Lecture 1 Immunology Introduction:
Infectious diseases are caused by extracellular or intracellular bacteria, fungi,
parasites, or viruses. To decrease the severity of the disease itself but also the spread
of diseases, vaccinations were invented in 1798.
Koch's postulate envelopes the process of identifying the germ that is responsible for
causing the disease. Firstly, you need to ensure that the germ is found in abundance in
a diseased organism, while it is not found in a healthy organism. Secondly, it must be
possible to isolate the germ from the diseased organism, and it should be possible to
grow the germ in a pure culture. Thirdly, when the germ is transferred from this culture
into a healthy organism it should cause (the same) disease. When the germ can also be
isolated from this newly infected organism, it can be said for certain that this certain
germ is the cause of the disease.
To combat infectious diseases, a potent immune response is needed. This is the
method of the human body to deal with these pathogens.
The immune response can consist of a variety of things. The features of the immune
response are:
• Innate vs adaptive immune system
o Specific vs non-specific immune responses
• Self vs non-self
• Immunological memory
• Immunity vs tolerance
• Cellular vs humoral immunity
White blood cells (Leukocytes) are the most important cells in the immune system.
They originate from hematopoietic stem cells. Mature leukocytes often circulate (or
more like patrol) in the body using blood and lymph systems. However, certain tissues
also contain a large number of specialized tissue-resident leukocytes. Other important
,cells for the immune response are cells such as epithelial and endothelial cells.
The immune response can very loosely be described multiple layers of defence.
The innate and adaptive (Acquired) immune systems differ very much.
• Innate immune system
o Specificity; groups of microorganisms
o Fast response, first defence
o Always active
o Encoded in the germline DNA
o Memory response by epigenetic programming only
o Not responsive to self
• Adaptive immune system
o Specificity; a single (protein) antigen
o Slow response but very powerful
o Induced by specific trigger
, o Requires DNA rearrangements
o Source of specific immunological memory and basis for vaccination
o A very large degree of diversity
o Specific memory response
o Not responsive to self
The different steps of an immune response start at different times and also last for
different periods of time.
• Humoral immune system
o Complement system
o Anti-microbial peptides
o Antibodies (immunoglobulins)
o B lymphocyte driven
o Directed to extracellular pathogens
o Vaccination can just be antibodies (Passive immunization)
• Cellular immune system
o Phagocytes
▪ Granulocytes
• Neutrophils
• Mast cells
▪ Monocytes
• Macrophages
• Dendritic cells
o Antigen presentation
▪ Dendritic cells
▪ Macrophages
o Cytotoxicity
▪ T lymphocytes
▪ Natural killer (NK) cells
o T lymphocyte driven
o Directed to intracellular and extracellular pathogens
o Vaccination requires weakened microbes (Active immunization)
The lymphatic system is used by the body to transport lymph. This lymph is transported
through lymph vessels, and these vessels can transport the lymph from tissue to the
lymph nodes, or the other way around. The transport of lymph and lymphocytes back
into the bloodstream happens at the vena cava.
The initiation of the adaptive immune response takes place in the lymph nodes.
The innate immune system is managed by a few different cells, namely;
, • Neutrophilic granulocytes
o The most common leukocyte
o Essential for the first response to infection
o Phagocytosis and killing of the pathogen
• Macrophages
o Phagocytosis of microbes but also dead cells
o Presenting antigens to effector or memory T cells
o Producing cytokines to induce inflammation
o Recruiting adaptive immune response
o Critical for tissue repair processes
• Dendritic cells
o Phagocytosis of microbes but also dead cells
o Present antigens to naive T cells
o Producing cytokines to induce inflammation
o Recruiting adaptive immune response
• Eosinophilic granulocytes
o Present in the mucosa of the lung, urogenital tract and the GI tract
o Can be recruited from the bloodstream during an inflammatory response
o Contribute to immunity against parasites/worms
• Basophilic granulocytes
o A rare subset of blood leukocytes
o The same functions as Eosinophilic granulocytes
• Mast cells
o Tissue resident cells of barrier tissues such as the skin and mucosal
tissue
o Release histamines
o Can recognize parasites
• Natural killer cells (NK)
o A type of innate lymphocytes
o Contributing to killing of transformed or virus-infected cells
Dendritic cells have a very important function in the immune system. It is the
connection between the innate and adaptive immune systems. By conveying
information on the presence of microbes and/or tissue damage to the adaptive immune
system, the adaptive immune system knows when to act. The conveying of the
information is done by transporting the associated antigens from the tissue to the
draining lymph node, where the adaptive immune cells can work with the antigens.
