BIOL 1260: adaptive immunity Flashcards
5 features of adaptive immunity
specificity, inducible, clonality, unresponsiveness to self, and memory
specificity meaning
each adaptive immune response is targeted against a single molecular shape unique to the infecting pathogen; ex. it will target a unique receptor
inducibile meaning
the system is not on all the time but is activated in response to specific pathogens
clonality meaning
once a T or B cell is induced, they will divide rapidly, creating many clones
unresponsiveness to self meaning
cells of the adaptive immune system do not react to normal healthy cells of the body; autoimmune disorder is a mutation of this
memory meaning
once your body has had a particular pathogen, the adaptive system retains that memory, making it easier to fight the infection if it reoccurs in the future
key cells in adaptive response
the lymphocytes
where do lymphocytes originate?
the red bone marrow of juvenile long bones and adult flat bones
two types of lymphocytes
B and T
B cells origin and maturation location
arise in red bone marrow and mature in red bone marrow
what are other names for B cell adaptive immunity?
humoral response or antibody-mediated response
primary function of B cells
are the primary line of defence in the humor (body fluids like the blood or ISF) by producing and secreting antibodies
T cells two subgroups
helper T cells (TH) or cytotoxic T cells (TC)
T cells origin and maturation location?
origin is red bone marrow and they mature in the thymus
function of T cells
to regulate the adaptive immune response (helper T cells) and attack intracellular pathogens like viruses (cytotoxic T cells)
another name for T cells adaptive immunity response?
cell-mediated immune response
antigen
the pathogen structure that is biochemical shapes that the body recognizes as belonging to a specific foreign invader; antigen in not the pathogen but is the features of the pathogen
epitope
the specific 3D part of the antigen that your body responds to
antigen vs epitope
antigen is the large structure and epitopes are unique structures that are a part of the antigen
3 properties that make an antigen easy to identify
shape, size, and complexity
shape of antigen
the more complex the shape, the easier it is to identify that the antigen is not part of the host body; this is because antigens possess epitopes with a unique 3D geometry
size of antigen
larger molecules are favoured because they are less likely to avoid detection and may have more epitopes
complexity of antigens
the more complex the antigen, the easier it is to identify because it will have more epitopes
examples of antigen features
components of bacterial well wall, pili, capsules, flagella, capsomeres, external structures of fungi and protists like glycoproteins, and allergens like pollen grains, dander (skin flakes), or dust particles
3 types of antigens
exogenous, endogenous, and autoantigens
exogenous antigens
are toxins, secretions, bacterial cell walls, flagella, pili, etc; are the structures found on the outside of the pathogen that can be epitopes
endogenous antigens
result from any pathogen that reproduces inside host cells, causing this to be displayed on the membrane of the cell; often associated with viruses and cancer cells
autoantigens
antigenic molecules that are derived from normal cell processes, so they present on normal, healthy cells in the host body, causing the immune system to not attack
where are B cells found?
the spleen, the blood, and the germinal centres of the lymph nodes
why do B cells have specificity?
due to their B-cell receptors (BCR) that allow them to bind to only one specific epitope
what do BCRs belong to?
a family of proteins called immunoglobulins
immunoglobulins
Y-shaped proteins that help the body fight infection
what binds the BCR together
Disulfide linkages
arrangement of B cell receptors
Y shape that is 4 protein chains; two identical heavy chains and two identical light chains attached to a Fc stem
what is the Y shaped receptor attached to?
an integral membrane protein that helps to anchor the receptor into the cell membrane
what is the antigen binding site?
the arm of a heavy chain and a light chain that are unique to the pathogen; this vary between all the different BCRs
how many BCR types are possible?
billions to even a trillion
how are there so many BCR possibilities?
analogy: you have a closet that has 65 different pairs of pants, 27 different shirts, and 6 different shoes; this can make 10,530 options; multiply this by 2 due to chromosome pairs and combine it with light chain options
what happens when an antigen binds to an antibody?
once binding occurs, a downstream effect will occur, causing many copies to be made of the B cell and also the secretion of antibodies that are identical to the BCR
antibodies vs B cells
antibodies are the B cells but free swimming in the blood and not connected to the cell
what are active B cells called?
plasma cells
another name for antibodies
immunoglobulins
plasma cells
active B cells that have a lot of rough ER for synthesis of proteins that are antibodies
how does your body recognize your own antibodies?
via the Fc stem that is the same for all antibodies
5 tasks of an antibody
neutralisation, opsonization, killing by oxidation, agglutination, and antibody-dependent cellular cytotoxicity
neutralisation
is when a bunch of antibodies bind to an antigen, preventing them to function; more specifically, they are inhibiting the antigen to binding to anything and also make them large and bulky so they are easy to spot
opsonization
this stimulates phagocytosis by stem domains being recognized by the host cells, signaling other cells like macrophages; macrophages bind to the stem domain of the antibody
killing by oxidation
harmful chemicals (O2 and H20 break up into H202 and O3) and harm nearby bacteria; the stem domains can create toxic environments to harm the pathogen
agglutination
as each antibody has two binding sites, this can create a clumping of antigens by each antibody binding to two pathogens; this attracts phagocytes due to large size; large size also means increased chance of filtration outside of the spleen, making it easier to isolate and be recognized by the immune cells
antibody-dependent cellular cytotoxicity (ADCC)
this takes advantage of the Fc stem region through it being attractive to NK cells that bind to this; the BCR will bind to the antigen, and through this chain the NK will release its enzymes
do B or T cells have more unique receptors?
