THE ADAPTIVE IMMUNE SYSTEM Flashcards
How does the adaptive immune system’s response differ the most from the innate immune system’s response to infection?
The adaptive immune system targets specific antigens and produces a highly specified response
What is an antigen?
A foreign molecule that binds to T cell receptors or antibodies
Why are memory cells essential to the host’s immunity - in general?
Memory cells help the host remember an antigen if the pathogen were to reinfect
How do some pathogens bypass memory cells in the adaptive immune system?
They change their antigens with each infection, preventing memory cells from recognizing the pathogen with every reinfection.
What is the main reason activated macrophages have to regulated?
Oxidative bursts triggered by activated macrophages are extremely harmful to surrounding tissue in the host. If macrophages are not regulated it can do serious damage.
What structure do antibodies have? Explain the two main parts of an antibody:
Antibodies are Y-shaped molecules that contain a single Fc or constant region and 2 identical Fab or variable regions
What are two functions of the Fc region on an antibody?
The constant region allows antibodies to bind to C1 proteins and bind to Fc receptors on macrophages.
- C1proteins activate the complement system on the surface of bacteria
- Fc receptors trigger opsonization and alert macrophages
What is an epitope?
An epitope is a portion of an antigen that can be targeted by an antibody
How is antibody-antigen specificity exemplified by epitopes?
Antigens can have multiple of the same epitope which can be targeted by a single antibody
What is an advantage of an antibody being able to target several epitopes?
If an antigen has several peptide repeats (epitopes) it gives the antibody multiple areas to bind
What is a good indication that an antibody is working?
The activation of more B cells indicates that the antibody is targeting the right epitopes and effectively killing the pathogen
What are the 4 main types of antibodies? Provide one identifiable factor for each.
- IgG is the most widely released antibody in the body.
- IgM is the first antibody to be released and can perform bacterial agglutination
- sIgA are antibodies that can be secreted outside the body in the form of fluids
- IgE are antibodies associated with parasitic infection and allergies
What part of the antibody differs between the 4 antibody types?
The Fc region
What is affinity?
The strength by which an antigen binds to the Fab portion of an antibody
What is avidity?
Affinity coupled with valence - how many binding sites are available for the antigen and how strong the antigen binds to the antibody.