Adaptive Immunity Flashcards
what are the 3 major function of adaptive immunity?
- recognize nonself/foreign
- respond to nonself
- remember nonself
what are the 2 aspects of the respond to nonself response of adaptive immunity?
- effector response
2. anamnestic response
describe the effector response of the respond to nonself function of adaptive immunity?
eliminates or renders foreign material harmless
describe the anamnestic response of the respondto nonself function of adaptive immunity
upon second encounter with the same pathogen, the immune system mounts a faster andmore intense response
where do the B and T cells of the adaptive immune system initially arise?
both in bone marrow
where do B cells mature?
Bone marrow
where to T cells mature?
move from bone marrow to Thymus
what do B and T cells go through during maturation and why?
extensive screening to avoid self-reactivity
what are the 4 characterisitcs of specific/adaptive immunity?
- discrimination between self and nonself
- diversity
- specificity
- memory
describe the discrimination aspect of specific/adaptive immunity?
usually responds selectively to non-self, producing specific responses against the stimulus
describe the diversity aspect of specific/adaptive immunity
generates enormous diversity of molecules against all types of pathogens in contact with
describe the specificity aspect of specific/adaptive immunity
can be directed against one specific pathogen or foreign substance among trillions
describe the memory aspect of specific/adaptive immunity
response to a second exposure to a pathogen is so fast that there is no noticeable pathogenesis
what are the 2 types of specific immunity based on mediation?
- humoral immunity
2. cellular immunity
what is humoral specific immunity also called? what is it based on?
antibody-mediated immunity, based on antibody activity
what is cellular specific immunity also called? what is it based on?
cell-mediated immunity, based on action of specific kinds of T lymphocytes (T mobile is a CELLULAR company)
what are antigens?
self and nonself substances that elicit an immune response and react with the products of that response
describe antigens as molecules
large and complex
what are antigenic determinant sites? what are they also called?
epitopes; are sites on antigen that reacts with specific antibody or T cell receptor
what are the 4 types of specific immunity based on how they are acquired?
- naturally acquired active immunity
- artificially acquired active immunity
- naturally acquired passive immunity
- artificially acquired passive immunity
describe naturally acquired active immunity
type of specific immunity a host develops after exposure to a foreign substance
describe artifically acquired active immunity
intentional exposure to a foreign material (ex. vaccine)
describe naturally acquired passive immunity
transfer of antibodies, e.g., from mother to fetus across placenta, or mother to infant in colostrum or breast milk
describe artificially acquired passive immunity
pre-formed antibodies or lymphocytes produced by one host are introduced into another host
what is essential for proper functioning of the immune system?
recognition of foreigness; distinguishing between self and nonself
what does recognition of foreigness allow for?
selective destruction of invading pathogens without destruction of host tissues
what does recognition of foreigness involve?
major histocompatability complex
what is the major histocompatability complex?
MHC; collection of genes that encodes for self/nonself recognition potential of vertebrates
how many classes of MHC molecules are there?
3
where are class I MHCs found?
in almost all types of nucleated cells
what are Class I MHCs important for?
organ transplants, self/nonself
where are Class II MHCs found?
only on antigen presenting cells
what are Class II MHCs required for?
required for T cell communication to macrophages, dendritic cells, and B cells
what do Class III MHCs include?
secreted protein not required for self/nonself recognition
what do Class I and Class II MHCs bind to?
antigens in cells
what are the 2 types of MHC binding to antigens?
- endogenous
2. exogenous
describe endogenous MHC binding to antigens, and which class does this
Class I binds to antigen peptides that originate in the cytoplasm and present the antigen to CD8+ T cells
describe exogeneous MHC binding to antigens and what class does this
Class II binds to antigen fragments that come from outside the cell and present to CD4+ T helper cells
what are T cells?
major players in cell-mediated immune response
what do T cells play a major role in?
B cell activation
describe T cells (2)
- immunologically specific
2. function in a variety of regulatory and effector ways
how long are mature T cells naive until?
until activated by antigen presentation
once activated, what do T cells do?
proliferate into effector cells and memory cells
what do effector T cells do?
carry out specific function to protect host
what are the 3 kinds of effector T cells?
