Chapter 17 part II: specific defenses of the host Flashcards
what is the difference between an antigen and an epitope?
Antigens are glycoproteins located on surface of organism.
Epitopes are numerous small regions located antigens that are the binding sites for antibodies
How many different epitopes does a single B or T cell recognize?
only one per single B or T cell
when is antigen specificity set?
Randomly during lymphocyte development and remains constant for the life of the lymphocyte
What is a naïve lymphocyte?
fully functional lymphocyte that has not been activated
What is an activated B cell called? What does an activated B cell do?
Plasma (effector) cell - produce the antibodies that recognized the specific pathogen’s antigen that caused activation
What are the major delays before the adaptive immune system is fully active?
Epitope match
clonal expansion
what takes place during the epitope match delay?
Epitope match – time it takes for one of the millions and millions of naïve lymphocytes to become activated by matching with correct epitope of pathogen
what takes place during the clonal expansion delay?
Clonal expansion – process of creating new daughter cells of effector cells and memory cells for specific pathogen (around 1000 copies)
how long does the epitope match delay take?
18-36 hours
how long does the clonal expansion delay take?
18-36 hours
What does a T cell use for its specific receptor?
T cell receptor
what does a B cell use for its specific receptor?
surface-bound antibodies
How many different B cell and T cell specificities can be generated?
10^15 different B cell specificities
10^18 different T cell specificities
How is a naïve B cell activated? What does the B cell do with the antigen after the antigen binds to sIg (surface-bound immunoglobulin)?
When a B cell binds its antibodies to the epitope of an antigen, it then digests the pathogen and presents its antigen using MHC II. CD4+ 2 (TH2 cells) then bind to this antigen and secrete cytokines that activate B cells.
What is the CD designation for T-independent B cells? What type of antigens are targeted by this new subpopulation of B cells?
CD5+ intraperitoneal B cells
repeating polysaccharide antigens (do not require cytokines of CD4+ TH2 cells)
what are repeating polysaccharide antigens?
parasites (helminths)
What is the full name of the protein (hint: what complex) that allows for T cell activation? (not just the abbreviation)
MHC = major histocompatibility complex
What MHC type do Antigen presenting cells use to display an antigen?
MHC II
what are antigen presenting cells?
dendritic cells
macrophages
B cells
How are CD 8+ T cells activated? What happens to the cell that activates a CD 8+ T cell?
Are activated by antigen being presented by MHC I
Programmed cell death occurs
How are CD 4+ T cells activated?
Antigen presenting cells present antigen using MHC II to CD4+ TH cells
What is immunological memory?
A second exposure to the same antigen results in a more effective immune response (rapid rise in antibody titer following a second response to antigen)
What are some of the mechanisms that contribute to the development of memory?
Encountering a pathogen will produce active immunity for the pathogen and passive immunity which creates memory cells. Can also occur by encountering pieces of pathogen within vaccines and passive immunity would be created as well through that.
You should know the basic structure of an individual antibody molecule.
Y shape protein composed of 4 polypeptide chains
Top of antibody contains variable regions
Bottom stem is constant region
