Antigens and Antigen Presentation Flashcards
most microbial antigens are ….
protein molecules
what are microbes that replicate outside of the host cell
extracellular pathogens
True or False:
most bacteria and parasites are extracellular
true
which pathogens exist outside a host cell prior to infecting it but need to be inside a cell to replicate
intracellular pathogens
what is an example of an intracellular pathogen
virus
when are microbial antigens made
during microbial replication
what type of antigen is made by the pathogen outside of any host cell
exogenous antigen
Is this exogenous or endogenous antigen:
the extracellular pathogen is engulfed by a phagocytic cell and killed inside the cell. The pathogen now presents the antigen.
exogenous antigen - the microbe did not replicate inside
what type of antigen is made by the intracellular pathogen inside a host cell
endogenous antigen
where do most bacteria live and replicate
outside of the cell
True or False:
capsules of some bacteria are usually poorly immunogenic
true
what does it mean to be ‘poorly immunogenic’
an antibody may not be able to bind to the microbe because it is ‘keeping it hidden’
what is the best type of viral vaccine to use
a live, non-encapsulated, attenuated vaccine
what type of bacteria can readily replicate inside macrophages
facultative intracellular bacteria
which is more difficult/ dangerous to deal with - exogenous antigen or endogenous antigen
endogenous antigen
if a cell with endogenous antigen is killed and then re-engulfed. what type of antigen will be presented in the new phagocyte
exogenous antigen - the antigen was made before being in the cell. It was not replicated in the final cell that pick up the antigen
what are very small, obligate intracellular organisms
virus
where do viral contents go once in the cell to replicate
cytosol
what type of antigen is normally created with viruse
endogenous viral antigen
what cells can kill virally infected host cells
natural killer cells
cytotoxic lymphocytes
True or False:
Antibody if present can target extracellular virus
true - important to remember for rabies and the importance of vaccination
what are molecules expressed on the surface of normal cells that in another animal could stimulate an immune response
non-microbial antigens
what is another name for non-microbial antigens
cell surface antigens
what are examples of cell surface antigens
blood group antigens
MHC molecules
CD molecules
what are the nonmicrobial antigens of the blood group antigens
glycoproteins of glycolipids
what are the nonmicrobial antigens of the MHC molecules
protein molecules expressed on the surface of all nucleated cells
what are the non-microbial antigens in the MHC important for
tissue recognition
transplantation medicine
what are CD molecules (cluster of differentiation)
surface molecules on immune cells used to define subsets of lymphocytes
how are CD molecules identified
using monoclonal antibodies
what are the main CD cells we are concerned with
CD 4
CD8
CD25
where are CD4 cells found
T-cells with helper function
where are CD8 cells found
T-cells that kill abnormal cells
where is the CD25 molecule expressed
number of different cells
what is the function of CD25
bind to IL-2
if there is an extracellular pathogen, which cells are used as APCs
dendritic cells
macrophages
B-cells
where do the professional APCs present an extracellular antigen to
MHC-II molecules
what cells are activated after the presentation of an extracellular pathogen to the MHC-II molecules
T-helper cells
what do T-helper cells do
activate B-cells to produce antibodies and macrophages and CTLs to kill target
what is the end result of an extracellular pathogen being presented to the MHC-II
antibody production through humoral immunity
what APCs are responsible for presenting intracellular pathogens
none. intracellular virus has to be presented through MHC-I
how do host infected cells/ tumor cells present their intracellular antigens
MHC-I
what cells are responsible for recognizing the MHC-I antigen signals from the host cells/ tumor cells
CTLs (cytotoxic T-cells)
what is the result of tumor cells/ infected host cells using MHC-I to activate the CTLs
activated CTLs and cell-mediated immunity
(ability to kill infected cells and tumor cells)
what is the function of APCs
process and present exogenous antigens
where do APCs present their exogenous antigens to specifically
CD4+ T-helper cells
what are the non-professional APCs
host infected cells and host tumor cells
when can T-helper cells see antigen
only if it is presented on the surface of an APC within the MHC-II molecules
what type of cell can present endogenous antigen to MHC-1 molecules
any nucleated cell because they all contain MHC-I complexes
what does a B-cell need help from in order to start antibody production
T-helper cells
how do B-cells know what antigen to make
based on what antigen is presented to them through the T-helper cell
