Immunology Flashcards by First Last

Innate Immunity

Natural immunity that is present from birth and is generally non-specific and fast

Includes physical barriers, inflammatory mediators, complement proteins, acute phase proteins, immune cells

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What does the immune system do

identifies and eliminates microorganisms by distinguishing self molecules from non self molecules and identifying danger signals

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ways to manipulate the immune system to prevent or treat human disease

immunisation
anti-inflammatory and immunosuppressive drugs
cancer immunotherapy

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barriers to infection - skin

physical barrier - tightly packed, highly keratinised cells,

physiological factors - low pH (5.5), low oxygen tension

sebaceous glands - hydrophobic oils, lysozymes, ammonia

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Tell me about mucus

Mucous membranes line all body cavities that are in contact with the external environment

Mucus traps bacteria and contains lysozymes and defensins that directly kill invading pathogens

Secretory IgA

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tell me about commensal bacteria

Compete with pathogens for resources and produce fatty acids and bactericides that stop pathogens growing

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What are cytokines

Interferons released by virally infected cells signal to neighbouring uninfected cells :

destroy RNA and reduce protein synthesis and undergo apoptosis

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What do interferons activate

immune cells e.g. NK cells

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What are acute phase proteins

Proteins produced by the liver whose plasma concentrations increase or decrease in response to inflammation

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What are examples of acute phase protiens

C3 - complement system protein
MBL - complement system protein
CRP - activates complement via classical pathway

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What is transendothelial migration

the recruitment of neutrophils to the site of infection/damage during acute inflammation

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What are the stages of transendothelial migration

Loss of intravascular fluid in the presence of inflammation causes slower blood flow, allowing neutrophils to undergo margination (neutrophils travel close to endothelial cells instead of centre of the vessel)
Neutrophils can then encounter and bind to adhesion molecules expressed by the endothelial cells
Neutrophils migrate across the endothelium via diapedesis
Once in the tissues, the neutrophils travel to the exact site of injury via chemotaxis
Neutrophils are then activated by PAMPs and pro-inflammatory mediators such as TNFa

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What are types of killing mechanisms

NETs
Phagocytosis
Degranulation

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Tell me about NETs

neutrophil extracellular traps : release of a net-like structure that traps pathogens, leading to phagocytosis

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Tell me about phagocytosis

Pathogens release chemical signals that attract neutrophils, which use PRR to bind to and phagocytose these pathogens

Kills internalised pathogens via 2 distinct mechanisms : phagolysosomal killing and ROS-dependent killing

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Tell me about degranulation

release of anti-bacterial granules leading to direct damage and systemic inflammation

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What are the modes of ingestion

Receptor mediated endocytosis

Pinocytosis

Phagocytosis

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Tell me about receptor mediated endocytosis

molecules bound to membrane receptors are internalised

important in the generation of adaptive immunity

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Tell me about pinocytosis

ingestion of fluid of surrounding cells

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Are macrophages a phagocytic cell

Yes

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what is macrophages phagocytosing bacteria facilitated by

opsonization

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What is opsonisation

the coating of pathogens by soluble factors (opsonins) to enhance phagocytosis

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What are the stages of phagocytosis

PRRs on macrophages bind to PAMPs on pathogen which signals the formation of the phagocytic cup
Cup extends around the pathogen and pinches off - phagosome
Phagosome fuses with lysosome - phagolysosome
Pathogen killed and contents degranulated n
Debris released into extracellular fluid
Pathogen-derived peptides expressed on special cell surface receptors (MHC-II)
Pro-inflammatory mediators released (TNFa) - acute inflammation

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What are examples of opsonins

C3b
C-reactive protein (CRP)
IgG/IgM

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Are dendritic cells phagocytic cells

yes

What do dendritic cells do

act as a bridge between the innate and acquired immune system express antigens on their cell surface and present them to T cells

What are eosinophils associated with

allergy

Tell me about basophils

Granules contain histamine etc. act as effector cells in allergic reactions

What do mast cells deal with

pathogens too large for phagocytosis

What are mast cells associated with

Allergy

What is gene expression

Production of new pro-inflammatory substances e.g. leukotrienes and prostaglandins

What can immune systems be enhanced by

antibodies

What is acquired (adaptive immunity)

Immunity that is not present from birth Is specific and slow

What is acquired (adaptive) immunity induced by

foreign material

Is acquired immunity able to discriminate between self and non-self

Yes

What does acquired immunity include

cytokines, antibodies, B and T cells

The complement system, when activated, creates a cascade of chemical reactions that promotes:

opsonisation of pathogens direct pathogen killing accute inflammation leukocyte recruitment

Where are low levels of inactive complement system proteins normally found

plasma and extracellular fluids

Go and learn the complement system pathways

NOW!!!!

