IM 4 Flashcards
how is clonal expansion started?
cytotoxic T cell activation with binding of antigen presentation
what is needed for maximal activation of cytotoxic T cell
helper T cells (IL-2 and other cytokines) to stimulate full cytotoxic T cell clonal expansion
what is formed from full cytotoxic T cell clonal expansion?
effector and memory cells
what do activated effector cytotoxic T cells do?
circulate and recognize virus infected cells
what happens with recognition effector cells?
release perforin and granzymes
what happens when perforin is released?
create channel for intracellular entry (similar to MAC)
what happens when granzymes are released?
digestive enzymes enter via perforin created channel
how is perforin and granzymes related?
perforin creates channels and granzymes enter the channels
what is the result of cytotoxic T cells?
-virus infected cells undergo apoptosis
-lots of cells can be lost depending on how many are infected
-virus released into extracellular where other defenses can attack easier
what is the role of regulatory T cells?
suppress immune responses to keep from over-reacting (this provides some balance to immune responses)
what are some possibilities of the mechanism for regulatory T cell?
- Not as many copies made
* Cytokines drive production from helper T cells
* Cytokines that increase clonal expansion, we also have cytokines that decrease clonal expansion
* Negative feedback to IL-2
* Costimulation activation of
*basically countering what we’ve done in past slides
how is B cell activation done?
variable end antigen binding to antigen (clonal selection) and starting clonal expansion
what does maximal activation for B cells require?
helper T cells contributions (IL-2 and other cytokines) to stimulate full B cell clonal expansion
=some effector and memory cells formed
some effector B cells differentiate into…
plasma cells that form antibodies for specific antigen
what are antibody mediated attacks?
specific formed antibodies being released out into circulation
what’s the difference between B cell proliferation and differentiation?
proliferation: B cells make more B cells
differentiation: B cells making plasma cells then antibodies
what’s a direct attack for antibody?
results directly from antigen-antibody binding
what happens with direct attacks antibody?
neutralization, agglutination, precipitation
what is neutralization?
antibody binding antigen blocks antigen attaching to healthy cells or interfering with pathogen chemical reactions
what is agglutination?
clumping when antibody binds to antigen
(Clumping makes antigen + antibody bigger so phagocytosis can detect it easier)
what is precipitation?
soluble antibody and soluble antigen form insoluble product (insoluble more visible to phagocytosis)
what are indirect attacks for antibody?
results from more than just antigen-antibody binding
how is enhanced phagocytosis and antibody dependent cellular cytotoxicity (ADCC) related?
they have very similar processes
- antibody binds to antigen and acts like opsonin
- phagocyte or NK cells with correct receptor attaches to stem end of antibody
- forms bridge between pathogen and phagocyte or NK cell
-enhanced phagocytosis: to make phagocytosis easier
-ADCC: in response to binding NK cell releases cytotoxic chemicals to destroy pathogen
what is the primary response for immunity?
following first contact to antigen
-slow (several weeks) response
-small numbers of specific antibodies
-limited time in blood
what is the secondary response for immunity?
subsequent encounter by same antigen
-quicker response
-larger numbers of specific antibodies
-longer time in blood
what are secondary responses driven by?
stored memory cells
what do secondary responses give?
greatly enhanced immunity toward subsequent infection
what are the 2 types of immunity and their subtypes?
active and passive
-subtypes are natural and artificial
what is active immunity?
exposure to antigen
what is active natural immunity?
exposure to antigen by chance (ex. out in nature and you come across like touching door handle)
what is active artificial immunity
deliberate exposure to antigen (ex. vaccine)
what is a vaccine?
small quantities of living or dead pathogens, toxins, or harmless antigen fragment from pathogen or it’s toxin
what is passive immunity?
direct transfer of already formed antibodies
what is passive natural immunity?
antibody transfer mother to infant
what happens between mother and fetus/
passive natural immunity when lgG moves across placenta
what happens in breast-fed child?
passive natural immunity when lgA in breast milk can move across intestinal lining (this is important early protections as antibody synthesizing is relatively poor in young)
what is passive artificial?
antibody transfer from person to person (injection)
-only occurs in dangerous or fatal conditions where there is no time to wait for active immunity
what’s the catch with preformed antibodies?
they offer immediate protection but have a limited lifespan (weeks or months)
