Microorganisms, Infection, and Immunity 2 - MII2, University of Edinburgh

What is the big three

Malaria, HIV/AIDS/, Tuberculosis

What is intra-host adaptation

Immune system localises the the microorganism to one particular site in the body. Anywhere else triggers a response

What is inter-host adaptation

microorganisms that cause species barriers and can be leathal to different species

What is zoonosis?

humans to animals

What is innate immunity?

Nonspecific protection against foreign substances indiscriminantly.

All cells but lymphocytes.

What is adaptive immunity?

the body's ability to recognize and defend itself against distinct invaders and their products

What is CFR

case fatality rate

What are live attenuated vaccines?

They are weakened but still active organisms

What are dead/subunit vaccines?

vaccines using a part of a microorganism. Not as harsh as live attenuated vaccines

What are viral vectors?

where a virus is carried by an organism, and it can go from that organism to another host

Do all microorganisms cause diseases ?

no

Do microorganisms evolve and adapt to hosts?

yes

When pathogens switch hosts. the outcome is _______ (unpredictable/predictable)

Unpredictable

CFRs can influence perception of risk versus hazard (T/F)

T

- CFRs are rarely uniform across all strata of the population (T/F)

T

- CFRs depend on methods used to record death and diagnosis. Therefore they are estimates (T/F)

T

Can the roles of the immune system be not beneficial to us?

Yeah. As seen in graft rejection, transplants, metabolic diseases

What are the 4 means of barrier defence mechanisms?

Skin

Gut

Lungs

Eyes/nose/oral cavities

What are cathelicidins?

a group of antimicrobial peptides that are part of the innate immune system in many vertebrates.

Where are cathelicidins found?

Skin, Gut, Lungs

Does innate immunity have broad specificity?

Yes

Does innate immunity recognise danger signals?

yes

Is innate immunity ready to go?

Yes

Does innate immunity give time for the adaptive immune response to develop?

yes

If there is no innate immunity, what is seen?

No response to infection

Does innate immunity recruit immune cells to infection sites

yes

What are the 4 innate killing mechanisms?

Phagocytosis

Secretion of cytotoxic granules

Killing of infected cells

Complement proteins

Is Adaptive immunity highly specific?

yes

Does adaptive immunity take time to develop>

yes

Does adaptive immunity remember pathogens?

yes

What type of cells are seen in adaptive immunity?

T and B cells

What is the function of Helper T cells?

promotion of B-cell and T-cell activity

What is the function of Regulatory T cells?

Regulates response levels against a pathogen. Signals to stop overreacting

What is the function of cytotoxic T cells?

KILL KILL KILL

If there is no adaptive immunity, what happens?

Infection persists but there is some defence seen from innate immunity

What are the 3 communicators covered in the lectures between innate and adaptive immunity?

Cytokines

Cell to cell communication

Lymph nodes/spleed

Does lymph nodes and spleen play an important role in adaptive immunity responses?

yes. They are the chilling spot for the adaptive immunity cells

What are cytokines?

chemical messengers produced in response to a stimulus

Can cytokines act locally and systematically?

yes

Innate cells recognise generic danger signals via what receptor

pattern recognition receptor

Does somatic recombination help recognise diverse antigens?

yes

Explain the working of the alternate pathway in the complement system

C3 protein (the precursor) forms C3b, that binds to amino and hydroxyl groups on the surface of the bacterium

In the lectin pathway ______ binds to mannose in the surface of the bacterium

MBL (mannose binding lectin)

What are PAMPs?

pathogen associated molecular patterns. Conserved microbial molecules that are shared in all microbes

What are PRRs?

pattern recognition receptors. Receptors that recognise PAMPs and DAMPs

What are DAMPs?

damage associated molecular patterns. Released from dying cells, indicating tissue damage

What are the key immune cells in Innate immunity?

Macrophages

Dendritic cells

Neutrophils

NK cells

function of macrophages?

detect infections and initiate responses

function of dendritic cells?