Where do B cells mature

in the bone marrow

What are B cells important in

humoural immune response

What do B cells produce

antibodies that attack pathogens circulating in the blood and lymph

B cells play a key role in defence against ...

extracellular pathogens

What do B and T cells normally circulate around

their primary lymphoid tissue (site of development) in their inactive form

What activates the B and T cells and where

Antigen presentation in the secondary lymphoid tissue (lymph nodes, spleen, MALT)

B cell activation : what do membrane-bound antibodies on the B cells bind to

target antigen IgM (or IgD)

Why are neutrophils much better killers than macrophages

Because they have a 2nd way to kill internalised pathogens

How many signals to B cells require to become fully active

Once activated, what do B cells become

plasma cell (antibodies) or a memory B cell

What is generated in B cell activation

IgM and IgG

Tell me about the transport of lymphocytes

Lymph and Lymphocytes leave lymph node, medullary sinus, efferent lymphatic vessels, blood circulation via lymphatic ducts at the subclavian vain

What is Ig

immunoglobin

What are antibodies made up of

2 light chains and 2 heavy chains

Where are membrane bound antibodies located

surface of B cell

what is agglutination

the action of an antibody when it cross-links multiple antigens producing clumps of antigens

what does agglutination do

enhance phagocytosis prevents viruses from binding to and infecting host cells

What is the first antibody to be made in an infection

IgM

When is IgM a monomer/pentamer

Monomer when bound to B cell membrane Pentamer when released into plasma

What are the functions of IgM

B cell activation, agglutination, complement system activation through classical pathway

What is the most abundant antibody in the plasma

IgG

Is IgG a monomer or pentamer

Monomer

What are the functions of IgG

foetal immunity (placental transfer)

What is the second most abundant antibody

IgA

What are the functions of IgA

neonatal defense (found in breastmilk)

What are IgE produced in

allergic response

Where to T cells mature

thymus

What can T cells recognise

peptide antigens

What are regulatory T cells involves in

lymphocyte suppression

What are memory T cells involved in

the adaptive immune response

Tell me about CD4+ Helper T cells

activate B cells and stimulate production of memory B cells

Tell me about CD8+ killer T cells

kill infected cells

What can T cells only recognise

peptide antigens that are presented to their TCR by MHC molecules

Tell me about Class I MHC

expressed on all nucleated cells present peptide antigens to CD8+ killer T cells

Tell me about Class II MHC

expressed only on antigen presenting cells (e.g. dendrites, macrophages), present peptide antigens to CD4+ helper T cells

What are hypersensitivity reactions

Immune response that results in bystander damage to the self usually exaggeration of normal immune mechanisms

Type 1 hypersensitivity reaction

immediate hypersensitivity

Type 2 hypersensitivity reaction

direct cell effects

Type 3 hypersensitivity reaction

immune complex mediated

Type 4 hypersensitivity reaction

delayed type hypersensitivity

Are most complex diseases one or a combination of the types of hypersensitivity

combination

what is a classical type of type 1 hypersensitivity (immediate)

allergy, mediated by the inappropriate production of specific IgE antibodies to harmless antigens

What are the cells involved in type I hypersensitivity reactions

Mast Cells, B Cells, Eosinophils

Children who produce more Th2 ...

are more likely to develop allergens than children who switch to producing Th1

take a minute to breath

a whole minute!!!

Tell me about the management of IgE mediated allergic disorders

Avoidance of allergen Block mast cell allergen - medication Prevent effects of mast cell activation - anti-histamines Anti-inflammatory agents - removes Th2 cells Adrenaline - epi-pen

What is type II hypersensitivity reactions (direct cell effects) mediated by

IgM/IgG antibodies bind to antigens present on cell surfaces or ECM. this marks the cell for destruction

Type IIa reactions

destruction of antigen-positive cells

Type IIb reactions

stimulation of cell surface antigens

Tell me the summary table (because you lazy) of the 4 types of hypersensitivity reactions

Type 1 - antibody mediated immunity, IgE, Fast response (minutes), allergic reactions, asthma/allergic rhinitis Type 2 - antibody mediated immunity, IgG/IgM, Intermediate, body cells directly attacked by antibodies, Rheumatic heart disease Type 3 - antibody mediated immunity, IgG/IgM, intermediate, complex accumulation and destruction, rheumatoid arthritis Type 4 - cell mediated immunity, Th1, late response (48-72 hours), cell mediated cytotoxicity, transplant rejection/contact dermatits

Tell me about resolution

normal immune response pathogen cleared tissure repair

Tell me about the response to a latent infection

normal immune response pathogen controlled infection can re-occur

Tell me about the response to chronic infection

Defective immune response Pathogen not cleared or controlled

What are primary immunodeficiencies a result of

genetic defects

What are secondary immunodeficiencies caused by

environmental factors, such as HIV or malnutrition

What does SPUR stand for - PRIMARY IMMUNE DEFICIENCY

Serious infections, persistent infections, unusual infections, recurrent infections

Are serious infections responsive or unresponsive to oral antibiotics

unresponsive

What are other features that suggest primary immune deficiency

Weight loss severe skin rash chronic diarrhoea cancer family history