Topic 9 Flashcards
active immunity
- involves production of antibodies by person in response to pathogen
- b and t memory cells are produced
- can be natural or acquired
natural active immunity
- acquired when person comes into contact with particular pathogen for firs time
- activates immune system to produce antibodies and b/t memory cells to specific pathogen
artificial active immunity
results from vaccination
- body is injected with disabled pathogen or its toxin
- vaccines prepared using dead or attenuated pathogens
- antigens are still present- trigger immune response of person injected wit pathogen
why are vaccines used
to activate immune system to produce antibodies against specific pathogens without actually causing disease
vaccines
- killed/inactivated vaccines produce weaker immune response compared to live attenuated vaccine- lasts for shorter period
- killed/activated vaccines have to be injected more than once
- when vaccine first injected- primary antibody response occurs
- second vaccination -secondary antibody response
- antibody produced is specific to pathogen in vaccine
herd immunity
-indirect protection of populations from infection where that protection is created by presence of immunised individuals in population- protection received by those unvaccinated
-reduced number of infected individuals- less hosts so less likely disease will spread
-only effective when huge proportion of population has immunity
applied to only infectious diseases
-herd immunity protects vulnerable e.g elderly, new borns
passive immunity
- antibodies produced in one person/organism and introduced into another can react with antigens to provide immunity
- can be acquired naturally or induced
- -advantage-provides immediate protection to person receiving antibodies
- disadvantage- short lived as person injected with them did not produce them- did not produce memory cells
naturally passive immunity
- occurs when developing foetus receives maternal antibodies across placenta
- baby acquires antibodies through mothers breast milk
artificial passive immunity
- occurs when person is injected with antibodies
- antibodies obtained through blood plasma of donors
- or extracted from other organisms
failures in immune system
autoimmune disease
allergies
immunodeficiency disease
cancer
autoimmune disease
- ability to recognise self from non self sometimes breaks down
- if happens, body acts as if own cells are non-self
- b cells produce antibodies and t cells attack and destroy self cells like they attack invading microbes
- results in autoantibody production- autoimmune disease
why do autoimmune diseases occur
-infection with pathogen displaying antigens similar to antigen molecules on surface of body cell- results in production of antibodies/activation of t cells- ultimately leads to pathogen destruction as well as body displaying that antigen on cell membrane
allergies
- present when immune system reacts abnormally to substances in environment that are harmless to most people
- involve cells of both innate and adaptive immune system
components of immune system that produce allergic response
mast cells which release histamines-cause symptoms or allergies
IgE antibodies
allergic reaction
b cell makes initial contact with allergen
plasma cell then releases IgE antibodies
-IgE receptors on mast cell membrane come into contact with IgE antibodies
-on subsequent contact with allergen, it binds to mast cell with specific IgE antibodies
-mast cell releases histamines causing an allergic reaction
immunodeficiency diseases
- malfunction or deficiency in or more components of immune system
- may be inherited
- immune system fails to produce antibodies and person lacks immunity
cancer
- normal cells undergone transformation, divide uncontrollably and possess tumour associated antigens- mark them as non self
- Tc cells recognise non-self and destroy cancerous cells
- sometimes tumour cells shed antigens- evading recognition by immune system
monoclonal antibodies
identical antibodies produced by clone of cells that have high specificity to their targets
- drugs used in treatment of cancer
- specially designed antibodies- every antibody in the set binding to same antigen
- can design antibodies that target specific antigens on cancer cells- make multiple copies in lab
- can be divided into naked or conjugated
- naked have no other molecules
- conjugated have additional group attached
naked monoclonal antibodies
- stop growth of new blood vessels to cancer cells
- signal immune cells to attack cancer
- block signals for cell division
conjugated monoclonal antibodies
-deliver anti-cancer drug and radio-isotopes to cancer
blood group antigens
-red blood cells have antigens on surface
-antibodies flow in plasma without prior contact to foreign antigen
ABO and rhesus blood group antigens are bet known
ABO blood system
blood A- has B antibodies- has a antigens
blood b- has a antibodies- has b antigens
blood ab- has no antibodies- a and b antigens- can receive form any- no antibodies- can only give to ab
blood o- has a and b antibodies-no antigens- can give to any- not antigens-
rhesus blood system
rh+ has rh
rh- lacks rh
rhesus incompatibility
blood group of pregnant woman is incompatible with baby
- if rh of baby is different from mother, haemolytic disease is suffered by newborn
- blood of foetus and mother are kept separate by placenta- only antibodies can cross placenta
organ/tissue rejection
- dealt with by cell mediated response
- after recognition of non-self cells- Th cells activate Tc cells and or NKC
- cytotoxic chemicals such as perforins are produced- destroy foreign cells
- macrophages engulf and destroy foreign cells
