Module 7 - Immunology

Question 1

What is the role of adjuvant in vaccination, and what are the two signals required for T cell activation?

Answer 1

Adjuvants in vaccines enhance the immune response by providing the necessary signals for T cell activation. The two signals required for T cell activation are:

Signal 1: Antigen Recognition - T cells recognize specific antigens presented by antigen-presenting cells (APCs) through the T cell receptor (TCR) interacting with peptide antigens on major histocompatibility complex (MHC) molecules.

Signal 2: Co-stimulation - Co-stimulatory signals, mediated by molecules on APCs (e.g., B7) and T cells (e.g., CD28), are essential for T cell activation and clonal expansion. Adjuvants enhance co-stimulation, leading to a more robust immune response.

Question 2

Name two types of vaccines apart from ‘subunit’ vaccines and describe how they deliver antigens to the immune system. Are all vaccine types equally reliant on added adjuvants, and if not, why?

Answer 2

Apart from ‘subunit’ vaccines, two other types of vaccines are:

Live Attenuated Vaccines: These vaccines contain weakened, live pathogens that replicate in the body. They deliver antigens by allowing the weakened pathogen to replicate, often not requiring added adjuvants due to their inherent immunogenicity.

Inactivated or Killed Vaccines: These vaccines contain pathogens that have been killed or inactivated. They deliver antigens without replication and may require added adjuvants to enhance immune response, as they may not provide as strong a stimulus as live attenuated vaccines.

Not all vaccine types are equally reliant on added adjuvants. Live attenuated vaccines often do not require adjuvants because the live pathogen itself is immunogenic, while inactivated or subunit vaccines may need adjuvants to boost their effectiveness. The necessity for adjuvants depends on the specific vaccine and its ability to stimulate the immune system.

Question 3

How can you calculate the percentage of people needed to be vaccinated to achieve herd immunity using the equation qc = 1 - 1/R0, if each infected person, on average, passes the infection to 10 other people?

Answer 3

To calculate the percentage of people needed for herd immunity using the equation qc = 1 - 1/R0, when each infected person infects an average of 10 others, you can use the formula:

qc = 1 - 1/R0

qc = 1 - 1/10

qc = 1 - 0.1

qc = 0.9

So, in this scenario, approximately 90% of the population would need to be vaccinated to achieve herd immunity.

Question 4

Describe how you would clean up a small biological spill (e.g. urine sample) on a tiled floor.

Answer 4

Immunological principles can be applied to biological spill cleanup as follows:
Safety Precautions: Utilize immunological knowledge about pathogen transmission to emphasize the importance of wearing appropriate personal protective equipment (PPE) to prevent contact with potentially infectious agents.
Contain the Spill: Recognize that containing the spill limits the potential exposure of individuals to pathogens, mirroring the immune system’s role in isolating and controlling infections.
Dispose of Waste: Understand the need to properly segregate and dispose of contaminated materials to prevent the spread of pathogens, analogous to immune responses isolating and eliminating pathogens.
Disinfect: Apply disinfectants that target a broad spectrum of microorganisms, similar to how the immune system employs antibodies and complement proteins to neutralize pathogens.
Decontaminate: Reapply disinfectants to ensure thorough pathogen inactivation, aligning with immune responses that eliminate residual pathogens.
Hand Hygiene: Emphasize the significance of handwashing to prevent potential pathogen transfer, reflecting the role of immunological defenses in warding off infections.
Reporting: Highlight the importance of promptly reporting spills and adhering to institutional protocols, akin to how immune responses trigger an alert when encountering pathogens.

Question 5

What are the key components of defence against infection, starting from the initial barriers?

Answer 5

The physical barriers and defence mechanisms that help prevent infections are called the innate immune system or the first line of defence. They include physical barriers such as the skin and mucous membranes, and mechanical defences such as tears, mucus, cilia, stomach acid, urine flow, and ‘friendly’ bacteria. They also include the increase of certain white blood cells that engulf and destroy invading microorganisms, and the inflammation process that limits the spread of infection.

Question 6

What distinguishes the innate immune response from the acquired immune response?

