Immune Response Flashcards
Describe non-specific responses
Responds to all pathogens in the same way
Act immediately
Barrier to block pathogens
Give an example of a non-specific in the body
Phagocytosis
What do tears contain?
Salt and lysozome that kills microbes
Whyat do eyelashes prevent?
Dust/dirt from getting in the eye
What does our skin act as?
Outer layer acts as a tough barrier
What does the hair follicles on the skin make?
Sebum (oily substance)
What does the nose contain to stop pathogens from getting in?
Hairs and mucus
What does the blood contain that is a non-specific response?
Phagocytes and platelets
What does the stomach contain that kills microbes?
Acid
What makes the mucus in the trachea?
Goblet cells
Why is mucus good in the lungs?
Becasue it prevents microbes from getting in
Why must lymphocytes recognise between self and non-self material?
Or they would destroy your own tissue
What do cells all have to prvent lymphocytes from destroying self material?
Specific molecules on their surface
Why is there a huge variety of cell markers?
Huge range of amino acids
Have a highly specific tertiary structure
Gives them a variety of specific 3D structures
Allows one cell to be distinguished from another
What do antigens do?
Trigger an immune response
Name some antigens
Glycoproteins
Polysaccharides
Lipids
Nucleic acid
What do antigens allow the immune system to identify?
Pathogens
Non-self material
Toxins
Abnormal body cells
What is the advantage of antigens?
It allows rapid recognition of these cells, which allows them to be dealt with effectively
What is the disadvantage of antigens?
Transplant patients may have the transplanted organ rejected because the immune systme recognises it as non-self
How do you minimise the risk of the organ being rejected?
Donor tissues are closely matched
Immunosuppressant drugs are given to reduce immune response
Where are adult lymphocytes produced?
Bone marrow
What ahppens to lymphocytes that produce an immune response to self material?
Apoptosis (programmed cell death)
When must apoptosis happen before and why?
Before they differntiate into mature lymphocytes to prevent them appearing in the blood
Why are infections rare before birth?
Due to the placenta and mother’s defences
In the fetus what are lymphocytes constanly colliding with?
With other body cells
What do lymphocytes collide exclusively with?
Body’s own cells as they have protein receptors that match the body’s own cells
Why do lymphocytes die/ be suppressed?
So that the only ones at birth fit non-self material
What is the first step of phagocytosis?
Phagocyte detects chemicl products of pathogen
What are the chemical products called produced by the pathogen?
Chemoattractants
What is the second step of phagocytosis?
Phagocyte comes into contact with the pathogen and the recpetors on the phagocyte’s surface attacks the chemicals on the pathogen’s surface
What is the third step of phagocytosis?
Phagosome is formed by engulfing the bacterium
and the lysosomes inside the phagocyte move towrds the phagosome
What is the fourth step of phagocytosis?
Lysosomes release lysozymes into the phagosome and hydrolyses the bacterium
What is the fifth (final) step of phagocytosis?
Hydrolysis products of bacterium are absorbed by the phagocyte
What is infection?
The interaction between the pathogen and the body’s various defense mechanisms
What is immunity?
The abilty to resist infections by protecting agaisnt pathogens or their toxins that have invaded the body
What is an antigen?
A molecule that is recognised as non-self by the immune system which triggers an immune response
Describe specific responses
Reacts to specific antigens
Response is slower but provides long term immunity
Requires lymphocytes
Where are T lymphocytes matured?
Thymus gland
What do T cells provide?
Cell mediated immunity
What do T cells respond to?
Antigens presented on body cells (not fluids)
Foreign material inside the body
Own cells altered by virusses/cancer or transplanted tissue
What are cells called that display foreign antigens?
Antigen presenting cells
What do receptors on each Tcell respond to?
A single antigen
Describe how Tcells work
Pathogen inavde body + taken in by phagocytes
Phagocyte places antigens from pathogen on its surface
Receptors on T H cells fit onto these antigens
Activates other Tcells to divide rapidly by mitosis + form clone
What do cloned Tcells develop into?
Memory cells
Why are memory cells important?
Allow fast future response to the same pathogen
What do cloned Tcells stimulate?
Phagocytes to engulf pathogens
Bcells to divide + secrete antibodies
What do cloned Tcells activate?
Cytotoxic Tcells (Tc cells)
What are the 4 ways help Tcells to distinguish between these and own cells?
Phagocytes present antigens
Body cells present viral antigens
Cancer cells look different + present antigens
Transplanted cells have different antigens
What does HIV stand for?
Human immunodeficiency virus
What does AIDS stand for?
Acquired immunodeficiency syndrome
How did HIV arise?
It jumped the species barrier - transferred from primate to human
Due to eating or slaughtering chimpanzees
What are the ways HIV is transferred?
Sexual intercourse Drug-taking using infected needles Blood infection of wounds Blood transfusions Mother to child across the placenta + via breast milk
What are the symptoms of HIV?
Fever Sore throat Body rash Tiredness Joint pain Muscle pain Swollen glands (nodes)
What are the symptoms of AIDS?
Weight loss Chronic diarrhoea Night sweats Skin problems Recurrent infections Serious life threatening illness
What is reverse transcriptase?
Enzyme that catalysed the production of DNA from RNA
What does it mean that HIV uses reverse transcriptase?
This means it is a retrovirus
How many T helper cells do healthy people have?
800-1200
How many T helper cells does AIDS suffers have?
<200
Since people with AIDS do not have enough T cells what does this mean?
B cells can’t be stimulated
Cytotoxic T cells cannot be activated
Memory cells are infected + destroyed
Does HIV cause death?
No the secondary illnesses do
Why do antibiotics not destroy viruses?
