13-10-21 - Introduction to Immunology Flashcards
Where can different pathogens be found around the cell?
What is an example of each?
- Pathogens can be found exclusively in the cell e.g influenza
- Pathogens can be found inside. outside of the cell, and even on things like RBCs e.g malaria
- Pathogens can be found on the surface of the cell, and in macrophages where they hide form the immune system e.g TB
- Pathogens can be found in gaps on the cell membrane surface e.g Streptococcus
What are the 2 types of immune system?
How fast do they each respond?
How are each improved?
What does the 2nd have that the 1st does not?
Innate immune system -
- First line of defence
- Ready, prepared, and can respond rapidly
- Not improved by further exposure
Adaptive immune system -
- Second line of defence
- Requires a period of time to generate activity and respond
- Improved by further exposure.
- The adaptive immune system has specificity and memory for pathogens it has previously seen, leading to faster and stronger responses against a reoccurring pathogen
What are 3 physical protections of the immune system?
What are 2 biochemical protections of the immune system?
- Physical
- Barriers e.g epithelia and skin
- Movement e.g cilia
- Trapping e.g mucus
- Biochemical (toxic to invading organisms)
- Low pH e.g sweat, stomach acid, vaginal secretions
- Lysozyme (hydrolytic enzyme) secretion
What does the body do if the barriers are breached?
What are the cells involved
- When the barriers of the body are breached, the body will attempt to contain and localise the pathogen using phagocytotic cells that can undergo phagocytosis
- Cells involved are neutrophils and monocytes (blood)/macrophages (tissue)
What are 4 chemicals that help in early stages of infection?
- Acute phase proteins
- Complement proteins
- Interferons
- Cytokines
What is CRP?
What is its role in response against infection?
What process does it aid in?
What is CRP good indication of?
What are its normal levels?
What can it rise to?
- CRP (C-reactive protein) is the most important acute phase protein
- It is able to be released in large quantities and rise in the blood stream rapidly during the onset of infection
- CRP helps in the process of opsonisation by binding the lipids on bacterial cells or dead infected cells.
- CRP is a good indication of the inflammatory process/infection in patients
- CRP has a normal range of 5-10µg/ml and can rise to several hundred µg/ml, with anything above 10-20µg/ml being significant (vast dynamic range)
What are the 3 complement pathway functions?
Lysis -
- Bacteria can be killed directly by activating the complement pathway
- Some components of the complement pathway can bind to bacteria and punch holes in them, causing lysis of the bacteria (disintegration of the cell)
Chemotaxis -
- Chemotaxis is the movement of a particular cell/organism in a direction that corresponds to a gradient increase or decrease in the concentration of a particular substance
- The complement pathway can cause chemotaxis in phagocytes and draw them towards the site of infection.
Opsonization -
- The complement pathway generates fragments of complementary components called opsonin’s
- Opsonin’s are substances that coat cells/bacteria (example of an opsonin is a C3b fragment)
- Opsonin’s are complementary in shape to receptors on the phagocytic cells, which enhances the ability of the phagocyte to phagocytose the cell/bacteria
- The process of coating a cell/bacterium with opsonin’s is opsonization
What are the 3 different types of interferons (IFN)?
What is each type produced by?
What are the functions of each type?
What can lymphocytes then do in response to interferons?
- IFNα released by leukocytes (WBC)
- IFNβ released by fibroblasts
- IFNγ (gamma) released by T lymphocytes
- If an endothelial cell or fibroblast cell are infected by a virus, those cells will start to secrete IFNα and IFNβ
- They act as warning signals to nearby cells to alter their function (turn off expression for certain genes or move in a different direction) in order to be worse hosts for the viruses to enter and replicate in (anti-viral resistance
- IFNγ is released with an immune response and is a very strong activator of immune responses
- T cells and Natural killers (lymphocytes) have the ability to detect when a viral infection is present, and kill those specific cells.
What do antigens stimulate?
What makes an effective antibody immune response to antigens?
- Antigens are agents that stimulate an immune response
- In an effective immune response, we want antibodies that have a high degree of affinity for the antigen and can bind to them (fix complement)
- We also want an antibody that is capable of binding to monocytes
What are the 2 different parts of antibodies?
What are they used for?
What does this allow antibodies to be used for?
- The antibody consists of 2 identical Fab fragments for binding antigens from different pathogens
- The antibody also contains an Fc fragment, which is used to bind to monocytes and activations of complement cascades.
- Antibodies are also able to bind to spike proteins of viruses outside of the cell, which prevents them from interacting with receptors on cells.
What can be done to further enhance the ability of phagocytes to phagocytose a pathogen in regards to opsonisation?
