoid organs, specifically
_______ and _______
lymph nodes and spleen
While the mature b cells and t cells are travelling to the secondary lymphoid organs, they
would now be considered ______ T cells and B cells.
Naive
Note
They have basically not yet been exposed to antigenic components
When they go the secondary lymphoid
organs (lymph nodes and spleen), they
would encounter antigens which will make them now become an ________ T cell and B cell
Activated
Note
From the activated form, they would be
required to go to different sites of infection to perform their protective function
T cell would either develop into ______ and ______
- T helper cell
- T Cytotoxic cell
B cell will become ______ or ______
- Plasma Cell
- Memory Cell
Delivery of effector lymphocytes from the secondary lymphoid organs in which they were produced to sites
of infection in any tissue, where they perform their protective functions
3rd Main Function
Note
Effector is somewhat synonymous to
activated
Sentinel cell refers to _____
Macrophage
Macrophage of the liver
Kupffer Cells
Whenever the sentinel cells encounter an
antigen, it would now release certain chemicals known as _______
Cytokines
Whenever the sentinel cells encounter an
antigen, it would now release certain chemicals known as _______
Cytokines
capable of creating molecules known as
chemokines
Microbes and Necrotic Tissue
Adhesion of circulating leukocytes to vascular
endothelial cells is mediated by 2 classes of molecules which are
- SELECTINS
- INTEGRINS
Note
Selectins and integrins have ligands or their
receptors
Are plasma membrane carbohydrate-binding adhesion molecules that mediate an initial step of low-affinity adhesion of circulating leukocytes to endothelial cells lining post capillary venules
Selectins
Note
Selectins are typically found in the surface of
the endothelium and they would only provide a weak initial attachment or affinity
What are two types of selectins?
P-selectin (CD62P) and E-selectin (CD62E)
It is stored in cytoplasmic granules of endothelial cells, and is rapidly redistributed to the luminal surface in response to histamine from mast cells and thrombin generated during blood coagulation
P-Selectin (CD62P)
Note
named because it was first found in platelets
P (Platelets) - selectin
Inside the endothelial lining, there would be
cytoplasmic granules
Inside the cytoplasmic granules is where
P-selectin is
How does P-selectin redistribute itself?
Due to histamine from mast cells and thrombin generated during blood coagulation
is the one responsible for converting fibrinogen into a fibrin
Thrombin
Note
Thrombin is generated whenever you would
have an injury or wound
Fibrin would act as a
_____ to capture cell
decrease
Net
is synthesize and expressed on the
endothelial cell surface within 1 to 2 hours in
response to the cytokines interleukin-1 (IL-1) and tumor necrosis factor (TNF), which are produced by
tissue sentinel cells (DCs and macrophages) in
response to infection
E-Selectin (CD62E)
Note
Microbial products such as lipopolysaccharide (LPS) also stimulate E-selectin expression on endothelial cells
E-selectin is found in the endothelial cell
surface
In the endothelial lining, there would be
endothelial cells. Inside the endothelial cells
is where E-selectin is.
They are usually produced due to the
presence of IL-1 and tumor necrosis factor
(TNF)
E-Selectin
What causes the expression of your E-selectin or which cytokine causes the
expression of E-selectin?
IL-1 and tumor necrosis factor
Note
Whenever macrophage secreted cytokine such as IL-1 and tumor necrosis factor, it would cause the expression of E-selectin
A third selectin that is expressed on leukocytes and not on endothelial cells.
L-selectin on neutrophils promotes the adhesion of these cells to endothelial cells that are activated by IL-1, TNF, and other inflammatory cytokines.
L-Selectin (CD62L)
Note
This is not part of the main selectins
It is found in leukocytes and not on endothelial cells
In adaptive immunity, this selectin is required for naïve T and B lymphocytes to home into lymph nodes through specialized blood vessels called high endothelial
venules (HEVs)
L-Selectin (CD62L)
Entry way of naive T and B cell
High Endothelial Venules (HEVs)
Note
The one that serves as a guide is the L-selectin
Which selectin is found in leukocytes?
L-Selectin
are cell surface proteins that mediate
adhesion of cells to other cells or to extracellular matrix, through specific binding interactions with various ligands
Integrins
Note
Found in cell surface or WBC
what stimulate leukocyte movement and regulate the migration of leukocytes from the blood to tissues
Chemokines
Note
are a large family of structurally homologous cytokines that stimulate leukocyte movement and regulate the migration of leukocytes
from the blood to tissues.
Chemokines would call WBC to the site of injury.
Cytokines would also call WBC but cytokines
mainly used to activate the different adhesion molecules
The name chemokine is a contraction of
Chemotactic Cytokine
Chemokines are subdivided into 4 groups. What are the 4 groups?
1st group - CC chemokines
2nd group - CXC chemokines
3rd group - C chemokines
4th group - CX3C chemokines
Chemokine plays two roles of inflammation, what are these?
- Increased adhesion of leukocytes to endothelium.
- Migration of leukocytes through blood vessels and toward the site of infection or tissue damage
Note
In inflammatory reactions, chemokines serve to recruit circulating leukocytes from blood vessels into
extravascular sites
Involved in the development of lymphoid organs, and
they regulate the traffic of lymphocytes and other leukocytes through different regions of secondary
lymphoid organs.
Chemokines
Note
Chemokines are required for the migration of DCs from sites of infection into draining lymph nodes
Leukocyte recruitment from the blood into tissues requires adhesion of the leukocytes to the endothelial lining of postcapillary venules and then movement
through the endothelium and vessel wall into the
extravascular tissue.
Leukocyte-Endothelial Interaction
There are four things that would occur
whenever there would be a WBC endothelial
interaction.
- Rolling
- Integrin activation by chemokines
- Stable adhesion
- Migration through endothelial
Note
Process of Leukocyte-Endothelial interaction’
- Selectin-mediated rolling of leukocytes on
endothelium - Chemokine-mediated increase in affinity of integrins
- Stable integrin-mediated arrest of leukocytes on endothelium
- Transmigration of leukocytes through the
endothelium
Leukocyte-endothelial interaction would begin when ever macrophages would be stimulated by microbes such as
- Antigen
- Bacteria
- Fungi
Known as the characteristics of the WBC which they are capable of squeezing through the tissues
Diapedesis
serves as a homing signal to find where the organisms is
Chemokines
What is the first leukocyte to migrate to sites of infection or tissue injury?
Neutrophils
Note
Monocyte would follow a few hours after
