1-16 The Immune Response Flashcards
Lag/inductive/latent phase
period of time before antibody can be detected after initial exposure
Logarithmic/exponential phase
period when antibody production begins resulting in an exponential increase in antibody concentration
Steady state phase
peak antibody concentration is reached
decay/decline phase
antibody concentration falls followed by period of time where trace amount of antibody can be detected
what is the secondary response?
after initial exposure to antigen, resulting immune response remains primed to respond to that antigen
secondary response differs from primary response:
shorter lag higher rates of antibody synthesis higher peak of antibody titer longer persistence of antibody predominance of IgG class molecules higher affinity of antibody Requires less antigen to illicit response (more sesnsitive)
Toxin
molecule made by anything living
toxoid
Toxoid - take that toxin, make it non-toxic but still has same sequence/structure so that injection will cause an immune response and antibodies that will target the toxin.
why can’t you become immune to tetanus naturally?
The amount of tetanus toxin needed to form the immune response would kill you. Can’t become immune to tetanus toxin via the toxin itself.
descibe the tetanus vaccine
normally the toxin gets into cells, splits apart, and the active enzyme (A) reaches inhibitory neurons and causes extreme muscle contraction
tetanus + formaldehyde - A-B structure unable to break apart. B can no longer deliver A.
why do small botox injections work?
small enough to work but not small enough to cause “immunity” like a vaccine. this is why you can get multiple botox shots over time.
problem with not immunizing for tetanus?
someone comes into hospital after exposure, giving an immunization then will take 5-7 days to have an effect, too long of a period for the primary response to help them
antibodies initially produced will start out with ___ affinity that will be mosty Ig_
low affinity. will be mostly IgM. At some point, class switch to IgG and also higher affinity
What dictates the secondary response?
IgG. After second exposue, small IgM response will be the same, but IgG will be magnitudes greater
What do b-cells do? How do they work?
they make antibodies of a range of specificities
Clonal expansion
when right antigen comes into contact with a b-cell, the b-cell it begins to divide
how does affinity increase?
There may be several types of B-Cells that recongize different parts of the antigen moecule, some with high and some with low affinity.
Initially with concentration is high, all the different clones are active. As concentration drops due to immune response pulling the antigen into phagocytes, only the most sensitive b-cells will continue to “See” the antigen and continue to divide/make antibodies.
what paths might a b-cell take?
Some turn into plasma cell which can make large amount of antibody. Some stay as small lymphocytes and become memory cells in spleen/lymph nodes so then once secondary immune response occurs, the plasma cells may be gone that were making IgM and IgG for that molecule. Instead of having lots of b-cells that haven’t been selected for in any way. We start with lots of memory cells that make IgG.
primary vs secondary is based primary on what cell type?
memory b-cells
why do we still get a small IgM response after several exposures?
becuase we make so many b-cells every day that there will always be b-cells seeing the antigen for the “first time” and responding as such.
what happens when you remove the thymus neonatally?
B-Cells are fine but there is no immune response or a small IgM.
t-cell must see things for b-cells to do things.
how do T-Cell and B-Cells interact?
through multiple levels of secretion and multiple levels of cell contact. signals being sent both ways.
describe the control against autoimmune responses
t-cells are able to recongize self vs non-self., B-cells cannot do this
Class switch is dependant on? (class switch of what??)
T-Cells
Hapten experiment
make a simple chemicall, will get antibody response.
Link that simple chemical to a native protein in the body (carrier protein), antibodies for that native protein will be created as well as antibody response against the hapten.
Change the carrier protein, will not get a secondary response against the hapten (b-cells and t-cells are seeing different things). T-cells would being seeing it at an initial exposure.
T-Cell indepent antigens are
rare and only cause B-cells to create IgM, will NOT make any memory cells
T-cells and b-cells in regards to hapten molecules…
see different things, and must be on the “same page” to have coordinated primary and secondary response.
What do macrophages and dendritic cells do?
Present antigen to T-Cells
T-Cells require..
antigen presenting cells
descibe how antigen presenting cells work
cells must take up antigen, place segment on MHC portion of surface.
T-cell has t-cell receptor (TCR) on surfance to recognize the antigen+MHC, will not recognize JUST antigen.
presenting cells must express the cell surfance antigen B7 “this might be dangerous”. this B7 binds to the cd28 of t-cells.
T cell requires both the antigen+MHC as well as the chemical signal.
the antigen presenting cells are initially..
