IMMUNOLOGY
Lecture 1
The immune system includes leukocytes (immune cells), complement, antibodies
and lymphatics.
INNATE IMMUNE SYSTEM
Existing in one from birth.
Monocyte
Macrophages
Granulocytes (made from common myeloid cell precursor):
- Basophil
- Neutrophil
- Eosinophil
Lymphocytes (made from lymphoid cell precursor):
- NK-cells
First line of defense: the skin or epithelial tissue barrier.
Second line of defense: complement and innate immune cells.
Equal in all of us.
Pathogen recognition receptors (whether it is self or non-self):
- Differentiate between pathogen species (PAMP, DAMP).
,- Equal expression per cell subset.
,ADAPTIVE IMMUNE SYSTEM
All made from common lymphoid cell precursor.
Third line of defense: T and B cells, antibodies.
Different in all of us.
T cell receptor and B cell receptor:
- Differentiate within pathogen species (antigen, epitopes).
- Highly specific with different specificity per cell.
Hematopoiesis = the development of immune cells with two important precursors
(lymphatics and myeloid).
LYMPHATIC SYSTEM
Primary = for development of the adaptive immune system. This includes bone
marrow (B cells) and the thymus (T cells).
Secondary = for activation of the adaptive immune cells. This includes lymph
nodes, spleen and the gut associated lymphoid tissue (GALT).
Macrophages recruit neutrophils from bone marrow. They then collaborate and
clear the bacterial infection by phagocytosis.
Phagocytosis = the cell ‘eats’ the bacteria.
Dendritic cells initiate the adaptive immune system and secondary lymphoid
organs are activated.
A surface allows bacteria to enter the skin. Effector cells recognizes bacteria
and secretes cytokines, which causes vasodilation. Vasodilation causes an
increase of permeability of capillary wall. Chemokine directs fluids, proteins, and
cells from blood to tissue.
Cytokines = signaling molecule for activation.
Chemokine = signaling molecule for migration (google maps).
Pathogen = intact antigen.
Antigen = molecule or fragment (epitope) of pathogen recognized by T and B
cells of the immune system.
Epitope = the minimal portion of an antigen bound by antibodies on the BCR and
recognized by the TCR. This is a processed antigen.
T and B cells express multiple TCR or BCR, but all with one specificity per cell.
Only the ones with a receptor for ongoing infection will be activated in
, secondary lymphoid organs. These will proliferate and become a clone of cells, all
with the same receptor specific for one epitope. (This takes a week).
Cellular response = TCR binds to processed antigen (epitope) and activates other
cells which support the immune response.
Humoral response = BCR binds to epitopes on intact antigens and differentiate
into plasma cells, which can produce antibodies.
Antibody = broad range specific for the same pathogen, recognizing different
epitopes between antibodies, recognizing one epitope per antibody.
Functions of antibodies:
- Neutralization (couteract)
- Opsonization (tagging)
- Complement activation
- Activation of innate cells via antibody receptor interaction such as
enhanced phagocytosis and activation of granulocytes and NK cells.
COMPLEMENT SYSTEM
Complement system = complements ongoing inflammation and consists of plasma
proteins with enzymatic activity.
C3 is inactive, but it can be cleaved by C3 convertase into active components C3a
and C3b.
C3a = anaphylatoxin, immune cell recruitment.
C3b = opsonization and complement fixation, pathogen binding for phagocytosis
and lysis. Can also form the membrane attack complex (MAC) and pathogen lysis.
C5a = inflammation.
C5b = initiates MAC after being activated by C3b.
Anaphylatoxins (C3a) enhance inflammation within minutes through activation of
endothelium and immune cell recruitment. C3a and C5a increase blood-vessel
permeability, which allows complements and other plasma proteins to enter
infected tissue and allows leukocytes to enter infected tissue. Leukocytes also
activate resident macrophages.
Lecture 1
The immune system includes leukocytes (immune cells), complement, antibodies
and lymphatics.
INNATE IMMUNE SYSTEM
Existing in one from birth.
Monocyte
Macrophages
Granulocytes (made from common myeloid cell precursor):
- Basophil
- Neutrophil
- Eosinophil
Lymphocytes (made from lymphoid cell precursor):
- NK-cells
First line of defense: the skin or epithelial tissue barrier.
Second line of defense: complement and innate immune cells.
Equal in all of us.
Pathogen recognition receptors (whether it is self or non-self):
- Differentiate between pathogen species (PAMP, DAMP).
,- Equal expression per cell subset.
,ADAPTIVE IMMUNE SYSTEM
All made from common lymphoid cell precursor.
Third line of defense: T and B cells, antibodies.
Different in all of us.
T cell receptor and B cell receptor:
- Differentiate within pathogen species (antigen, epitopes).
- Highly specific with different specificity per cell.
Hematopoiesis = the development of immune cells with two important precursors
(lymphatics and myeloid).
LYMPHATIC SYSTEM
Primary = for development of the adaptive immune system. This includes bone
marrow (B cells) and the thymus (T cells).
Secondary = for activation of the adaptive immune cells. This includes lymph
nodes, spleen and the gut associated lymphoid tissue (GALT).
Macrophages recruit neutrophils from bone marrow. They then collaborate and
clear the bacterial infection by phagocytosis.
Phagocytosis = the cell ‘eats’ the bacteria.
Dendritic cells initiate the adaptive immune system and secondary lymphoid
organs are activated.
A surface allows bacteria to enter the skin. Effector cells recognizes bacteria
and secretes cytokines, which causes vasodilation. Vasodilation causes an
increase of permeability of capillary wall. Chemokine directs fluids, proteins, and
cells from blood to tissue.
Cytokines = signaling molecule for activation.
Chemokine = signaling molecule for migration (google maps).
Pathogen = intact antigen.
Antigen = molecule or fragment (epitope) of pathogen recognized by T and B
cells of the immune system.
Epitope = the minimal portion of an antigen bound by antibodies on the BCR and
recognized by the TCR. This is a processed antigen.
T and B cells express multiple TCR or BCR, but all with one specificity per cell.
Only the ones with a receptor for ongoing infection will be activated in
, secondary lymphoid organs. These will proliferate and become a clone of cells, all
with the same receptor specific for one epitope. (This takes a week).
Cellular response = TCR binds to processed antigen (epitope) and activates other
cells which support the immune response.
Humoral response = BCR binds to epitopes on intact antigens and differentiate
into plasma cells, which can produce antibodies.
Antibody = broad range specific for the same pathogen, recognizing different
epitopes between antibodies, recognizing one epitope per antibody.
Functions of antibodies:
- Neutralization (couteract)
- Opsonization (tagging)
- Complement activation
- Activation of innate cells via antibody receptor interaction such as
enhanced phagocytosis and activation of granulocytes and NK cells.
COMPLEMENT SYSTEM
Complement system = complements ongoing inflammation and consists of plasma
proteins with enzymatic activity.
C3 is inactive, but it can be cleaved by C3 convertase into active components C3a
and C3b.
C3a = anaphylatoxin, immune cell recruitment.
C3b = opsonization and complement fixation, pathogen binding for phagocytosis
and lysis. Can also form the membrane attack complex (MAC) and pathogen lysis.
C5a = inflammation.
C5b = initiates MAC after being activated by C3b.
Anaphylatoxins (C3a) enhance inflammation within minutes through activation of
endothelium and immune cell recruitment. C3a and C5a increase blood-vessel
permeability, which allows complements and other plasma proteins to enter
infected tissue and allows leukocytes to enter infected tissue. Leukocytes also
activate resident macrophages.