Answer 6

The innate response is rapid and does not have memory of previous infections, while the acquired immune response has specificity and memory.

Question 7

Can you name some innate immune cells and describe their functions?

Answer 7

Innate cells include neutrophils, macrophages, dendritic cells (DC), NK cells, and more. Phagocytosis is an important function of these cells.

Question 8

What initiates inflammation in the immune response, and what are the signs of inflammation?

Answer 8

Inflammation is initiated by tissue damage and/or specific pathogen molecules (PAMPs). The signs of inflammation include redness, heat, swelling, and pain.

Question 9

How do innate immune cells respond to pathogen molecules?

Answer 9

Innate immune cells have receptors for PAMPs, which lead to the release of chemokines, cytokines, and inflammation.

Question 10

What is the role of dendritic cells (DC) in the immune response

Answer 10

DC are important innate immune cells for activating T cells in the acquired immune response.

Question 11

Where do immune cells develop from, and where do T cells mature?

Answer 11

Immune cells develop from stem cells in the bone marrow, and T cells mature in the thymus.

Question 12

How does the lymphatic system facilitate the meeting of acquired immune cells with antigens?

Answer 12

The lymphatic system helps acquired immune cells meet up with antigens in lymph nodes.

Question 13

What are some components of acquired immunity, and what distinguishes it from innate immunity?

Answer 13

Acquired immunity involves T and B cells and has specificity and memory. It includes B cell antibody production, T helper cells, and cytotoxic T lymphocytes (CTL).

Question 14

How do B and T cells recognize antigens, and what is the result of this recognition?

Answer 14

B cells recognize part of an intact antigen, and T cells recognize a peptide antigen on MHC. This recognition leads to clonal selection.

Question 15

What is the role of adjuvants in vaccines, and how do they work?

Answer 15

Adjuvants provide the role of the PAMP in vaccines by enhancing the immune response. They stimulate the innate immune system to improve the vaccine’s effectiveness.

Question 16

What are some approaches to generating antigens for vaccination?

Answer 16

There are various approaches, including using live attenuated pathogens, purified antigens, or mRNA encoding the antigens.

Question 17

Explain the concepts of herd immunity and the reproductive number (R0 and Reff) in vaccination.

Answer 17

Herd immunity is the indirect protection of a population through a sufficiently high percentage of individuals being immune. R0 is the basic reproductive number, while Reff is the effective reproductive number, which considers immunity in the population.

Question 18

Why is it important to counter misinformation in maintaining community levels of vaccination?

Answer 18

Misinformation can lead to vaccine hesitancy and reduced vaccination rates, which can compromise herd immunity and increase the risk of disease outbreaks.

Question 19

Could you list some topics related to infectious diseases mentioned in the key points?

Answer 19

Some topics related to infectious diseases mentioned include immunodeficiency, genetic deficiencies, AIDS, autoimmunity, chronic inflammatory diseases, allergies, microbiome, and western lifestyle diseases.

Question 20

Can you provide some insights into the immune response in the context of COVID-19?

Answer 20

COVID-19 is an infectious disease, and the immune response plays a crucial role in how the body defends against the SARS-CoV-2 virus. Understanding this response is important for vaccine development and treatment strategies.

Question 21

Innate immune defences are

Answer 21

mediated by soluble factors like complement proteins and antibody as well as a range of phagocytic cells

Question 22

What are some characteristics and classification criteria for viruses?

Answer 22

Viruses are living organisms consisting of DNA, RNA, and protein AND viruses are classified based on their genetic makeup (nucleic acid and arrangement of nucleic acid), structure, and symmetry

Question 23

True of False: allergic rhinitis is NOT an autoimmune disease?

Answer 23

TRUE

Question 24

Which is the appropriate personal protective equipment (PPE) when dealing with infected patients that can transmit an airborne respiratory infection?

Answer 24

Gloves, gown, respirator, hazmat suit and practice good hand hygiene and respiratory/cough etiquette

Question 25

Which are the potential sources of infection in the health-care setting?

