Tijmen Lourens Summary Immunology
Immunology
Lecture 2: Cells and tissues of the immune system
Innate immune system:
- Not very specific
- Very fast → immediately ready
- No specific memory
Adaptive (acquired) immune system:
- Very specific
- Slow (needs time to respond properly)
- Specific memory
o 2nd encounter with same bacteria/virus/parasite → very fast and specific
response
The immune system is everywhere
- Blood: circulation/transport of immune system
- Tissues: surveillance and effector cells
- Lymphoid organs:
o Primary: bone marrow / thymus → generation of immune cells
o Secondary: responses of the lymphocytes → adaptive immune responses
Innate immune system doing 2 things:
- Killing and elimination of the micro-organisms
o By their cells and soluble proteins
- Control of the infection
o Give of signals that there is an infection to warn the adaptive immune system
But first: the cell of the innate immune system must be able to recognize that there are
bacteria and viruses that invaded the body. How?
- There is global recognition of microbes by the innate immune system:
o The pattern recognition receptors: IT IS GLOBAL. Only looks for molecules
and components that can only be made by bacteria and viruses such as
double stranded RNA or mannose → non-self.
Toll-like receptors:
- Important group of pattern recognition receptors
- Ten different human TLRs (TLR1-10)
- Evolutionary ‘old’ (before antigenreceptors)
- Can discriminate between ‘self’ and micro-organism
- Without TLRs: weak immune responses
- Used as adjuvants for vaccines!
o To promote the immune response because you need interaction with TLRs so
your body knows that it has been infected → to become immune
- Type 1 innate cells: natural killer cells: killing of virus-infected cells
,Tijmen Lourens Summary Immunology
- Granulocytes / monocytes / phagocytosis
macrophages (phagocytes)
- Eosinophilic granulocytes killing of worms
- Mast cells release of histamines
- Dendritic cells antigen presentation
Professional phagocytes:
- Most important effector task of the innate immune system!!
2 types:
- Neutrophilic granulocytes (neutrophils)
- Tissue macrophages (monocytes)
Why are there 2 types of phagocytes?
- That the contents of neutrophils is very aggressive
o Has content that is able to construct the tissue
▪ Infections can take place everywhere in a tissue (also bone) and there
must be a way that also in those locations these neutrophils can move
to that particular place. They need to construct the connective tissue
to reach those places.
▪ Neutrophils have enzymes that can degrade the collagen → can
cause a lot of harm / damage to your body.
• Therefore: in normal conditions the neutrophils are kept in the
blood and enter the tissues only if they are needed → when
infection is going on.
• The neutrophils only live a few days and can be generated very
quickly → only when needed
- Macrophages are far less dangerous and aggressive.
o Are found everywhere
o Long-lived
▪ Tattoo’s are based on tissue macrophages because they are long-lived
o Low bactericidal activity
o Classical (M1) macrophages: phagocytosis
Non-classical (M2) macrophages: Are involved in tissue repair
Fight against extracellular microbes!!
,Tijmen Lourens Summary Immunology
Important type 1 innate immune cell: Natural Killer Cell
- T-lymphocyte-like cells without antigen receptor
o Response against intracellular microbes and damaged/tumor cells
They are able to kill target cells:
And they can activate cells
- Interferon gamma (IFN-y) can be produced
by the natural killer cells
, Tijmen Lourens Summary Immunology
All cells have the MHC class I receptors, they are for antigen presentation. Many tumour
cells lack those MHC class I receptors, the natural killer cells induce apoptosis. Also virally
infected cells lack the MHC I receptors.
If a cell is stressed, you get an upregulation of many ligands. They can interact with the
activating interactions → there is not enough inhibition anymore → leading to apoptosis.
ADCC can recognize tumour antigens, some tumour cells do have the MHC I receptor so they
do have the inhibition. But the ADCC recognizes the activating tumour cell interactions
leading to apoptosis.
So: activation = apoptosis.
