*Immunology 1 (lectures 1 and 2) Flashcards
SCID?
What is it?
Severe combined immunodeficiency
Severe abnormalities of the immune system
5 things caused by the immune system going wrong?
Cancer recurrent infections Transplant rejection Allergies Autoimmune disease
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
What exists between pathogens and hosts
Evolutionary arms race
Where do pathogens infect the body through?
Mucosal surfaces (airway, GI tract, repro. tract) External epithelia (wounds, insect bites, etc.)
5 components of the body that protect against infection?
Lymph nodes Spleen Lymphatics Bone Marrow Skin
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))
What does mucous line
All cavities that come into contact with the environment e.g. resp, GI, urogenital
How does mucous prevent infection?
Physical barrier
contains IgA
contains enzymes (lysozyme, defensins)
Contains lactoferrin (starves invading bacteria of iron)
what do cilia do
Directly trap pathogens
aid in the removal of mucous
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
What is bactericidin
An antibody that causes complement dependent lysis of bacteria
What does eradication of normal flora by board spectrum antibiotics often cause?
Opportunistic infection
Probiotics
Live bacteria and east that are good for your health
Immune system?
Network of specialised cells, tissues and soluble factors that co-operate to kill and eliminate disease-causing pathogens and cancer cells
4 classes of pathogen
Extracellular bacteria, parasites, fungi
Intracellular bacteria, parasites
Viruses (intracellular)
Parasitic worms (Extracellular)
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
Complement system
Family of approx. 30 different proteins
Where is complement produced?
In the liver
What do antibodies provide defence against?
Extracellular pathogens and toxins
Where do complement proteins become activated?
infected/ inflamed tissues
What do complement proteins have the ability to do?
enzymatically cleave and activate other downstream complement proteins in a biological cascade
Name for chemical messanger
cytokine
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
