2.4 Immunology Flashcards
What are the 2 types of cells of the immune system?
leukocytes
stem cells
Where do leukocyres come from?
derived from bone marrow stem cells
What are stem cells?
undifferentiated cells that can continually divide
What does totally potent mean?
stem cells can differentiate into any type of cell
What does multi-potent mean?
can differentiate into a certain type of cells
what are the 2 types of stem cells?
embryonic
bone marrow
What are the 2 types of leukocytes?
phagocytes and lymphocyte
What do phagocytes do?
carry out phagocytosis - engulfs the pathogen
How can you identify a neutraphil?
e-shaped nucleus
How would you identify a macrophage?
c-shaped nucleus
How would you identify a lymphocyte?
nucleus takes up most of the cell
Why do phagocytes alone not provide immunity?
do not produce memory cells
What are the two types of phagocytes?
macrophages and neutraphils
What are the 2 types of lymphocytes?
B cells and T cells
What do lymphocytes do?
capable of self and non-self recognition
kills pathogens and remebers them so provides immunity
What type of cells are the non-specific immune response?
phagocytes
What type of cells are involved in the specific immune response?
lymphocytes
What do antigen presenting cells do?
once killed a pathogen, they can take the secretion of the antigen and present it to activate the immune system
What type of cells are antigen presenting cells?
macrophages
B cells and T cells
What antigen is on a B cell?
membrane-bound antibodies
What antigen is on a T cell?
membrane bound protein
What is an infection?
an interaction between the pathogen and the body’s various defence mechanisms
What is immunity?
the ability of organisms to resist infection by protecting against disease-causing microorganisms or toxins
What type of lymphocyte does cell mediated resposes involve?
T lymphocytes
What type of lymphocyte does the humoral resposne involve?
B lymphocytes
What can be identified from its antigens?
pathogens
non-self material
toxins
cancer cells
What is the issue with cell recognition and transplants?
the immune system recognises the transplant as non-self and attempts to destroy it
How do you minimise self cells attacking a transplant?
matching the transplant as close as possible to avoid tissue rejection
What drugs are used to minimise the immune response to a transplant?
immunosuppresant drugs
Why is there a lag time between exposure to pathogen and bodys defences?
clonal selection is occuring
What are the 2 non-specific responses?
physical / chemical barriers
phagocytosis
What are the 2 specific responses?
cell-mediated response
humoral response
What happens to lymphocytes that attach to the bodys own cells?
they either die or are suppressed
What is apoptosis?
programmed cell death
What are the 2 types of WBC?
lymphocytes and phagocytes
What is the process of phagocytosis?
- the phagocyte is attracted to the pathogens by debris or toxins from pathogen
- the phagocyte attaches to the pathogen by receptor binding points
- phaocyte changes shape to engulf pathogen
- lysosomes within phagocyte migrate towards pathogen to form a phagosome
- lysosomes release lysozymes into phagosome
- hydrolysis products are abosrbed by phagocyte
How is the phagocyte attracted to the pathogen?
by chemical products of the pathogen, it moves towards the pathogen down a conc grad
How does the phagocyte attach to the pathogen?
phagocyte has several receptors on its cell-surface membrane that attach to the chemicals on the pathogen’s surface
How do the lysosymes break down the pathogen in the phagosome?
they hydrolyse the cell walls of the bacteria forming soluble products
What is an antigen?
any part of an organism or substance that is recognised as non-self by the immune system and stimulates an immune response
Where is the B lymphocytes produced?
bone marrow
Where are the T cells produced?
thymus gland
How can T cells find invader cells?
phagocyte presents pathogen antigen
body cells presenting viral antigen
transplanted cells have different antigens
cancer cells antigens
What are antigen-presenting cells?
cells that display foreign antigens on their surface
What are the only antigens a T cell responds to?
antigens that are presented on a body cell
What is the process of cellular response?
- pathogens invade body cells/ taken in by phagocytes
- antigens are displayed on cell-surface of phagocyte
- receptors of a specific Th cells fits onto the antigens
- attachment activates the T cell to divide rapidly by mitosis - forms clones
- one clone will divide to form memory cells
- the other clone will secrete cytokenes to stimulate b cells
What do the cloned T cells do?
develop memory cells
stimulate phagocytes
stimulate B cells to divide and secrete antibodies
activates cytotoxic T cells (Tc cells)
What are Th cells?
T helper cells
What do T helper cells do?
their receptors bind to the antigens
What are Tc cells?
cytotoxic T cells
What do cytotoxic T cells do?
kills abnormal cells and body cells that are infected by pathogens
How do cytotoxic T cells kill cells?
produces a protein called perforin that makes holes in the cell-surface membrane
What do B cells do?
produces a specific antibody that responds to one specific antigen
How does the antigen enter the B cell?
by endocytosis
What is clonal selection?
The process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
What are the 2 types of cells that the B cell clones develop into?
plasma cells
memory cells
What do plasma cells do?
secrete antibodies into the blood plasma
How long do plasma cells survive?
a few days
What are the plasma cells responsible for?
the immediate defence of the body against infection
What is the primary immune response/
the initial production of antibodies and memory cells
Where do memory cells circulate?
in the blood and tissue fluid
What do memory cells do?
responsible in the secondary response - detect same antigen and divide rapidly into plasma cells and more memory cells
By what cell divison proces do B cells clone themselves?
mitosis
Describe the process of the humoural response?
- the surface antigens on pathogen are taken up by B cell - specific antibody receptors complementary to antigen
- B cell processes and presents antigen on surface
- Helper t cells - attach to antigen and activate B cell
- b cell divides by mitosis to give a clone of plasma cells others divide into memory cells
- the cloned plasma cells secrete antibodies that specifically combine with antigen
- some B cells develop into memory cells
What is an antibody?
a protein with a specific binding site synthesised by B cells
How does an antibody react with the antigens?
binds to them
How many polypeptide chains does an antibody have?
4
What are the long polypep chains in an antibody called?
heavy chains
What are the short polypep chains in an antibody called?
light chains
How does the antibody bind to the antigen?
by the antigen binding sites - complementary in shape to antigen
What is formed when an antibody binds to an antigen?
an antigen-antibody complex
What two regions are on a antibody?
variable region
constant region
What are the two ways an antibody prepares a bacteria cell for destruction?
causes agglutination of the bacterial cells
serve as markers
What is agglutination?
clumping together cells
Why does agglutination of cells make destruction of them easier?
easier for the phagocytes to locate them as they are less spread out in the body
How do antibodies serve as markers?
present the antigen on the surface and they stimulate phagocytes to engulf the cells which they are attached to
What is a monoclonal antibody?
a single type of antibody that can be isolated and cloned
What are the uses of monoclonal antibodies?
targeting medication to specific cell types
medical diagnosis
pregnancy tests/ lateral flow tests
vaccines
How are monoclonal antibodies used to treat cancer?
monoclonal antibodies are produced that are specific to antigen on cancer cells
antibodies are given to patient and attach themselves to the receptors on the cancer cells
attach to the surface of the cancer cells and block the chemical signals that stimulate their uncrontrollable growth
What is the advantage of using monoclonal antibodies to treat conditions?
they are not toxic
highly specific
lead to fewer side effects than other forms of therapy eg. chemo
What is indirect monoclonal antibody therapy?
attaching a radioactive or cytotoxic drug to monoclonal antibodies so killing the cells the antibody attaches to
What are cytotoxic drugs?
a drug that kills cells
What are magic bullets?
antibodies with drugs attached
What is the advantage of using magic bullets?
can be used in smaller doses so cheaper and less side effects
What are monoclonal antibodies used to diagnose?
influenza
chlamydia
certain cancers
What hormone is found in the mothers urine while pregnant?
hCG
How do pregnancy tests work?
- antibody are linked to coloured particles
- if hCG is present it will bind to these antibodies
- the hCG-antibody-colour complex will move alone the strip until it is trapped by an immobilised mAb creating the coloured line
- behind this row of immobolised mAbs is another row which bind to any mAbs which don’t have hCG attached - this is the control line
What is an issue with monoclonal antibodies?
they use mice to produce anitbodies and tumour cells - cancer must be induced
What is passive immunity?
where an individual receives antibodies from an external source. The antibodies are not made by the individual., theres no direct contact with the pathogen
What is an example of passive immunity?
immunity is acquired by a fetus when antibodies pass across the placenta from the mother
What is active immunity?
produced by stimulating the production of antibodies by the induvidual’s own immun system, direct contact with the pathogen
What is natural active immunity?
results from an induvidual becoming infected under normal circumstances
What is artificial active immunity?
forms the basis of vaccination - inducing an immune response in an induvidual
What is vaccination?
the introduction of the appropriate disease antigens into the body either by injection or by mouth
What does a vaccine contain?
one or more types of antigen from the pathogen
What are vaccines used for (not treating disease)?
used as a precautionary measure to prevent induviduals contracting a disease
What factors does a successful vaccination programme depend on?
economic availability
side-effects
producing and storing must be available
means of administration
possibility of herd immunity
Why mustn’t a vaccine have bad side effects?
may discourage induviduals from being vaccinated
What does administrating the vaccine require?
staff training with appropriate skills
What is herd immunity?
when a sufficiently large proportion of the population has been vaccinated, making it difficult for a pathogen to spread within a population
Who might not be vaccinated?
babies
immunodeficient people
what might happen if someone who is immunodeficient is vaccinated?
the vaccine will fail to induce immunity
Why might a vaccine not eliminate a disease?
infection immediately after vaccination
mutation of pathogen
pathogens can hide
induviduals with ethical issues against vaccines
Why does infection immediately after vaccination reduce the vaccine affect?
their immunity levels are not high enough for the disease to be prevented so the vaccine is ineffective
What is antigenic variability?
the antigen on the surface of the pathogen change suddenly
What are some ethical reasons someone wont be vaccinated?
MMR
religion
medical reasons
What are the ethical issues of vaccines?
testing on animals
side-effects can be unknown - possible long-term harm
should they be compulsory for full success
religions
What does HIV stand for?
human immunodeficiency virus
What does HIV do?
causes AIDS
What does AIDS stand for?
acquired immune deficiency syndrome
What enzyme is present in HIV?
reverse transcriptase
What does reverse transcriptase in HIV do?
catalyses the production of DNA from RNA
What is a retrovirus?
a group of viruses that have the ability to make DNA from RNA
What is the process of replication of HIV?
- HIV enters the bloodstream and circulates around the body
- protein on HIV readily binds to protein CD4 - most likely on T helper cells
3.capsid fuses with cell-surface membrane, the RNA and enzymes of HIV enter the Th - Reverse transcipt’s role
- newly made DNA is moved into T help cell nucleus and inserted into T cells DNA
- HIV DNA in nucleus creates mRNA using cell’s enzymes
- mRNA leaves nucleus via nuclear pore and uses cell’s protein synthesis mechanism to form new HIV particles
- HIV particles break away from cells membrane forming the lipid envelope
What does mRNA do in HIV replication?
contains the instructions for making new viral proteins and the RNA to go into the new HIV
How does HIV cause AIDS?
by killing or interfering with the normal functioning of T helper cells so cannot stimulate B cells to produce antibodies or cytotoxic T cells
What is likely to cause death with AIDS?
secondary diseases because of inadequete immune response
eg - lung infections
What does the ELISA test do?
uses proteins to detect the presence of a protein in a sample but also the quantity of the protein
How do antibiotics work on bacterial cells?
weakens the cell walls made of murein which makes the walls unable to withstand the pressure of water entering the cell
so the cell burts and the bacterium dies
Why dont antibiotics work on viruses?
there are no metabollic mechanisms or cell structures that the antibiotic will interupt
protein coat instead of murein so there are no sites where the antibiotic could work
visues within a host cell cannot be reached by antibiotics
What is the process of maturation of T cells?
- in bone marrow, immature T cells divide by mitosis
- in the thyymus, each T cell matures and the T receptors are produced
- mature T cells ciculate, same as Th and some as Tc - each have a different T cell receptor
What is the structure of a T cell receptor?
it is a protein so:
tertiary structure with h bonds, disulphide bridges and ionic bonds betweenR groups
What is the maturation of B cells?
- in bone marrow, immature B cells divide by mitosis
- still in bone marrow, each B cell matures - production of antibody receptors
- Mature B cells circulate and concentrate in the liver and spleen, each B cell has a different antibody receptor
What type of protein are antibody receptors?
globular protein
What is the 1st line of defence?
barriers
What are examples of Barriers?
stomach acid
mucus
skin
tears, saliva and sweat
What does skin contain?
collagen and keratin
What does stomach acid do in immunity?
denatures and breaks down proteins in pathogen
What do tears, sweat and saliva all contain?
lysosymes - digest bacterial cell walls
What is the 2nd line of defence?
non-specific immune system
What are examples of non-specific immune system?
phagocytosis
blood clotting
fever
inflammation
What does inflammation do in immunity?
secretes chemicals that increase blood flow for more white blood cells circulating
What does blood clotting do in immunity?
prevents the entry of pathogens
What does a fever do in immunity?
trys to denature the enzymes and proteins or inhibit enzymes
What is the 3rd line of defence?
specific immune system
What are the 2 types of specfic immune response?
cellular response and humoral response
What happens after antigen presentation?
clonal selection and expansion
What is resistance?
the tolerance to withstand chemicals
What are examples of antigen presenting cells?
viral capsid
transplanted organs
toxins
bacterial antigens
macrophages
infected body cell
cancerous cell
What is clonal selection?
he process of matching the antigens on an antigen presenting cells with the antigen receptors on B and T lymphocytes.
What is clonal expansion?
The production of many genetically identical daughter cells through cell division of the activated B or T lymphocyte after clonal selection.
What do T helper cells do in the cellular response?
bind to antigen on antigen presenting cell (clonal selection)
divide by mitosis (clonal expansion)
secretes cytokenes to stimulate B cells
some others divide to form memory cells
What do cytokenes do?
stimulate B cells to divide and form plasma cells and memory cells
What do cytotoxic T cells do in the cellular response?
complementray cytotoxic T cells binds to antigen on antigen presenting cell and activated by a T helper cell
divides by mitosis
releases Perforin proteins - inserted into infected cell’s membrane creating a pore - water enters by osmosis = cell lysis
What is the role of the memory T cells in the cellular response?
remain in the blood for decades
can identify the same antigen more quickly at next exposure
Describe the humoural response in the secondary immune response?
the antigen enters the body for second time
memory cells that were produced in primary response, respond and divide to form more plasma cells
plasma cells secrete antibodies
What is the role of B cells in the humoral response?
complementary B cells binds to presented antigen (clonal selection)
clonal expansion
differentiates into plasma B cells and some memory cells
What is the role of plasma B cells in the humoral response?
produces antibodies
What organelles are in a plasma B cell and their role?
packed with RER - synthesis of antibodies
golgi - packages and secretes antibodies
mitochondria - produces ATP for synthesis and exocytosis
What is the role of memory b cells in the humoral response?
remain in the blood for decases secreting small numbers of antibodies
they multiply in response to secondary exposure to antigen and give a faster and stronger response
Why is there a lag time for the primary response?
clonal selection and clonal expansion taking place
Describe the secondary resposne in terms of the graph
it has a much faster antibody secretion
there is a higher max conc of antibodies that lasts longer
What are the 2 circumstances that there will be no secondary response to a pathogen?
1.highly viralent pathogen that is fatal at 1st exposure (if the antigen has attached to the cells quicker than the lag time before the 1st response)
- antigenic variability on the same pathogen - mutation of antigen
What type of protein structure is an antibody?
quaternery - globular
What bond joins the polypeptide chains together in an antibody?
disulphide bridges
Which region of the antibody has a different primary structure?
the variable region
What is the other name for an antibody?
immunoglobulins
What are all the actions of an antibody?
cause bacterial lysis
prevent pathogen/ toxins entering host cells
coats pathogen to aid phagocytosis
deactivates flagella to aid phagocytosis
causes pathogen to agglutinate
What is the method of forming monoclonal antibodies?
