*Immunology 1 (lectures 1 and 2) Flashcards by B -

SCID?

What is it?

Severe combined immunodeficiency

Severe abnormalities of the immune system

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5 things caused by the immune system going wrong?

Cancer
recurrent infections
Transplant rejection
Allergies
Autoimmune disease

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6 causes of emergence of new infections?

Global village
population growth
change in human behaviour
changes in dynamic of other infections 
loss of natural habitat
Interactions of pathogens with humans e.g. resistance

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What exists between pathogens and hosts

Evolutionary arms race

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Where do pathogens infect the body through?

Mucosal surfaces (airway, GI tract, repro. tract)
External epithelia (wounds, insect bites, etc.)

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5 components of the body that protect against infection?

Lymph nodes
Spleen
Lymphatics
Bone Marrow
Skin

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How does the skin protect against infection?

Physical barrier (highly packed, highly keratinised, multilayered cells)
Physiological barrier (low pH (5.5), low O2 tension)
Sebaceous glands (secrete hydrophobic oil, lysozyme (destroys bacterial cell wall), ammonia (anti-bacf. properties), defensins (anti-microbial peptides))

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What does mucous line

All cavities that come into contact with the environment e.g. resp, GI, urogenital

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How does mucous prevent infection?

Physical barrier
contains IgA
contains enzymes (lysozyme, defensins)
Contains lactoferrin (starves invading bacteria of iron)

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what do cilia do

Directly trap pathogens

aid in the removal of mucous

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How does commensal bacteria help to prevent infection?

Competes with pathogenic microbes for scarce resources
Produces fatty acids and bactericidns
reduce pH in large bowel
Synthesise vitamin K and B12

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What is bactericidin

An antibody that causes complement dependent lysis of bacteria

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What does eradication of normal flora by board spectrum antibiotics often cause?

Opportunistic infection

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Probiotics

Live bacteria and east that are good for your health

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Immune system?

Network of specialised cells, tissues and soluble factors that co-operate to kill and eliminate disease-causing pathogens and cancer cells

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4 classes of pathogen

Extracellular bacteria, parasites, fungi
Intracellular bacteria, parasites
Viruses (intracellular)
Parasitic worms (Extracellular)

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See mind map study material for info about components of the immune system

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Antigen

Any substance that can stimulate an immune response

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Complement system

Family of approx. 30 different proteins

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Where is complement produced?

In the liver

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What do antibodies provide defence against?

Extracellular pathogens and toxins

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Where do complement proteins become activated?

infected/ inflamed tissues

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What do complement proteins have the ability to do?

enzymatically cleave and activate other downstream complement proteins in a biological cascade

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Name for chemical messanger

cytokine

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Summarised role of cytokines

co-ordinates the immune system

4 examples of cytokines?

Interferons, tumour necrosis factor, chemokines, interleukins

Interferons?

Anti-viral activity

Tumour necrosis factor

Pro-inflammatory cytokine

Chemokines?

Control and directs cell migration

Interleukins

Various functions e.g. inflammatory mediator, stimulate T lymphocytes to become NK cells

Phagocytic cells?

Monocytes, macrophages, neutrophils (ingest bacteria and fungi and clear debris from the body

What is an important source of cytokines which regulate acute inflammatory response?

Phagocytic cells

Where do monocytes differentiate into macrophages

in peripheral tissues

what are macrophages

Long lived tissues resident phagocytes

What are the functions of macrophages

to clear cellular debris and engulf and kill pathogens

Where are kupffer cells located and what is their function

Liver | RBC breakdown

Location of alveolar macrophages

lung alveoli

location of mesangial cells

kidneys

location of microgal cells

CNS

Additional functions of macrophages (3)

limit inflammation involved in tissue repair and wound healing involved in antigen presentation

Other name for neutrophils | Half life

Polymorphonuclear cells | Less than 6 hours (short)

Where are neutrophils found?

Circulate the blood and are rapidly recruited into inflamed, damaged and infected tissues

How do dendritic cells work?

Present in peripheral tissues where they are in an immature state They phagocytose an antigen Then mature and migrate into secondary lymphoid tissue where they play a key role in antigen presentation

Which carries out more killing and degradation compared to antigen presentation, neutrophils or macrophages?

Neutrophils

Where are mast cells found? | Purpose?

In tissues | protect mucosal surfaces

Where are basophils and eosinophils found

circulate in blood and are recruited to sites of infection inflammatory signals

What do basophils and eosinophils do (3)

Release chemicals such as histamine, heparin and cytokines producing acute inflammation Defence system against large pathogens that cannot be phagocytosed e.g. parasitic worms key role in mediating allergic responses

Are NK cells part of the innate or adaptive immune system

Innate

What are NK cells

Large granular lymphocytes

What can NK cells do?

Kill tumour cells and virally infected cells, can also kill antibody-bound cells and pathogens

Where are B and T cells found?

Constantly circulating through the blood, lymph and secondary lymphoid tissues

When are t and b cells activated

When they meet a pathogen/ antigen

What are B cells responsible for

The production and secretion of antibodies to defend against extracellular pathogens

What type of pathogens do T cells defend against?

Intracellular pathogens (viruses, mycobacterium)

Types of T cells and role

Helper T cells (key immune system regulators) | Cytotoxic T cells (kill virally infected body cells)

What is immunological memory

Once the adaptive immune system has recognised and responded to a specific antigen, it exhibits life-long immunity to this antigen (mediated by memory T cells and B cells)

Innate immune system?

Rapid (mins-hrs), general response to many different pathogens

Adaptive immune system

slow (days), unique response to each individual pathogen mediated by T and B lymphocytes and responsible for generating immunological memory

What is primary lymphoid tissues?

Sites of leukocyte development

What are secondary lymphoid tissues?

Sites where adaptive immune responses are initiated (contain T cells, B cells and dendritic cells

What is the lymphatic system?

System of vessels draining fluid from body tissues - lymph nodes are positioned regularly along lymph vessels (trap pathogens and antigens in lymph)

What is lymphoedema?

Condition of localised fluid retention and tissue swelling caused by a compromised lymphatic system, which normally returns interstitial fluid to the thoracic duct and then the bloodstrem

Causes of lymphoedema?

Inherited Cancer treatments Parasitic infections