Immunology Flashcards
(19 cards)
4 types of cells that can stimulate an immune response
Pathogens
Abnormal body cells eg cancer cells
Foreign cells eg transplants
Toxins
Describe phagocytosis
( stimulated by a chemical)
1. Pathogen is engulfed by endocytosis by the phagocyte
2. Enters the cytoplasm in a vesicle and forms a phogosome
3. Lysozyme which contain hydrolytic enzymes fuse with the phagosome and digests the pathogen into waste material
4. Waste material exists by exocytosis
5. Antigen presents itself on the surface of the cell membrane forming an Antigen presenting cell to alert other white blood cells of the pathogen
Antigen definition
A molecule usually a protein that stimulates an immune response and results in production of specific antibiodes. On the surface of a cell membrane of a cell
Response of t lymphocytes
A specific t helper cell with a specific reception protien binds to complementary APC and is activated. It rapidly differentiates by mitosis by clonal selection into t memory cells which remain in the blood for a rapid and extensive secondary response.
More T helper cells which bind to APC and release cytokines which stimulates a specifically complementary b cell, activate t cytokine cells, attract phagocytosis to area of infection and form t memory cells
T cytokine cells locate and destroy infected body cells. They bind to the APC and release performing which makes holes in the cell surface membrane
Activation of b cells
They are stimulated by cytokines and differentiate by mitosis by clonal selection to produce memory B cells which remain in the blood for a rapid and extensive secondary response and plasma B cells which secrete vast quantities of spefic antibodies complementary to the antigen
Antibody definition
Antibodies are produced in response to a foreign antigen- has binding sites complementary to antigen .Produced by specific plasma b cell
Structure of antibody
Y shaped
Quaternary structure made from 4 polypeptide chains= 2 light and 2 heavy
Variable constant which is the same in all antibody
Variable region which has a different tertiary structure in different antibody.
How do antibodies assist in the destruction of pathogens
Agglutiantion = bind to specific antibodies and clump them together
Optimisation = mark pathogens so phagocytes recognise and destroy more easily
Lysis = bind and lead go destruction of the pathogens membrane
Memory cells
They remain in the blood for a rapid and extensive secondary response
If pathogen encountered again then cytokines relased by tc cells which stimulate then to divide by clonal selection by mitosis into plasma b cells and more memory b cells. Plasma b cells produce antibodies in a short period of time
What is antigenic variability?
Mutation in the variable region of an antibody which means change in primary structure which lead to change in tertiary structure so no longer complmentary to pathogen and will have to initiate a immune response from the beginning. This makes it hard to produce vaccines.
What are the 3 types of immunity
Active and passive
Active vs passive immunity
Exposure to antigen vs no exposure to antigen
Takes a long time to develop vs fast acting
Long term vs short term
Antibodies are produced vs no antibodies
Memory cells are produced vs no memory cells
What is an vaccination
It’s when a weakened, attenuated or dead version of the pathogen is injected to intitaite an immune response and produce specific antibiodies complementary to the antigen
Vaccination ethics
Animal testing
Human testing
Cost
Availability
Side effects
What are monoclonal antibodies?
They are produced from one clone of plasma b cells and used in immuno assays, research, targeting drugs etc
Elisa test
Add patients blood sample to well bound with monoclonal antigens
Antibodies in blood bind to antigens in well
Wash any unbound Antibodies
Add second antibody with enzyme attached which binds to antibody and wash out any unbound
Add solution containing substrate which forms coloured compounds. The more intense the colour is the more antibody therefore the longer the person has been infected
HIV structure
Attachment protiens
Lipd envelope
RNA
Reverse transcriptase
Capsid
HIV replication
Attachment protiens on HIV bind to receptor protiens on t helper cell
Capsid fuses with cells surface membrane and releases RNA and reverse transcriptase.
Reverse transcriptase coverts RNA into cDNA which is inserted into hosts nucleus and the person in now infected
Transcription produces MRNA and translation produces HIV protiens. Formation of virions which bud of host cell membrane and form lipid envelope
AIDS AO2
Less t helper cells means less activation of b cells which means less plasma b cells so less antibodies produced and less able to destroy pathogen
