De samenvatting is zeer compleet en uitgebreid op basis van alle gegeven theorie lessen en het boek. Ik heb met het leren van deze samenvatting een 9.0 gehaald op het tentamen. Wanneer deze samenvatting goed geleerd wordt, is het tentamen goed te halen.
Immunology → the scientific discipline that studies the immune system, which serves to
protect your body from infectious agents (viruses, parasites, bacteria, etc.) and cancer
Infectious disease
→ disorders caused by organisms such as bacteria, viruses, fungi or parasites
- Extracellular bacteria → live outside of host cells
- Diphtheria → most common cause of pediatric death before vaccines
- 10% of patients die after vaccination, 50% without vaccination
- Intracellular bacteria → live inside host cells
- These cannot be seen by the immune system
- Viruses → located inside of host cells
- Polio → highly contagious (besmettelijk) virus which causes paralysis and
deformation (vervorming)
- Measles → highly contagious virus which causes very severe complications
and often results in death
- Fungi
- Parasites
→ specific germs cause specific diseases = Koch’s postulate →
tests which germ causes the disease
1. The germ is found in diseased but not in healthy organisms
2. The germ needs to be isolated from the diseased organism
a. There are more than 1 germs present in the
diseased organism, but only 1 initiates the diseases
(so later the other germs join)
3. The disease causing germ is transferred to another
organism (and causes sickness)
4. The germ can be isolated again and be transferred to
another organism
5. Nowadays, you should be able to kill the germ and cure the
disease
Vaccinations
→ changes the incidence of diseases (prevents diseases)
- Vaccines lead to the eradication (uitroeiing) of the viral disease smallpox and reduces
the incidence of many infectious diseases
- Loss of confidence in vaccines → infectious diseases are reappearing
- Example: measles
- Measles in 2017 was low and started getting higher in 2018 → lower
incidence in 2020 and 2021 due to isolation (because of COVID)
- Now isolation is over → measles is back on the rise
- Samoa (island, separated population)
1
, - Viruses do not easily transfer but visiting people will bring viruses
(measles) with them
- Outbreak of measles results in a death rate of 1.5% due to
absence of vaccination
- Example: COVID-19 (end of 2019)
- 2020 (no vaccine) → 62.5 million cases, 1.5 million deaths
- 2021 (8 billion vaccines) → 265 million cases, 5.2 million deaths
- 2022 (13 billion vaccines) → 645 million cases, 6.6 million deaths
→ the spread of the disease is prevented by vaccines but… comparative
advantages of the virus will lower the effectiveness of the vaccine (so…
vaccines need to be optimized over time)
Do we really need these vaccins?
→ yes!
- Viral infections (like COVID-19) can have other effects besides causing death → e.g.
long COVID
- Long COVID is reported in all age groups
- In all age groups → more unvaccinated patients are hospitalized per
100.000 people
- Meningococcal disease → caused by a bacteria that inhibits the mouth and throat
- When entering the circulation, it causes sepsis and meningitis with a death
rate of 10% and severe complication
- In 2002 → vaccination program against type C and the incidence went
down
- In 2017 → type W was coming up but went down after starting the
vaccination program (for type W)
- Vaccination program did not work for people >80 years
- These people do not have the capacity to initiate new
immune responses
- They can only respond to diseases they have
seen before
More vaccines are needed nowadays
- Respiratory syncytial virus (RSV) pandemic → causes a common cold
- In preterm infants (vroeggeboren baby’s) RSV can cause severe
complications and asthma
- Vaccin can be made using the information we got during research on
COVID-19
COVID-19 vaccin
→ RNA virus
- The vaccine is directed to spike (S) proteins
- COVID-19 uses the S protein to enter host cells in the nose or airways
- Antibodies against this S protein prevents interaction of the S protein with the
host cells and so… prevents infection
- There are 2 types of COVID19 vaccines
1. Recombinant S protein
2. mRNA which encodes the S protein
2
,→ a successful SARS-CoV-2 vaccine involves the innate and adaptive immune system
forming memory B-cells (produce antibodies) and memory T-cells (cell-mediated virus
response)
Immunology
→ a potent immune response is important to combat (fight) infectious diseases
- Features of the immune response:
1. Specificity → the immune response is specific for an organism, protein of a
class of proteins
2. Diversity → you can mount (create) an immune response against everything
3. Memory → production of memory cells for a faster and stronger response to
infections you had before
a. This happens after vaccinations
4. Clonal expansion → proliferation of antigen specific cells (adaptive immune
system)
5. Specialization → mount different immune responses to different infections
6. Contraction and homeostasis → get rid of the immune response as soon as
the pathogen is cleared (to prevent further damage of the body)
7. Non-reactivity to self (autoimmunity)
Innate vs adaptive immune response
Innate Adaptive
- Specificity = group of microorganisms - Specificity = a single antigen
- First line of defense and fast response - Powerful but slow response
- Always active - Induced by a specific trigger
- Encodes in the germline DNA - Requires DNA rearrangements
- Memory response by epigenetic - Immunological memory (basis for
programming only vaccinations
→ there are also similarities between the innate and adaptive immune response:
- They have specificity (but through a different mechanism)
- Are not responsive to self antigens
→ DC cells connect the innate to the adaptive immune system
- Present information on the presence of pathogens or tissue damage to the adaptive
immune system
- Transport the associated antigens from the tissue to the lymph node
- The lymph node is where the adaptive immune cells are present
Cellular vs humoral immune system
Cellular (T-cells) Humoral
- Phagocytosis (granulocytes and - Production of antibodies
macrophages) - Antimicrobial peptides
- Antigen presentation (DC and - Complement system
macrophages)
- Lymphocytes (B-, T-, and NK-cells)
3
, The immune response
1. A microbe enters the epithelial barrier which
causes an immune response
2. Within 6-12 hours → innate immune cells* are
present in the infected tissue
a. They can kill the infectious pathogen
3. After days/weeks → adaptive immune system*
gets activated (build memory)
a. B-cells → produce antibodies against the
antigen
b. Effector T-cells → kill the infected cells
c. This adaptive immunity provides lifelong protection to this specific antigen
*The adaptive immune response
→ takes days/weeks
1. Once DC cells start to activate B- and T-cells in the lymph nodes the adaptive
immune response starts
2. Clonal expansion → B- and T-cells differentiate and proliferate
a. These try to eliminate the antigen (B-cells via
antibodies = humoral and T-cells via cell-mediated
immunity)
3. The amount of antigen goes down
4. The B- and T-cells go into apoptosis (= contraction and
homeostasis)
a. Memory cells remain for another infection of the
same antigen
*Cells of the immune system
- Lymphocytes → type of white blood cells (leukocytes)
- B-cells → humoral, antibody-driven adaptive immunity
- T-cells → cell-mediated cytotoxicity of the adaptive immune system
- NK cells → cell-mediated cytotoxicity of the innate immune system
- Granulocytes → contains particles with enzymes that are released during infections
- Neutrophils → phagocytosis and activation of bactericidal mechanisms
- Eosinophils → kills antibody-coated parasites
- Basophils → promotion of anti-parasitic immunity
- Macrophages → phagocytose microbes and dead cells, present antigens and
produce cytokines
- DC cells → process extracellular antigens through pinocytosis and present to T-cells,
detects tissue damage and presence of pathogens
- Mast cells → recognize parasites through IgE bound on their cell surface
The immune system and lymphatic transport
- Fluid that comes from the peripheral tissue will collect in a lymph vessel, goes
through the lymph nodes to the thoracic duct back into the blood
- This is a one-way street
- Initiation of the adaptive immune response takes place in the lymph nodes (DC cells)
4
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