Infectious diseases are caused by extracellular or intracellular bacteria, fungi,
parasites, or viruses. To decrease the severity of the disease itself but also the spread
of diseases, vaccinations were invented in 1798.
Koch's postulate envelopes the process of identifying the germ that is responsible for
causing the disease. Firstly, you need to ensure that the germ is found in abundance in
a diseased organism, while it is not found in a healthy organism. Secondly, it must be
possible to isolate the germ from the diseased organism, and it should be possible to
grow the germ in a pure culture. Thirdly, when the germ is transferred from this culture
into a healthy organism it should cause (the same) disease. When the germ can also be
isolated from this newly infected organism, it can be said for certain that this certain
germ is the cause of the disease.
To combat infectious diseases, a potent immune response is needed. This is the
method of the human body to deal with these pathogens.
The immune response can consist of a variety of things. The features of the immune
response are:
• Innate vs adaptive immune system
o Specific vs non-specific immune responses
• Self vs non-self
• Immunological memory
• Immunity vs tolerance
• Cellular vs humoral immunity
White blood cells (Leukocytes) are the most important cells in the immune system.
They originate from hematopoietic stem cells. Mature leukocytes often circulate (or
more like patrol) in the body using blood and lymph systems. However, certain tissues
also contain a large number of specialized tissue-resident leukocytes. Other important
,cells for the immune response are cells such as epithelial and endothelial cells.
The immune response can very loosely be described multiple layers of defence.
The innate and adaptive (Acquired) immune systems differ very much.
• Innate immune system
o Specificity; groups of microorganisms
o Fast response, first defence
o Always active
o Encoded in the germline DNA
o Memory response by epigenetic programming only
o Not responsive to self
• Adaptive immune system
o Specificity; a single (protein) antigen
o Slow response but very powerful
o Induced by specific trigger
, o Requires DNA rearrangements
o Source of specific immunological memory and basis for vaccination
o A very large degree of diversity
o Specific memory response
o Not responsive to self
The different steps of an immune response start at different times and also last for
different periods of time.
• Humoral immune system
o Complement system
o Anti-microbial peptides
o Antibodies (immunoglobulins)
o B lymphocyte driven
o Directed to extracellular pathogens
o Vaccination can just be antibodies (Passive immunization)
• Cellular immune system
o Phagocytes
▪ Granulocytes
• Neutrophils
• Mast cells
▪ Monocytes
• Macrophages
• Dendritic cells
o Antigen presentation
▪ Dendritic cells
▪ Macrophages
o Cytotoxicity
▪ T lymphocytes
▪ Natural killer (NK) cells
o T lymphocyte driven
o Directed to intracellular and extracellular pathogens
o Vaccination requires weakened microbes (Active immunization)
The lymphatic system is used by the body to transport lymph. This lymph is transported
through lymph vessels, and these vessels can transport the lymph from tissue to the
lymph nodes, or the other way around. The transport of lymph and lymphocytes back
into the bloodstream happens at the vena cava.
The initiation of the adaptive immune response takes place in the lymph nodes.
The innate immune system is managed by a few different cells, namely;
, • Neutrophilic granulocytes
o The most common leukocyte
o Essential for the first response to infection
o Phagocytosis and killing of the pathogen
• Macrophages
o Phagocytosis of microbes but also dead cells
o Presenting antigens to effector or memory T cells
o Producing cytokines to induce inflammation
o Recruiting adaptive immune response
o Critical for tissue repair processes
• Dendritic cells
o Phagocytosis of microbes but also dead cells
o Present antigens to naive T cells
o Producing cytokines to induce inflammation
o Recruiting adaptive immune response
• Eosinophilic granulocytes
o Present in the mucosa of the lung, urogenital tract and the GI tract
o Can be recruited from the bloodstream during an inflammatory response
o Contribute to immunity against parasites/worms
• Basophilic granulocytes
o A rare subset of blood leukocytes
o The same functions as Eosinophilic granulocytes
• Mast cells
o Tissue resident cells of barrier tissues such as the skin and mucosal
tissue
o Release histamines
o Can recognize parasites
• Natural killer cells (NK)
o A type of innate lymphocytes
o Contributing to killing of transformed or virus-infected cells
Dendritic cells have a very important function in the immune system. It is the
connection between the innate and adaptive immune systems. By conveying
information on the presence of microbes and/or tissue damage to the adaptive immune
system, the adaptive immune system knows when to act. The conveying of the
information is done by transporting the associated antigens from the tissue to the
draining lymph node, where the adaptive immune cells can work with the antigens.