Answer 25

Taps, door handles, light switches, medical supplies, blood pressure machine, sterile gowns

Question 26

The first cells recruited from the blood to a site of tissue infection are

Answer 26

neutrophils

Question 27

A patient becomes infected with Staphylococcus aureus bacteria in a wound to the skin of the hand. Naïve T cells would initially be activated by bacterial antigens at which site?

Answer 27

the draining lymph node

Question 28

How do antibodies act

Answer 28

Neutralisation - antibody binding to virus can block entry into cells. Antibody can
also neutralise bacterial toxins (e.g. tetanus toxin) and prevent effects on cells
2. Opsonisation (coating of organisms) to promote phagocytosis via receptors for
antibodies on phagocytes.
3. Activation of the complement system (see previous lecture) – leading to bacterial
lysis and inflammation
4. IgE binds to mast cells. When it recognises antigen (frequently allergens) the mast
cells release histamine (inflammatory small molecule).

Question 29

For an infectious organism, the basic reproduction number, R0 is -

Answer 29

the average number of people in a susceptible population that will be infected by one person, and depends on population density

Question 30

What do most antibody production depend on?

Answer 30

Most antibody production depends on T cell activation

Question 31

What is the main antigen presenting cell (APC) involved in activation of naive T cell

Answer 31

Dendritic cell

Question 32

What are the different approaches to vaccination

Answer 32

Live attenuated organisms: The pathogen has become non-virulent through mutations. Examples of attenuated viral vaccines - yellow fever; measles/mumps/rubella; chicken pox.

Live vectored vaccines: e.g. Adenovirus engineered to express SARS-CoV2 spike protein - AstraZeneca vaccine

Inactivated (killed) pathogens: Pathogen killed by chemical treatment, detergent or heat. Examples for viruses - influenza, inactivated polio vaccine; bacteria- Vibrio cholerae (cholera), Yersinia pestis (plague). Effect can often be improved with adjuvants.

Subunit vaccines: Purified single antigen or group of antigens used as vaccine. Good safety profile.
Examples – hepatitis B, Bordetella pertussis – whooping cough, human papilloma virus. Needs adjuvant.

Toxoid vaccines: Vaccinate with a toxin secreted by the pathogen. Example – tetanus, diptheria

mRNA vaccines: Administer mRNA that needs to get into host cells to be translated into the pathogen
protein. Pfizer and Moderna SARS-CoV2 vaccines. RNA itself can act as an adjuvant.

Question 33

Which antibody is involved in the allergy response

Answer 33

IgE

Prior sensitization to allergen by activation of acquired immune responses, resulting in production of IgE antibody specific for the allergen. The IgE binds to receptors on mast cells

Question 34

What are the major retroperitoneal organs

Answer 34

Kidneys
Adrenal glands (suprarenal glands)
Aorta
Inferior vena cava
Pancreas (only the posterior part, except for the tail)
Duodenum (the first part, known as the “duodenal cap”)
Ascending and descending colon (the portions of the large intestine)
Rectum (lower part)

Question 35

Which site does the activation of naive T cells by recognition of foreign antigens occur

Answer 35

spleen and lymph nodes.
These secondary lymphoid organs are where antigen-presenting cells (such as dendritic cells) interact with naive T cells to initiate immune responses upon encountering foreign antigens.

Question 36

What are antibodies

Answer 36

Antibodies are proteins released by B cells that are capable of binding a huge variety of different molecular structures including pathogens like bacteria and viruses, as well as other foreign substances.

Question 37

What are Cytotoxic T lymphocytes

Answer 37

Cytotoxic T lymphocytes (CTLs), also known as CD8+ T cells, play a crucial role in identifying and killing virus-infected cells and cancer cells. They are part of the adaptive immune response and are specific for foreign antigens but can also recognize abnormal or infected host cells.

Question 38

What are autoimmune diseases triggered by

Answer 38

Autoimmune diseases can be triggered or exacerbated by various environmental factors, including infections, which can lead to an inappropriate immune response against the body’s own tissues. Autoimmune diseases are not typically characterized by phagocytosis of cells by macrophages and are not necessarily more common in the tropics or in men. The prevalence of autoimmune diseases can vary widely, and trends may not be uniform worldwide.