Ch 17 pt 2 Specific Defenses of the Host Flashcards
What is the difference between an antigen and an epitope?
Antigen - are molecules capable of stimulating an immune response located on the surface of organism
Epitope - numerous small regions located antigens that are the binding sites for antibodies
what is an epitope?
numerous small regions located antigens that are the binding sites for antibodies
what is an antigen?
molecules capable of stimulating an immune response located on the surface of organism
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?
Plasma (effector) cell
What does an activated B cell do?
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 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?
B cells bind to an antigen using Slg (surface bound antibody)
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
What does the B cell do with the antigen after the
antigen binds to sIg (surface-bound immunoglobulin)?
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?
CD5+ intraperitoneal B cells
What type of antigens are targeted by this new subpopulation of 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
How are CD 8+ T cells activated?
Are activated by antigen being presented by MHC I
What happens to the cell that activates a CD 8+ T
cell?
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?
the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered before
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.
- Secreted from plasma cells
- Y-shaped protein
- Composed of 4 polypeptide chains
- The bottom stem is called the constant
region
What are the five different classes of antibody?
IgD
IgA
IgE
IgG
IgM
IgG (monomer) – blood plasma
IgA (dimer) – body secretions
IgM (pentamer) – blood plasma (produced by effector B cells)
IgE (monomer) – mast cells surface
IgD (monomer) – B cells surface
Which antibody crosses the placenta?
IgG
Which antibody class is secreted in breast milk?
IgA
Which antibody classes are normally used in rapid antibody tests?
IgM
What antibody class normally indicates you had an infection in the past?
IgG
Which antibody class normally indicates you presently have that infection?
IgM
What are the mechanisms of antibody protection?
- Opsonization
- Agglutination/Precipitation
- Neutralization
- Complement activation
- Antibody–dependent cellular cytotoxicity: ADCC
Does an antibody kill by itself?
No
What is the name for the protein that allows for T cell activation?
Major Histocompatibility Complex 1
how does antibodies help with opsonization?
antibodies bind to foreign object to increase phagocytosis
how do antibodies help with agglutination/precipitation?
use their variable binding sites to clump multiple antigens together. Large masses ease phagocytosis
how to antibodies help with neutralization?
physically blocks toxin or pathogen from binding to human cell
how do antibodies help with complement activation?
IgG and IgM activates classical pathway of complement to cause lysis with membrane attack complex
Name and breifly describe the major delays before the adaptive immune system fully activates
- Epitope Match: specific receptor on a lymphocyte must bind to the correct epitope
- Clonal Expansion: Each newly activated lymphocyte will rapidly reproduce daughter cells (effector and memory cells)
Name and briefly describe 3 (out of 5) mechanisms of antibody protection
- Osponization: antibody attached to foreign objects is easier to phagocytize
- Agglutination/Precipitation: Antibodies use their two identical binding sites to bind to multiple antigens.
3.Neutralization: Antibody physically blocks toxin or pathogens from attaching to human cell
- Complement activation: Antibodies bind complement, results in the MAC (cytolysis)
- Antibody dependent cellular cytotoxicity: ADCC, Utilizes immune cells to attack labeled targets without using phagocytosis