- T helper cells
- cytotoxic T lymphocytes
- regulatory T cells
what are T helper cells also known as?
CD4+ T cells
what are T helper, or CD4+ T cells activated by?
antigen presentation with Class II MHC
when do Class I MHCs really kick in?
endogenous, when the antigen is already inside/has changed the nucleated cell
what do Class I MHCs do when an antigen has already fucked up a cell?
grab it, migrate to outside of cell and present it
what does a Class I MHC displaying an antigen outside do?
causes cytotoxic T cells to come in
what 3 things do cytotoxic T cells do once they are recruited by a Class I MHC?
- make more cytotoxic T cells because there’s probs more antigens to get
- make memory T cells for next time
- the new cytotoxic T cells do apoptosis of fucked up cells
when do Class II MHCs come into play?
when an antigen-expressing cell (dendritic, macrophage, or B cell) encounters an antigen
what do Class II MHCs do?
once their associated antigen-expressing cell has englufed and broken up a pathogen, they express it on outside of cell to recruit T HELPER cells
what 3 things do T helper cells do once recruited by Class II MHCs?
- activate B cells
- recruit neutrophils to the area
- make more T helper cells bc there’s probs more antigens
what are the 2 ways that B cells can be activated?
- by T cells (T dependent)
2. by epitopes on antigens (T independent)
when a B cell is activated by a T cell, what binds where and what is the result?
T helper cell binds to class II MHCs on outside of cell, activates more pathways
where do epitopes bind when they activate B cells?
to antibodies on the B cells
when a B cell is activated, what are the 3 pathways that occur?
- make more B cells
- make B memory cells
- make plasma B cells
what do plasma B cells do?
make more antibodies, that play a role in opsonization
what must happen to B cells to continue mitosis?
must be activated by a certain pathogen, replicate and differentiate into plasma cells that secrete antibodies
describe B cell activation (3)
- typically antigen specific
- leads to proliferation and differentiation into plasma cells
- two mechanisms (T dependent and T independent)
what are BCRs?
B cell receptors, associate with other proteins, specific immunoglobulin receptors for a specific antigen
which T cell activation mehcanism is more effective and why?
T cell independent is more effective, because those antigens have a lot of epitopes, easy to respond to.
why is T cell dependent activation less effective that T cell independent? (2)
- antibodies produced have a low affinity for antigen
2. no memory B cells formed
define antibodies (3)
- immunoglobulins (Ig)
- glycoprotein made by B plasma cells (activated guys)
- serves as antigen receptors (BCRs) on B cell surfaces
where are antibodies found? (3)
- blood serum
- tissue fluids
- mucosal surfaces of vertebrates
what do antibodies do?
recognize, bind, and neutralize the antigen that caused its production
describe the function of immunoglobulins (2)
- bind antigens specifically: mark for attack, activate nonspecific defense mechanisms to destroy
- mediate binding to host tissue, varius immune cells
what is the first component of the complement system?
immunoglobulins
what are the 5 classes of immunoglobulins?
- IgG
- IgD
- IgM
- IgA
- IgE
describe IgGs (2)
- 80% of serum immunoglobulins (most prevalent)
2. do opsonization, neutralization, activates complement system
describe IgDs
signal B cells to start antibody production
describe IgMs (2)
- first Ig in all immune responses
2. agglutination, activates complement
describe IgAs/secretory IgAs (2)
- secreted across mucosal surfaces
2. found in tears, saliva, breast milk, mucosal-associated lymph tissue
describe IgEs (2)
- lowest serum level
2. elevated in parasitic infections and allergic reactions
when does the primary antibody response occur?
there is a several week lag or latent period after inital exposure to antigen before occurs where no antibody is detectable in blood
describe the order of Igs in the primary antibody response
IgM first, then IgG
what produces the antibodies seen in the primary immune response? what else do they produce?
plasma B cells, they also make memory B cells
why is the secondary antibody response quicker?
due to the memory B cells produced in the first response
describe the action of antibodies (2)
- bind antigens with great specificity
2. antibodies coat foreign invading material (opsonization)