Dendritic cells
how does the composition of antigen presenting cells change as the immune response matures?
once b-cells mature and have seen antigen they becoming stimulated to express both MHC and b7 on surface. Some antigen is taken up and portion placed on MHC.
this means that later in the response, b-cells can become antigen presenting cells
implications of b-cells becoming antigen presenting cells?
in secondary response, thousands of b-memory cells have MHC, have b7, and have high affinity for the antigen that can be presented to T-CElls.
Dendritic cells no longer need to do this alone. - big reason why secondary immune response is much faster.
helper t-cells are distinguished by
surface antigen cd4
b-cells and t-cells tend to do what differently?
see antigens differently and tend to reconize different parts of the antigen
t-cell: recognizes protein carrier molecule/ reacts mainly to antigens that are proteins degraded into peptides
b-cells react to the hapten molecule but may also see the carrier
T-cells react with the _________ and in response to….
These t-cells then______
antigen on the surface of the presenting cell and in response to antigen with MHC and stimulatory molecules.
proliferate and produce factors that stimulate b-cells
many of the daughter b-cells will respond to
t-cell derived factors and differentiate into plasma cells. Some daughter cells will not differentiate into plasma cells but will become memory cells
_____ are responsible for the switch from IgM to IgG
other t-cell factors
describe t-independant antigen structure and response
structure - polymeric molecules with large numbers of repeating subunits that can cause cross-linking of the immunoglobulin on the b-cell.
lymphocytes respond to antigen that is
presented with self-MHC (MHC restriction).
a professional antigen presenting cell must be able to
take up and process antigen
have MHC class II antigen on surface
present the antigen with the MHC II antigen
provide a co stim signal
what activates a b-cell? what happens next?
binding of antigen and stimulation by helper t-cell (Th)
B-cell starts cloning self and turn into effector cells or memory cells (Which stick around)
what do effector b-cells do?
starts producing antibodies
what do effector b-cells do? what are the effector b-cells called?
starts producing antibodies, plasma cells.
what are plasma cells?
plasma cells (differentiated B cells) that make antibodies
what do antibodies do?
tags materials for macrophages and also neutralizes them
what is a common feature of all t-cells?
all have t cells receptors
in addition,
- some have CD4 proteins on surface
- some have CD8
what cells have CD4 proteins? What do they do?
located on helper t-cells (Th), bind to MHCII complexes
attracted to antigen presenting cells that have MHCII complexes
what cells have cd8 proteins? what do they do?
cytotoxic t-cells (Tc), bind to MHCI + antigen complexes
MHC1 marks the infected cell for death (cancer, viruses, etc.)
what happens when a t-cell is activated?
differentiate into effector or memory cells
helper t = in effector mode activates b-cells, releases cytokines (alarm signals)
cyctotoxic t = in effector mode kills cells
what are leukocytes?
white blood cells
Leukocyte Types?
white blood cell types - neutrophils, basophils, eosinophils, lymphocytes (NK, B, T), monocytes, macrophages
two main types of leukocytes
Granulocytes - contains enzyme granules that damage/digest pathogens or release inflammatory mediators into blood (neutrophils, basophils, eosinophils, mast cells) = ones with pH names (neutraol, basic, acidic)
mononuclear leukocytes - involved in both innate/adaptive immune system function (lymphocytes NK B T, monocytes, macrophages)
types of lymphocytes
T-cells (bone marrow then mature in thymus), B-Cells (from bursa, in bone marrow), Natural killer Cells
humoral response vs cell mediated
humoral response - immune response regarding pathogens still floating in the blood (humor)
cell-mediated response - once cells are infected with pathogen
MHC stands for
major histocompatibility complexes
macrophages/dendritic cells after consuming a molecule present on MHC2. (nonspecific)
with b-cells, one specific tpye of membrane bound antibody is formed
when a b cell becomes activated
it will begin to duplicate itself. those duplicates can either become memory cells or plasma cells. the plasma cells will start spitting out non-membrane bound antibodies to either tag the viruses/bacteria or surround them/neutralize.
B-cell may also take in the particle which bound on the end of its antibody, break it up, and attatch it to MHCII to present the antigen
MHCII in specific and non-specific immune response. What recognizes them?
non-specific. phagocyte will consume particle, chew up and place some on its MHCII complex.
specific - whatever binds to the membrane bound antibody will be taken in, and partially displayed on the MHCII complex
Both are recognized by helper t-cells
B-cells do what?
monoclonal B-cells do what?
B-Cells – Express surface immunoglobulin. Each set of monoclonal B-cells is limited to one kind of variable region (idiotype), so the total population of B-cells makes up the repertoire of antibody specificities.
idiotype?
one type of variable region
