Immune Response Flashcards
Define antibody
Protein produced by white blood cells that help break down a pathogen
Define immune
When you are no longer able to catch a disease
Define vaccination
The insertion of a dead or weakened pathogen in order to cause an immune response
Describe the basics of an antigen
.On the surface of all cells are chemical markers called antigens.Your body recognises the antigens on your cells as your own.Anything with different antigens to yours stimulates an immune response.In an immune response, your body will recognise the antigen as foreign and will attack it
Which molecules can act as anitgens?
. Proteins. Glycoproteins
Why are antigens important?
. Initiate immune response to pathogens. Allowing recognition of faulty cancer cells. Recognition of cells from other organisms of the same species
How does antigenic variation work?
.Some pathogens can mutate which causes changes in the surface antigens.The memory cells from the first infection won’t recognise the different antigens.The immune system must carry out a primary response against the new antigens
What is phagocytosis?
Phagocytosis is when phagocytes (a type of white blood cell) engulf and break down an invading pathogen in order to protect the body, it is a part of the immune system.
What type of response is phagocytosis?
Phagocytosis is a non-specific response
Describe the steps of phagocytosis
- The phagocyte is attracted to the pathogen by detecting the toxins it is releasing2. The phagocyte moved towards one of the pathogens3. The phagocyte begins to surround the microbe. A vacuole forms around it.4. The phagocyte engulfs the pathogen5. The pathogen is inside a vacuole like phagosome in the phagocyte6. Lysosomes fuse with the phagosome and secrete digestive enzymes into the phagosome7. The pathogen inside the phagosome is digested by these enzymes and destroyed
What are the roles of T cells?
.Produces memory T Cells.Stimulates phagocytosis.Kills infected cells – making holes in their membranes.Stimulates B cells to divide
How does an antigen presenting cell come about?
B cells with an antibody that is complementary to the antigen of invading pathogens takes up the surface antigenThis antigen is presented on the surface of the B cell
What happens to an antigen presenting cell?
A T helper cell attaches to the processed antigens on the B cells thereby activating the B cell meaning it produces by mitosis to produce clones
When B cells divide by mitosis what is formed?
They can either become memory cells or plasma cells
Where are memory cells found and what are ready to do?
Memory cells circulate in blood and tissue fluid in readiness to respond to a future infection by the same pathogen whos antigen was used in the process of forming them
What do plasma cells do?
Plasma cells produce antibodies that exactly fit the antigens on the pathogens surface
What do antibodies do?
The antibodies attach to antigens on the pathogen and destroy them
If the same infection occurs again what do memory B cells do?
If the same infection occurs again the memory B cells divide and develop into plasma cells that produce antibodies
List 3 functions of antibodies
.Coat the pathogen with antibodies to make it easier for the phagocyte to engulf it.Coat the pathogen with antibodies to prevent it from entering host cells.Antibodies bind to and neutralise (inactivate) toxins produced by the pathogen
How are B cells and C cells both needed to remove a pathogen from the body?
The responses interact with each other.T cells activate B cells and antibodies coat pathogens making it easier for phagocytes to engulf them
If you see the word humoral in the exam what do you think?
B cells
What produces antibodies?
B cells, more specifically plasma cells
Are antibodies specific?
yes
Name 6 parts of an antibodies structure
- Antigen binding sites2. Variable region3. Constant region4. Light chains5. Heavy chains6. Receptor binding sites
Draw and label antibodies
idk check your revision guide or google if its right?
Why are the variable regions on antibodies called that?
As the binding sites differ
What gives the variable region its specific 3d shape in antibodies?
The sequence of amino acids
In antibodies, where does the constant region bind to?
receptors
Each binding site on an antibodie is c____________ to a specific antigen
complementary
When an antibodies binding site binds to an antigen what is formed?
forms an antigen-antibody complex
Roles of antibodies
.Antibodies do not directly destroy antigens.Agglutination.Markers
What happens in agglutination
Antibodies clump bacteria cells together which is helpful as it means they can be taken in by phagocytes for digestion much more easily since they are easier to locate as they are less spread out
How do antibodies act as markers?
They can act as markers that stimulate phagocytosis
How do pregnancy tests work?
A hormone called HCG is found in the urine of women only when they are pregnant, pregnancy tests can detect these hormones..Monoclonal antibodies that attach to HCG can be mass produced and stuck down to a test strip on a pregnancy test, while on a separate part of the pregnancy test antibodies attached to blue heads can be placed..If your pregnant and wee on it, the HCG in your urine will attach to the antibodies on the blue heads and the urine will carry them down to the test strip where they will attach to the stuck down antibodies and change the colour of the strip – showing a positive result..If you are not pregnant and wee on it, the urine still carries the blue beads and antibodies down the test to the test strip but they won’t attach to the stuck down antibodies, and so a colour change does not occur – a negative result.
How do monoclonal antibodies help diagnose PSA?
.men with prostate cancer tend to have high levels of the protein PSA (prostate specific antigen) in their blood due to the fact they produce so much of it. Through the use of a monoclonal antibody that can interact with it, it is possible to get a measure of the level of PSA in a sample of blood.
Name 3 ethical implications of monoclonal antibodies?