What are antibodies another example off?
• Antibody binding gives a further enhance, but antibodies binding and opsonization give the biggest enhance in the phagocytes ability to phagocytose the pathogen (multiple opsonins binding)
Antibodies are an example of another opsonise, as they are a substance that increase chance of phagocytosis
What is antibody response like when introduced to an antigen for the first time (primary response)?
What is the most common antibody in the blood?
What is the antibody response like when introduced to the same antigen again?
- On the first time of encountering an antigen, an immune response will occur that consists of IgM
- After some time, there will be an IgG response that will overtake the IgM response
- IgG is the most common antibody in the blood.
- As the antigen clears, the antibody levels decrease.
- This process is known as the primary response to a pathogen
- If the same antigen is encountered again, the IgM response will be similar, but the IgG response will be much faster and much higher
- This is known as the secondary response to the same pathogen
Why are bacteriophages used in immune response tests?
Why are the primary responses to antigens different in different people?
- Bacteriophages are viruses that infect bacteria.
- They will not cause damage to the host, but can be used to measure immune response
- We all have different levels of immune response to different antigens because we all have different genes.
- We are an outbred population
When administering vaccines, what are we actually trying to protect against?
What do we put in the vaccines?
What effect does this have on our own immune response?
What are the names of 3 well known viral diseases that we vaccinate against?
- In vaccines, we are not trying to protect against bacteria (e.g clostridium), but the toxins produced by the bacteria, which can cause damage to neuronal cells.
- We put an inactive variant of the toxin called toxoids in the vaccine and administer the vaccine so the body can make a primary response.
- This means when we encounter the actual toxin, we have a much stronger secondary response.
- Measles, mumps, and rubella are 3 well known viral diseases that are vaccinated against with the MMR vaccine.
What are the cells that produce large numbers of antibodies?
What can they also be known as?
What helps them do this?
- Plasma cells, also known as B-cells or B-lymphocytes, are responsible for producing large quantities of antibodies
- They have a large amount of cytoplasm, which aids them in producing large quantities of antibodies.
What causes auto-immune haemolytic anaemia?
How is this condition treated?
- Auto-immune haemolytic anaemia is caused when people produce antibodies from B – Cells that are capable of binding onto erythrocytes (RBCs) and causing lysis
- This activates the complement cascade, which results in the cells in the immediate proximity undergoing lysis
- This then causes anaemia, due to a lack of RBCs
- This condition is treated by removal of the antibodies, or a blood transfusion
What can combination of the father and mothers’ antigens in a foetus cause?
What protects against this?
How is antibody production stimulated in the mother during pregnancy?
What is the most common antibody present in new-born children?
Why is this the case?
- The fathers’ antigens in the foetus can potentially trigger an immune response from the mother’s immune system against the foetus, which can be dangerous
- Oestrogen inhibits T-cells which could reject the foetus
- In pregnancy, oestrogens stimulate IgG and IgA antibody production
- In new-born children, maternal IgG from the placenta is the most common antibody present in the foetus, which peaks at birth
- This is because the baby does not produce significant levels of antibodies for a few months, so the Mothers IgG is needed to protect the baby in the meantime.
What are 3 potential failures of the immune system?
Autoimmunity -
- When the immune system generates an immune response against the bodies own tissues/organs, this is known as autoimmunity
- It is a loss of tolerance to self, which results in the immune system reacting to self
Immunodeficiency -
- This is the full or partial impairment of the immune system.
- Primary immunodeficiencies are causes by genetic defects
- Secondary immunodeficiencies are caused by environmental factor, such as malnutrition, or HIV, which depletes certain subsets of T-Cells and makes the body far more susceptible to infection
Hypersensitivity reactions (allergic reactions) -
- Immune responses that are exaggerated or inappropriate against an antigen or allergen.
What is Rheumatoid arthritis?
What does it cause?
How can it be caused?
- RA is an autoimmune disease which results in significant damage of joints, cartilage, and nearby bone.
- This leads to significant damage, pain and loss of function in joints
- This disease can be antibody or cell mediated
What causes type 1 diabetes?
What can it be caused by?
- Type 1 diabetes is an autoimmune disorder where the immune system kills insulin producing cells in the pancreas
- This process can be antibody or cell medicated.
What is the thyroid responsible for?
What can antibodies do to these products?
What is an autoimmune condition associated with the thyroid?
How is it caused?
- The thyroid is responsible for producing a wide range of hormones in the body.
- Anti-bodies can bind to these hormones and reduce their activity in the body
- Hashimoto’s thyroiditis is causes by antibodies binding to the thyroid gland, causing it to inflame and become enlarged.
