Immune System Flashcards
(43 cards)
How do cytotoxic T-cells work?
Attach to the foreign antigens on an infected cell. They then secrete perforin into the cell, a protein that makes holes in the cell-surface membrane and leads to cell death
What are the 4 types of T-cell?
- helper T-cells
- cytotoxic T-cells
- memory T-cells
- regulatory T-cells
What are the roles and features of plasma B-cells?
- only last a few days
- responsible for primary immune response
- secrete antibodies into plasma (around 200/sec)
What is the second line of defence against pathogens?
Non-specific inflammatory response, involving phagocytes and lysosomes
What is agglutination?
The process of a network of antibodies and particles clumping together due to the fact that antibodies have two sites where they can bind.
What is a macrophage?
A type of antigen presenting cell most commonly found in inflammatory sites
What is an example of indirect monoclonal antibody therapy?
T-DM1 is being trialled in the treatment of breast cancer. Involves trastuzumab, emtansine and a third component ensuring the drug remains inactive until it binds
What are the four ways that vaccines are made (fairly) harmless?
- Killing the pathogen while leaving antigens unaffected
- Using bacterial toxins that are milder, rather than using the pathogen itself
- Weakening the pathogen while leaving antigens unaffected
- Using genetically engineered cells to produce a microbial protein
What are the two types of active immunity?
Natural - from exposure to the disease
Artificial - from vaccination
What is the third line of defence against pathogens?
Specific immune response involving lymphocytes
What is the structure of an antibody?
Y-shaped molecule with two long and two short polypeptide chains. Disulphide bridges hold the polypeptide chains together. Variable regions on the top of each ‘Y’ point, that bind with each specific antigen
What are the two ways to obtain passive immunity?
- Through a mother’s breastmilk
- Directly given short-term antibodies e.g. anti-venom
What are the key features of a neutrophil?
- can move into other tissues by squeezing through capillary wall gaps
- cytoplasm that is full of lysosomes
- cell surface membrane covered in protein receptors
What four roles do helper T-cells play?
- stimulate division of B-cells in clonal selection
- activate cytotoxic T-cells
- increase rate of phagocytosis
- develop into memory cells
How does HIV cause symptoms of AIDS?
The take over of the T-helper cells results in them all dying. This means that there is no immune response, allowing opportunistic diseases to infect the person and all pathogens make the person feel unwell, causing the flu-like symptoms
What is active immunity?
When the body responds to an antigen by producing specific antibodies and memory cells, and direct exposure is required
What is passive immunity?
When the body is given antibodies with no exposure to the pathogen
What role do surface proteins play in the immune response?
Allow the body recognise cells as ‘self’ or ‘non self’, so the antibodies know which cells to attack
Why may vaccines not work or be suitable?
- impaired immune system so no response is produced
- contracting the disease before vaccination has developed
- antigen variability
How can agglutination assist in destroying pathogens?
- neutralise the pathogen by preventing them from being able to divide and develop
- attract phagocytes by acting as a ‘marker’, making them more visible to phagocytes
How does a prostate specific antigen test work?
1) Antibodies specific to PSA are bound to the surface of the test
2) Blood sample is added and any antigens present will bind to the antibodies
3) Secondary antibody with enzyme attached added that only binds to primary antibody is antigen is present
4) Complementary substrate added, which the enzyme reacts with to form a coloured product
What are the stages of phagocytosis?
1) Chemotaxis - chemicals released by pathogens cause phagocytes to move towards
2) Adhesion - receptors on surface of phagocytes attach to the chemicals on pathogen surfaces
3) Ingestion - phagocytes ingest the pathogen and form a membrane-bound vesicle (aka phagosome)
4) Digestion - lysosomes fuse with the phagosome and release the lysozymes, which hydrolyse the pathogen
What is an example of direct monoclonal antibody therapy?
Trastuzumab in the treatment of breast cancer
What is an antigen-presenting cell?
An immune cell that recognises pathogens, then engulfs them through phagocytosis and presents the pathogen’s antigens on the surface of their own cell, activating the T-cells
