Overview of the Immune System (Part 2) Flashcards
what are 3 words to describe receptors in the innate immune?
- encoded in germline (prescribed)
- limited number
- unchanging
what are 3 types of phagocytic cells?
- macrophages
- neutrophils
- dendritic cells
what is the function of innate response?
local inflammation
how does the innate response change with repeat infection?
it is the same each time
when does the adaptive response develop?
5-6+ days
describe the receptors in the adaptive response
randomly generated and highly diverse + specific
what are the 3 results of adaptive immunity?
- SPECIFIC immune responses
- clear infections
- memory
how does the adaptive response change with repeat infection?
response becomes more rapid and effective with each subsequent exposure
how long does the innate immune response usually last?
up to days
what is the first step of infection?
pathogen breaches the epithelial cell layer and enters the body
how do local innate immune cells recognize the pathogen?
by Pattern Recognition Receptors (PRRs) expressed by the sensor immune cells
what is the role of PRRs?
they are receptors that differentiate btwn self and non-self and recognize PAMPs
what part of the pathogen is recognized by immune cells?
Pathogen-Associated Molecular Pattern (PAMPs)
what are PAMPs?
foreign structures that are common to types of pathogens/microorganisms
what happens once PAMPs on pathogens are detected by PRRs on dendritic cells?
dendritic cells become activated
what happens once PAMPs on pathogens are detected by PRRs on macrophages and neutrophils?
macrophages and neutrophils can induce effector functions on cells, like phagocytosis
how do macrophages and neutrophils amplify the immune response?
produce cytokines and chemokines
what is the role of chemokines and cytokines?
inflammation
what 2 effects do chemokines and cytokines have on blood vessels?
- vasodilation
- vascular permeability
what 3 things do vasodilation and vascular permeability lead to?
- redness
- heat
- swelling
what effect do cytokines and chemokines have on immune cells in the blood?
they recruit them from the bloodstream to the tissue at the site of infection
what does immune cell migration into tissue cause?
pain
what are the 4 hallmarks of inflammation?
- redness
- heat
- swelling
- pain
what is the role of dendritic cells?
present antigen to T cells to activate them
where are immature dendritic cells located?
in peripheral tissue
where do activated dendritic cells migrate when they carry an antigen?
migrate to lymphatic system and lymphoid organs
where does T and B cell activation occur?
lymph node
what is the order of cell activation with dendritic, T, and B cells?
Dendritic cells activates T cells which activates B cells
what type of cells activate T cells (i.e. what type of cells are dendritic cells)?
Antigen Presenting Cells (APCs)
what are the 3 signals that occur to activate T cells?
- activation
- survival
- differentiation
what part of the antigen is presented by APCs?
epitope
what molecule on the APC is used to present the antigen to the T cell?
Major Histocompatibility Complex (MHC)
what does the MHC interact with?
TCR
how is the epitope produced from an antigen?
proteases break down the antigen
what determines the specificity of T and B cells to their antigen?
receptors
where are T cell receptors (TCR) located?
on membrane only
where are B cell receptors (BCR) located?
on membrane or secreted as antibodies
what are antibodies?
secreted immunoglobulin molecules
what are antibodies made by?
made by B lymphocytes and its progeny
what do antibodies bind?
antigens
where are antibodies located?
in serum
are 2 antibodies able to bind the same epitopes on the same antigen?
yes
where do B cells arise and mature?
in bone marrow
where do T cells arise and mature?
arise from bone marrow progenitors and are generated + mature in thymus
what is different about how TCR and BCRs recognize antigens?
TCR only recognize epitopes, BCR can recognize full antigens
describe the specificity of individual B and T cells for an antigen
each cell has individual specificity for 1 antigen –> each cell has many copies of 1 receptor for 1 antigen
is each lymphocyte specific or does it have many types of receptors?
each lymphocyte is very specific and contains many copies of 1 receptor
what does having many types of specific lymphocytes allow for?
allows for a huge diversity of lymphocytes, so the body is ready to respond to any antigen
how is the diversity of lymphocytes accomplished?
by rearranging and editing genomic DNA encoding for the antigen receptors
how are self-reactive cells removed?
if a lymphocyte reacts to a self antigen during development, it is removed
when are lymphocytes selected for activation?
when the lymphocyte interacts with its specific antigen, it is selected and becomes activated
what happens to lymphocytes once they become activated?
lymphocytes proliferate to produce many clones
describe the clones produced from activated lymphocytes?
each clone is reactive against the antigen
why does our body need to make clones of lymphocytes?
bc there is always a lot of pathogen
what type of cells do lymphocytes become once they are activated in lymphoid organs?
effector cells
what are effector cells?
cells that can fight infections
what type of immunity is used by B cells and antibodies?
humoral immunity
what type of immunity is used by T cells?
cell-mediated immunity
what are 3 possible functions of cell-mediated immuntiy?
- some activate B cells
- some help to activate macrophages
- some kill infected cells
in what situation would cell-mediated immunity by T cells need to help activate macrophages?
if the macrophage has taken up a pathogen which prevents phagocytosis
what are the 2 roles of antibodies in humoral immunity?
- clear the antigen
- neutralize the antigen
how do antibodies clear the antigen?
bind the pathogen to recruit phagocytic cells
how do antibodies neutralize the antigen?
bind the antigen so it can’t bind anything else
what happens once the infection has cleared (2)?
- downregulate T cells
- memory
what is immunization?
deliberate induction of an adaptive immune response
what are the 4 types of immunization?
- active - natural
- active - induced
- passive - natural
- passive - natural
what does active immunization require?
requires a working immune system
what does active immunization require?
requires a working immune system
what is natural active immunization?
natural infection
what is induced active immunization?
vaccination
what is passive immunization?
with cells/molecules that mediate immunity
what is natural passive immunization?
mother-to-fetus transfer of antibodies
what is induced passive immunization?
monoclonal antibody therapy
what does the immune system do in passive immuization?
nothing