.Use of mice.Death of patients with MS.Drug trials are dangerous
How is the use of mice in the production of monoclonal antibodies an ethical issue? Has any help been put in place?
.Production of monoclonal antibodies includes the use of mice.The formation of tumour cells includes the deliberate inducing of cancer in mice.Guidelines have been drawn up to reduce suffering but many people still believe it is unethical
How is the death of people with MS in treatment with monoclonal antibodies an ethical issue? Has any help been put in place?
.Monoclonal antibodies have saved many lives through diagnosis and treatment.But they have also led to the deaths of some people with multiple sclerosis.Informed consent is needed, where people know all the details of treatment including possible death before they consent to it
How are drug trials with monoclonal antibodies an ethical issue? Has any help been put in place?
.March 2006, 6 healthy volunteers underwent a test for a new monoclonal antibody in London.They all suffered from organ failures, as a result of T cells overproducing chemicals that stimulate an immune response or attack body tissues.All 6 survived, but it still raises questions about the ethics of drug trials
What is immunity?
The ability of an organism to resist immunity
What are the two types of immunity?
.Passive.Active
What is passive immunity, with examples
.Antibodies introduced from an outside source.Abs are not produced by the individual so they are broken down.No memory cells.Short livedFor example – .Anti-venom.Immunity acquired by a foetus from the mother
What is active immunity
.Production of abs is stimulated by the individual.Direct contact with the pathogen/antigen.Takes time to develop.Long lasting
What two forms does active immunity come in?
.Natural – met the disease yourself, normal immune response.Artificial – from a vaccine, induced immune response, few symptoms
Define huminisation
making the monoclonal antibodies suitable for human use (since they come from mouse tissue)
Uses of monoclonal antibodies
.Separating chemicals from mixtures.Immunoassay (detecting concentrations of macromolecules in solutions).Cancer treatment.Transplant surgery
What can antibodies be used to identify?
Antibodies can be used to identify flu, hepatitis, chlamydia and types of cancer
What is a non-specific response?
immediate and same for all pathogens
What are the two nonspecific responses?
.Physical Barrier (skin).Phagocytosis
What is a specific response?
slower and pathogen specific
What are the two specific responses?
.Cell – mediated response (T-Lymphocytes).Humoral response (B-Lymphocytes)
Where do T cells mature?
.T Lymphocytes mature in the thymus gland
What do T cells respond to?
own cells altered by viruses/cancers (foreign material inside body cells) or transplanted tissues
How can different cells display antigens on their surface?
- Phagocytes that have engulfed and hydrolysed a pathogen present some of the pathogens antigens on their surface2. Body cells invaded by a virus present viral antigens on their surface as a distress signal3. Cancer cells are different from normal cells and present antigens on their surface4. Transplanted cells from the same species have different antigens on their cell surface
What are cells that display foreign antigens known as?
antigen-presenting cells
How do T cells become activated?
The phagocyte places antigens from the pathogen on its own cell-surface membraneReceptors on certain helper T-cells fit exactly onto these antigensThis activates other T cells to divide rapidly by mitosis and form a clone
What do cloned T-cells do?
.Develop into memory cells that allow a fast future response to the same pathogen .Stimulate phagocytes to engulf pathogens via phagocytosis .Stimulate B-cells to divide and secrete their antibody .Activate cytotoxic T cells
What do cytotoxic T cells do?
.Cytotoxic T cells kill abnormal body cells
How do cytotoxic T cells kill abnormal body cells?
.They produce a protein called perforin that makes holes in the cell surface membrane.This makes the cell freely permeable, killing it
What are cytotoxic T cells effective against?
.This action is very effective against viruses as they replicate inside cells
Define pathogen
Disease causing microbe
Define phagocyte
WBCs that travel in the blood and tissues, destroying pathogens
Define phagocytosis
Mechanism where phagocytes engulf pathogens and hydrolyses them using enzymes
Define immune
Resistant to a particular infection or toxin owing to the presence of specific antibodies
Define antigen
Molecule that triggers an immune response
Define antibody
A protein made by lymphocytes in response to the presence of an antigen
Define t lymphocyte
Type of WBC produced in the bone marrow but matures in the thymus. Coordinates immune response and kills infected cells – cell mediated response
Define helper t cell
Bind to antigens presented by antigen presenting cells. This binding stimulates T cell to divide rapidly.
Define antigen presenting cell
Cells that display foreign antigens on their cell-surface membrane.
Define b lymphocyte
Type of WBC produced by and matures in the bone marrow. Present in bodily humour. Humoral immunity. Produce antibodies.
Define memory cell
Produced by B cells. Live for decades. Provide long-term immunity. When they encounter the same pathogen again they divide rapidly into more plasma and memory cells to immediately fight the infection - secondary immune response
Define plasma cell
Secrete antibodies into blood plasma. Survive for only a few days. Destroy pathogens and toxins. Immediate defence only - primary immune response
Define cytotoxic T cell
Kills infected cells by introducing perforin molecules into their CSM, causing them to take in water and burst.
Define vaccination
Introduction of a vaccine subcutaneously or orally that contains pathogen antigens capable of initiating an immune response.