Present antigens to T cells

What is the function of neutrophils?

phagocytosis

What is the function of NK cells

apoptosis

What is the function TNF-alpha of cytokines?

signals inflammation, attracts macrophages, recruits more B cells and other T cells

What is the function of interferon-gamma

activates macrophages by producing NK cells

NK cells produce what?

cytokines

During the resting stages what do innate immune cells do?

sample the environment through phagocytosis, normal tissue maintenance

What do annoyed innate immune cells do?

respond to DAMPs and prepare for WARRRRRRRRRRRRRRRR

What do angry innate immune cells do?

WAGE WAR ON THE ENEMIES (foreign particle) !!!!!!!!!!!!!!!!

What is sepsis?

uncontrolled immune response to a systemic infection

Excessive TNF-alpha causes? 3

organ damage, septic shock, bp drops

What are the types of adaptive immune cells in the body?

B and T cells

What are the 3 kinds of T cells?

Cytotoxic T cells

Helper T cells

Regulatory T cells

What is an antigen?

molecule recognised by the adaptive immunity

What is an epitope?

A small site of recognition on a large molecule that an antibody recognizes.

What is a paratope?

part of the antibody that binds to the antigen

What kind of things do B cells recognise?

Pretty much anything organic/ some inorganic too

What kind of things do T cells recognise

Processed information from the APCs

What are APCs?

antigen presenting cells

What cells are APCs?

macrophages, dendritic cells, B cells

APCs present processed antigens via ______ molecules

MHC (Major histocompatibility complex)

How many antigen binding sites do B cells have?

2

How many antigen binding sites do T cells have?

1

Antigen binds to antibody via _________ (non-covalent/covalent) interactiions?

non-covalent

What are the segments that can undergo somatic recombination in the light chain?

VJ

What are the segments that can undergo somatic recombination in the heavy chain?

VDJ

What are the 3 ways in which junctional diversity helps in generative receptor diversity?

Random nucleotide insertions

Random hairpin structures

VDJ recombination

What is allelic exclusion?

when only one of the parental alleles that code for the TCR or B-cell receptor is functional, ensureing only one receptor specificity per B or T cell by shutting down rearrangement once a successful receptor is produced.

What is clonal expansion?

an increase in the number of cells by mitotic cell division

What is antigenic drift?

gradual accumulation of mutations

What is antigenic shift?

Major antigen changes due to gene exchange (e.g., flu pandemics).

What are the 4 ways pathogens evade immune memory?

Antigenic drift

antigenic shift

high mutation rate

antigen switching

Where are T cells produced?

thymus

Where are B cells produced?

bone marrow

What are the two classes of MHC?

Class I and Class II

What antigens do MHC I recognise?

intracellular antigens

What antigens do MHC II recognise?

intercellular

What cells are MHC 1 found in?

all nucleated

What cells are MHC2 found in?

APCs

CD8 is present in which MHC class?

1

CD4 is present in which MHC class?

2

Which MHC detects longer amino acids?

2

Cytotoxic T cells detect which MHC class?

1

Helper T cells detect which MHC class?

2

Does the MHC contain a processed part of the antigen when binding to the TCR?

yeah

do high variability in MHC alleles ensures a broad range of peptide presentation.

yeah

- T cells attack grafts with unmatched MHC molecules, leading to _______ (I should know this without fail)

Graft rejection (happens a lot)

Explain the life phases of dendritic cells (HARD but lowkey easy)

Sampler Phase:

- Takes up molecules via phagocytosis.

- Expresses PRRs to detect DAMPs/PAMPs.

Traveller Phase:

- Samples the infection site, then stops sampling to prevent picking up self-antigens.

- Migrates to lymph nodes (LNs) with captured antigens.

Presenter Phase:

- Mature antigen-presenting cell in LNs.

- Upregulates MHC Class II and costimulatory molecules B7 (CD80/CD86).

How do T cells know if its food or a deadly life threatening disease that can cause havoc on the physical body?

MHC-peptide-TCR complex verifies antigen specificity

PAMPs/DAMPs cause up regulation of B7 that binds to the CD28 receptor in T cells that actually conveys if it is dangerous

What is the role of macrophages as an APC?

present antigen to T cell,

Requires T cell's help to activate more macrophages though (IFN-gamma)

What is the role of B cells as APCs?

Require T cell "permission" to activate and differentiate

it has a T-dependent and T-independent antibody responses.

What is the function of Cytokine IL-10?

it is an inhibitory cytokine