B cells
shape of T cell receptor
not Y shaped like B cells, but are two parallel glycoproteins that link together in the membrane
difference between TCR and BCR
BCRs bind to epitopes and TCRs bind to MHCs
what binds to T receptors?
MHCs
MHCs
major histocompatibility complexes
how does T cell receptor binding occur?
an antigen presenting cell with present an MHC complex with an epitope that will bind with a T cell (helper T cells); for cytotoxic T cells that bind to MHC I complexes and are activated by helper T cells that are doing the same thing
immunological synpase
is a synapse that occurs when an APC binds to a MHC (that has a antigen or epitope on it) that binds to a T cell, thus activating it
2 types of antigen presenting cells
professionals or inadvertent antigen cells
professional APCs
are dendritic cells, B cells, and macrophages, including neutrophils; these are those that do phagocytosis and present they digested materials and their membranes, stimulating the immune system
inadvertent antigen cells
are cells of the body that are infected with an intracellular pathogen and present endogenous antigens on its surface; this is especially common with viruses
how does a phagocytic cell present antigens?
the residual body (aka epitope) will bind to an MHC II protein on the inside on the phagocyte and this fusion will cause an exocytosis that will presenting this on the membrane; so this is an APC with MHC II bound to the epitopes
how do infected cells present antigens?
after infection of a pathogen, the host cell will present epitopes of the pathogen via fusing with MHC I
MHC II vs MHC I
MHC II is associated with professional APCs (phagocytes) and MHC I is associated with inadvertent APCs (those infected with a pathogen)
another name for cytotoxic T cells
CD8 cells
cytotoxic T cells
attack infected or cancerous cells after binding occurs with the MHC to the CD8 receptor; this will trigger the release of cytotoxic chemicals that will kill the infected cell, thus stopping the spread
another name for helper T cells
CD4 cells
helper T cells
will help regulate either cytotoxic T cells or B cells
type I helper T cell
regulates cytotoxic T cells
type II helper T cell
helps regulate B cells
helper T cells job after binding
release cytokines (hormones that are signalling molecules) when bound to MHC presenting epitopes
why is HIV so harmful
because it targets CD4 receptors that are essential for regulating cytotoxic and B cells
where does the APC usually travel to?
lymph nodes or spleen to find cells to activate
what are APCs attractive to?
helper T cells
how are helper T cells activated?
via the immunological synapse between the APC and the helper T cell and the cytokines which are interleukins released from APCs that turn on the cell
what happens once a helper T cell is activated?
it divides like crazy, is stored away for memory, and starts producing and secreting its own interleukins that activate cytotoxic T cells or B cells
two ways plasma cells may be activated
by simply a receptor binding to an antigen or by an indirect route of a B cell phagocytosing a pathogen, presenting an MHC II complex on its surface, binding with a helper T cell, in which the helper T cell will secrete interleukins to activate it to a plasma cell
how are cytotoxic T cells activated?
by endogenous antigens that are attractive to helper T cells and cytotoxic T cells; the cytotoxic T cell will be activated by interleukins secreted by the helper T cells
what is clonal deletion?
eliminating lymphocytes that target our own healthy cells
universal blood donar
O-
universal blood receiver
AB+
type A blood
has A antigens and anti-B antibodies
type B blood
has B antigens and anti-A antibodies
type AB blood
has A and B antigens and neither antibodies
O blood type
has no antigens and has both anti-A and anti-B antibodies
Rh+
has Rh antigens
Rh-
has no Rh antigens
where are blood antigens located?
on the RBC
where are blood antibodies located?
in blood plasma
how are blood types determined?
genetic factors
what are blood antigens called?
agglutinogens
what are blood antibodies called?
agglutinins
Rh antibodies
you are not born with these; they will only develop if a Rh- person receives Rh+ blood
Rh receivement
Rh + can receive from + and -, but - can only receive from -
blood type clumping example for type A-
anti-serum A will clump, anti-serum B will not, and rh will not clump
what is the regulator of the immune system?
helper T cells
autoimmune disease
failure of adaptive cells to undergo apoptosis and target the autoantibodies our healthy cells instead
clonal deletion process for T cells
occurs in the thymus for T cells; it is a pop-quiz that first asks if the cell will respond to MHC I complexes; if yes, it moves on to round 2 testing it it can recognize MHG-autoantigens
clonal deletion process for B cells
occurs in the red bone marrow; no step one, just asking if they can recognize MHC-autoantigens
agglutination
aka clumping
what % of people are Rh+
85%
hemolytic disease of newborns
occurs when a Rh+ fetus is in a Rh- mom and can only cause problems after the first pregnancy; after the first pregnancy with an Rh+ baby, the mom will acquire Rh antibodies that can damage the fetus during development
how is hemolytic disease of newborns prevented?
the mother can receive immunosuppressants
major transfusion reaction
occurs when the antigen of the donor is met with the antibodies of the recipient, causing an adaptive response to be produced and this goes on until all donor antigens are destroyed
example of a transfusion reaction
A donor and O recipient
minor transfusion reaction
occurs when the donor antibodies are attacking the recipient antigens; this does not cause an adaptive response because the antibodies are already provided
active meaning
refers to stimulating the adaptive response along with a memory component
passive meaning
no memory response occurs, only the providing of antibodies
natural active example
getting sick and creating your own antibodies and memory response
natural passive example
is via the mother supplying antibodies by breast milk; this only provides temporary protection and there is no memory component associated with this
artificially active
aka vaccines; an inactive form of a virus or bacteria is provided, stimulating an immune response and a memory response
passive artificial
provides antibodies via antitoxins or gamma globulin serums; ex. snake venom antibodies are provided from someone else