Elimination of micro-organisms by the
innate immune system:
Immunology
Lecture 2: Cells and tissues of the immune system
Innate immune system:
- Not very specific
- Very fast → immediately ready
- No specific memory
Adaptive (acquired) immune system:
- Very specific
- Slow (needs time to respond properly)
- Specific memory
o 2nd encounter with same bacteria/virus/parasite → very fast and specific
response
The immune system is everywhere
- Blood: circulation/transport of immune system
- Tissues: surveillance and effector cells
- Lymphoid organs:
o Primary: bone marrow / thymus → generation of immune cells
o Secondary: responses of the lymphocytes → adaptive immune responses
Innate immune system doing 2 things:
- Killing and elimination of the micro-organisms
o By their cells and soluble proteins
- Control of the infection
o Give of signals that there is an infection to warn the adaptive immune system
But first: the cell of the innate immune system must be able to recognize that there are
bacteria and viruses that invaded the body. How?
- There is global recognition of microbes by the innate immune system:
o The pattern recognition receptors: IT IS GLOBAL. Only looks for molecules
and components that can only be made by bacteria and viruses such as
double stranded RNA or mannose → non-self.
Toll-like receptors:
- Important group of pattern recognition receptors
- Ten different human TLRs (TLR1-10)
- Evolutionary ‘old’ (before antigenreceptors)
- Can discriminate between ‘self’ and micro-organism
- Without TLRs: weak immune responses
- Used as adjuvants for vaccines!
o To promote the immune response because you need interaction with TLRs so
your body knows that it has been infected → to become immune
- Type 1 innate cells: natural killer cells: killing of virus-infected cells
,Tijmen Lourens Summary Immunology
- Granulocytes / monocytes / phagocytosis
macrophages (phagocytes)
- Eosinophilic granulocytes killing of worms
- Mast cells release of histamines
- Dendritic cells antigen presentation
Professional phagocytes:
- Most important effector task of the innate immune system!!
2 types:
- Neutrophilic granulocytes (neutrophils)
- Tissue macrophages (monocytes)
Why are there 2 types of phagocytes?
- That the contents of neutrophils is very aggressive
o Has content that is able to construct the tissue
▪ Infections can take place everywhere in a tissue (also bone) and there
must be a way that also in those locations these neutrophils can move
to that particular place. They need to construct the connective tissue
to reach those places.
▪ Neutrophils have enzymes that can degrade the collagen → can
cause a lot of harm / damage to your body.
• Therefore: in normal conditions the neutrophils are kept in the
blood and enter the tissues only if they are needed → when
infection is going on.
• The neutrophils only live a few days and can be generated very
quickly → only when needed
- Macrophages are far less dangerous and aggressive.
o Are found everywhere
o Long-lived
▪ Tattoo’s are based on tissue macrophages because they are long-lived
o Low bactericidal activity
o Classical (M1) macrophages: phagocytosis
Non-classical (M2) macrophages: Are involved in tissue repair
Fight against extracellular microbes!!
,Tijmen Lourens Summary Immunology
Important type 1 innate immune cell: Natural Killer Cell
- T-lymphocyte-like cells without antigen receptor
o Response against intracellular microbes and damaged/tumor cells
They are able to kill target cells:
And they can activate cells
- Interferon gamma (IFN-y) can be produced
by the natural killer cells
, Tijmen Lourens Summary Immunology
All cells have the MHC class I receptors, they are for antigen presentation. Many tumour
cells lack those MHC class I receptors, the natural killer cells induce apoptosis. Also virally
infected cells lack the MHC I receptors.
If a cell is stressed, you get an upregulation of many ligands. They can interact with the
activating interactions → there is not enough inhibition anymore → leading to apoptosis.
ADCC can recognize tumour antigens, some tumour cells do have the MHC I receptor so they
do have the inhibition. But the ADCC recognizes the activating tumour cell interactions
leading to apoptosis.
So: activation = apoptosis.
Elimination of micro-organisms by the
innate immune system:
