Flashcards in Immunology Deck (39):
1
What is a non specific response
A response which is immediate and the same for all pathogens
2
What are some examples of non specific response
Physical barriers (skin)
Chemical barriers (HCl in stomach)
Phagocytosis
3
What is an antigen
Any protein or glycoprotein on the cell surface membrane which stimulate an immune response
4
What are two types of phagocyte
Macrophages and neutrophils
They are non specific in their response to pathogens- engulf and digest all foreign cells and viruses
5
What is a specific response
A response which is slower and specific to each pathogen
6
What are some examples of a specific response
Cell mediated response (T lymphocytes)
Humoral response ( B lymphocytes) which produce antibodies
7
What does the immune system identify
-pathogens
- non self material from individuals of the same species (organ transplant)
-toxins
- abnormal body cells (cancer cells or cell infected with viral particles)
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Where are B lymphocytes produced
Produced in the bone marrow
Mature in the bone marrow and then concentrate in the lymph nodes and spleen
9
Where are T lymphocytes produced
Produced in the bone marrow
Mature in the thymus
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What are the 3 types of T lymphocyte
Helper T cells (Th cells)
Memory T cells
Cytotoxic T cell (Tc)
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What do T helper cells do
-attract and stimulate phagocytes to engulf more pathogens by releasing chemicals called cytokines
- they activate cytotoxic T cells
- they activate B cells to divide which increases antibody production
-develop into memory T cells hitch remain in the blood - allows the immune response to respond quicker to a future infection by the same pathogen
12
What does a cytotoxic T cell do
- destroys the body's own cells infected with viruses or cancer cells
- by complementary binding of antigen and receptor and releases the protein PERFORMIN which punches holes in the cell membrane of the antigen
13
What is a plasma cell
- secrete lots of specific monoclonal antibodies
- survive only a few days but produce about 2000 antibodies a second
- responsible for the primary response
14
What is a memory cell
-circulate in the blood for years
- don't produce antibodies
- if they encounter the same antigen they divide and produce more plasma cells
- secondary immune response
15
What does an antibody consist of
Antigen binding sites
Heavy chain of polyproteins
Light chain of polyproteins
Joined by disulphide bridges
( has a constant region and a variable region)
16
What are antibodies features
Made of 4 polypeptide chains
Form antigen- antibody complexes
THEY DON'T HAVE ACTIVE SITES - antigen binding sites
Each binding site is made up of a specific sequence of amino acids folded into a specific 3D shape (tertiary structure)
17
What do antibodies do
They DON'T destroy pathogens directly
They DO bind to specific antigens to form antigen- antibody complexes
They DO prepare them for destruction by phagocytes by agglutination
They DO neutralise viruses
18
What are the advantages of vaccinations
Can eradicate
Fewer people get the disease
Cheaper than healthcare
Less chance of people dying
Become immune without getting the disease
Herd immunity
19
What are the disadvantages of vaccinations
Side effects (eg rashes)
Can get a mild version of the disease
Allergic reactions
20
What does AIDS stand for
acquired immune deficiency syndrome
21
What are the signs and symptoms of AIDS
Dramatic weight loss
Pneumocystis carnill
Gum and mouth infection
Kaposi's sarcoma
22
What does HIV stand for
Human immunodeficiency virus
23
What is special about HIV
It's a retrovirus
24
What is a retrovirus
Means it contains RNA rather than DNA
Viral DNA is made of viral RNA by reverse transcription using the viral enzyme reverse transcriptase
Viral DNA is incorporated into host DNA in the nucleus by viral enzyme integrase
25
What are the consequences of HIV infection
Loss of Th cells
T cells are killed by T killer cells (Cytotoxic T cell)
Reduces the number of T and B lymphocytes meaning there's fewer lymphocytes in the blood, slowing down the immune response
26
What is the acute phase
Lasts 3-12 weeks
Rapid viral multiplication and loss of Th cells
Symptoms: headaches, sweat, sore throat, swollen lymph nodes
Increase in HIV antibodies- now HIV positive
Cytotoxic T cells destroy the infected Th cells
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Chronic phase (asymptomatic or latent phase)
Can last up to 20 years
Viruses continue to reproduce and infect T cells but numbers kept in check immune system
Active virus present so HIV positive individuals are infectious
Multiple rapidly (x10 9 produced each day)
Reduced immune system inefficiency
28
Disease phase
Increase in the number of viruses and ever declining number of T helper cells which weakens the immune system
Opportunistic infections- infections normally controlled in healthy people but potentially life threating
Includes TB, pneumonia and cryptosporidiosis
29
What is active immunity?
Becomes immune by producing its own antibodies after being stimulated by an antigen
30
What is passive immunity?
Become immune by being given antibodies made by a different organism
Natural- when a baby becomes immune due to the antibodies it receives through breast milk
Artificial- when you become immune after being infected with antibodies from someone else
31
What are the differences between active and passive immunity
Active
-requires exposure to an antigen
- takes time for protection to develop
- memory cells are produced
- protection is long term- antibodies are produced which are complementary to the antigen
Passive
- doesn't require exposure to an antigen
- immediate response
-memory cells aren't produced
- protection is short term- antibodies are broken down
32
What are the ethical issues with vaccination
- religious issues
- issues with animal testing
- vaccination on humans can be risky- some side effects sometimes
- if there was an epidemic of a new disease there would be a rush of people who would want the vaccine and there would be difficult decisions on who would receive it first
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What is antigenic variation
Where the pathogens change their antigens
34
What is herd immunity
Where unvaccinated people are protected because of the occurrence of the disease is reduced by the number of people who are vaccinated
35
What is an example of antigenic variation
The influenza virus changes each year meaning people have to be vaccinated each year, especially those who are susceptible to the virus (people aged 65+)
36
What is a polyclonal antibody
Are a collection of many different types of antibody
- with different variable regions
-with different bonding sites which are complementary to different antigens
37
What are monoclonal antibodies
Collection of a single type of antibody that has been isolated and cloned
- produced by fusion of single plasma cells with a tumour cell
38
What are the uses of monoclonal antibodies
1. Targeting medication to specific cell types by attaching a therapeutic drug to an antibody
Direct monoclonal antibody
-specific to antigens on the cancer cells are produced
Indirect monoclonal antibody
- magic bullets
- attaching radioactive drug or cytotoxic drug to the monoclonal antibody
2. Medical diagnosis
Diagnosis of influenza, HIV and many cancers
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