- inject small mammel with antigen to stimulate humoural response
- isolate the plasma B cells that secrete the antibodies needed for this antigen
- fuse plasma cell with myeloma cell to form a hybridoma
- isolate hybridoma that produces the correct antibody
- clone the specific hybridoma to produce many monoclonal antibodies
What is direct monoclonal antibody (mAb) therapy?
mAbs are specific to patient’s cancer cells
it blocks the chemical signalling for uncontrolled mitosis by binding to the receptor of the patient’s cancer cell
What is indirect mAb therapy?
mAb has cytotoxic drug attached - magic bullet
attaches to cancer cell antigens
causes apoptosis of cancer cell
What are the advantages of using mAb as a treatment for cancer?
mAb are non-toxic
mAb are specific
can use a lower dosage - fewer side effects and cheaper
What is an example that mAbs can diagnose?
PSA - prostate specific antigen = a protein in the blood which can be an warning sign of prostate cancer if high levels are found
What does the ELISA test stand for?
Enzyme Linked ImmunoSorbent Assay
How does the direct Elisa test work?
- well in test plate to attache mAb specific to antigen being tested
- wash test plate - to remove unnattached mAbs
- add patient’s blood sample, if antigen present they will bind to mAb
- wash - to removed unbinded antigens
- add 2nd mAb specific to antigen, that has an enzyme attached
- wash - remove unattached 2nd mAb
7.add a colourless subrate that the enzyme will break down to a coloured product - a visible colour change occurs - shows the conc of antigen
What is the sequence of the indirect ELISA?
antigen
1st mAb
2nd mAb
enzyme and substrate
What are the ethical issues of mAbs?
small mammels are used to produce mAbs and Myloma cells - need to induce cancer to do so
requires informed consent from patients to be used
failed drug trials
What is natural immunity?
obtain immunity through life processes
What is artificial immunity?
immunity from deliberate exposure
What is active immunity?
lymphocytes activated and antibodies are produced
What is passive immunity?
lymphocytes are not activated and no antibodies are produced
What is an eg of natural active immunity?
infection by pathogen
What is an eg of active artificial immuntiy?
antigen injection
What is an eg of natural passive immunity?
breastfeeding and across the placenta
What is an eg of artifical passive immunity?
antibody injection
Why would an antibody injection be used instead of an antigen injection?
if a faster a response is needed to a highly virralent pathogen
common for armed forces and medical staff for travelling to different countaries
What could be in a vaccine?
dead/ inactive pathogen
attenuated (weakened) pathogen
antibodies
antigens
live pathogen
toxoids
What is needed for a vaccination to be successful?
antigen should be highly immunogenic = triggers a strong immune response and produces a high conc of antibodies
there should only be one antigenic type of pathogen
why is using a live pathogen in a vaccine more effective?
there is a continual exposure to antigen
Why is using dead pathogens less effective in vaccines?
limited exposure to antigens
Why are booster vaccines used?
to produce the secondary response
they are required when memory cells are short lived
What is herd immunity?
occurs when a large proportion of a population are vaccinated against a disease which prevents the spread of the disease to unvaccinated individuals
What is ring immunity?
f a person is exposed to a virus, a vaccine for that virus is given to others who are in close contact with that person, such as close family and friends.
Who linked the MMR vaccine with autism?
Andrew wakefeild
What is the simplified sequence of HIV replication?
- binding
- fusion
- reverse transcriptase
- intergration
- activation
- assembly
- budding
What is a retrovirus?
a virus that has RNA and reverse transcriptase
Why does the T helper cell shrink after HIV replication?
HIV takes away the cell membrane for its own membrane
How can children be born with HIV?
the antibodies and virus can cross through the placenta