As they don’t have a metabolic pathway so there is nothing for the antibiotic to disrupt
Why do they use antibiotics to treat bacteria?
Bacterial cells have cell walls made of murein
Murein is tough and not easily stretched
Water enters by osmosis
Which weakens the wall
Causes them to burst
What do B cells respond to?
Foreign material outside of body cells
Where do B cells mature?
Mature in bone marrow
What type of immunity do B cells lead to?
Humoral immunity
What are B cells soluble in?
Blood and tissue fluid
Describe how B cells work
Surface antigens taken up by B cells
B cells process + present them on their surface
T cells attach to processed antigens on B cells
Activates B cells
Divide by mitosis
THEN TWO ROUTES
Why is reinfection unlikely?
Due to memory cells
Why does reinfection sometimes occur?
Because diseases have many different strains
What is called when antigens constantly change?
Antigenic variation
What does the body have to do when antigenic variation occurs?
Start from scratch with primary response
As antibodies are no longer complementary
So you develop symptoms
What is a monoclonal antibody that kills cancer cells?
Herceptin
What cancers does herceptin kill?
Ovarian and breast
How does herceptin kill cancer cells?
Blocks immediate growth signal and marks cancer cells for destruction
What is the advantages of using monoclonal antibodies to destroy cancer cells?
It doesn’t target other body cells
What does indirect monoclonal antibodies therapy do?
Attach radioactive or cytotoxic
How do pregnancy tests work?
hCG hormone released into urine
hCG attaches to antibody joined to coloured marker
hCG-Ab-coloured complex is trapped by another Ab causing coloured line to appear
hCG-Ab-complex moves up the strip by diffusion
What is the Elisa test?
A test that uses antibodies to detect the presence + amount of protein in a sample
What is the enzyme in the Elisa test linked to?
Immunoasorbant assay
What is the first step of the Elisa test?
Apply sample to surface
Antigens in sample attach to surface
WASH to remove any antigens that have not attached
What is the second step of the Elisa test?
Add antibody that is specific to antigen you’re trying to detect
Leave to bind
RINSE to remove excess antibody
What is the third step of the Elisa test?
Add second antibody that binds to first antibody
Second antibody has enzyme attached
WASH to remove excess antibody
What is the final step of the Elisa test?
Add substrate (colourless) Enzyme acts on substrate Substrate converted into coloured compound Colour= positive test
What is the prostate specific antigen?
Protein produced in prostate cancer
Where are levels of PSA detected?
The blood
How are monoclonal antibodies used in the treatment of PSA?
Antibodies interact with PSA
Measuring levels of antibodies allows you to estimate levels of protein present
What are the ethical implications of monoclonal antibodies?
Use mice to generate antibodies + tumour cells
Deaths associated with antibodies
Drug testing can have high risks
Do antibodies directly destroy antigens?
NO
What is the structure of an antibody?
Antigen binding site Variable region Constant region Heavy + short chains Receptor binding site
How many polypeptides does an antibody have?
4
What is each binding site on an antibody complementary to?
A specific antigen
What does it form when an antibody joins to an antigen?
Antigen-antibody complex
What are poly clonal antibodies?
When each B cell divides to produce different antibodies
What is a monoclonal antibody?
When a single type of antibody is cloned
What are the two routes that B cells can take?
Primary and secondary response
What is the primary response of B cells?
Cloned plasma cells produce antibodies complementary to antigens
Antibody attaches to antigen and destroys pathogen
What is secondary response of B cells?
Some B cells remain and become memory cells
Where do plasma cell secrete antibodies?
Into blood plasma
How long can plasma cells survive for?
Only a few days
How fast can plasma cells produce antibodies?
2000 antibodies/sec
What do plasma cells destroy?
Pathogens + toxins
What type of defence is a plasma cell?
Immediate defence
What type of response is a plasma cell?
Primary response
How long do memory cells survive for?
Decades
Where do memory cells live?
Blood and tissues
What type of immunity do memory cells provide?
Long term immunity
Do memory cells produce antibodies directly?
NO
Are memory cells better than plasma cells?
Yes because they are faster and more intense
What type of response is a memory cell?
Secondary response
What do memory cells allow your immune system to do?
Fight infection before any symptoms occur
What are the two forms of immunity?
Passive
Active
What is passive immunity?
Antibodies introduced from outside source
What is an example of passive immunity?
Anti-venom
Immunity acquired by a fetus from the mother
Is passive long term?
NO since no primary or secondary immune response
What is active immunity?
Production of antibodies stimulated by individuals
Is active long term?
YES
How does active immunity happen?
Direct contact with antigen
What are the two types of active immunity?
Natural
Artificial
What is natural active immunity?
Individual infected with a disease
What does natural lead to?
Normal immune response
What is artificial active immunity?
Vaccination
What artificial lead to?
Induced immune response
What are the ethics to do with vaccinations?
Animals used in development
Side effects
Who should it be tested on?
Compulsory?
Is it fair to test where target disease is common?
Should expensive programme continue for nearly eradicated diseases?
How do you make vaccinations successful?
Cheap Few side effects Administrated correctly at one time Ability to produce, store + transport vaccine Vaccinate majority of population
What is herd immunity?
When a large enough proportion of a population is vaccinated, which makes it difficult for the pathogen to spread
What does vaccinated people provide?
Measure of protection for those not immune
When is vaccinations most successful?
When they are carried out at the same time
Why do vaccinations sometimes not work?
Already infected Immuno defect Pathogen mutated so antigens not recognised Some pathogens "hide" inside of cells Each pathogen has many varieties
Describe an immune response
Phagocytes engulf pathogen
Activate T-cells which bind to comp antigens on phagocyte
Activates B-cells, which divide into plasma cells
Plasma cells make more antibodies complementary to antigen
