Module 1 Flashcards
What type of immunity exists before infection
Innate immunity
What type of immunity develops after infection and is tailored to recognize and eliminate a specific threat?
Adaptive immunity
What cells are characteristic of innate immunity
phagocytes, macrophages, neutrophils and nk cells
what cells are characteristic of adaptive immunity
lymphocytes
What are the two types of adaptive immunity
humoral and cell mediated
antibodies recognize and eliminate what type of antigens
extracellullar
humoral immunity is mediated by what
antibodies made by b cells
cell mediated immunity is mediated by what
t lymphocytes
what is the target of cell mediated immunity
intracellular
what is the role of helper t cells
activate macrophages to kill phagocytosed microbes
what is the role of cytotoxic t cells
kill infected cells and eliminate reservoirs of infection
specificity
able to distinguish extremally subtle differences between antigens
able to distinguish extremally subtle differences between antigens
specificity
clonal expansion
increases number of antigen specific lymphocytes
specialization
generates responses that are optimal for defense against different types of microbes
allows immune system to respond to newly encountered antigens
contraction and homeostasis
what are lymphocytes
B and T cells
what do b cells do
recognize extracellular antigens and make antibodies
what do t cells do
recognize intracellular antigens and function to destroy microbes or infected cells
where do b cells mature
bone marrow
what is a BCR and how many do each b cell have
B cell receptor, each b cell expresses one unique antigen binding receptor known as BCRs
what stimulates clonal expansion
binding of antigen to a naive b cells bcr causes the b cell to become activated and divide
antigen activated b cells differentiate into what
effector plasma cells
what do plasma cells do
produce a large amount of secreted antibodies and are short lived
Memory B cells
have long life spans and display membrane bound antibodies
where do t cells mature
thymus
each mature t cell expresses what
one unique tcr
CD4 are what
Helper cells
CD8 are what
cytotoxic cells
t cells require what to be activated
t cells require apcs to present antigens to them to become activated
activated t cells are referred to as what
effector cells
helper t cells orchestrate what
adaptive immune response, cell mediated and humoral
helper t cells acivate what
APCs
helper t cells mediate immune response through the secretion of what
cytokines
upon antigen recognition cytotoxic t cells do what
kill cells that infected with foreign intracellular microbes or cells that are damaged
what is the function of regulatory t cells
inhibit the responses of other immune cells, function and division
what are cytokines
polypeptides produced in response to microbes and other antigens that mediate and regulate immune and inglammatory reactions
autocrine
act on the cell that produced them
paracrine
act on nearby cells
endocrine
large amonut of cytokine produced and can act at a distant site
pleotropism
one cytokine can act on different cell types and mediate diverse biological effects
redundancy
multiple cytokines have the same functional effect
what does IL-4 do
stimulates b cells to produce igE and CD4 t cells to differentiate into TH2
what does IL-2 do
cause b cells to prolifeerate
IFN-y and TNF together do what
increase expression of class I MHC molecules
IFN-y and IL-10 anatognize
IFN-y activates macrophages while IL-10 inhibits the activation of macrophages
IL-10 function
inhibition of macrophage activation
if microbes breach epithelial barriers what do they encounter
macrophages
what do macrophages do
express surface receptors that bind and help ingest microbes and produce toxic molecules and cytokine to destroy microbes as well as recruit other leukocytes to sites of infection
extracellular microbe strategies
secretion of antibodies that bind extracellular microbes to block their entry into cells and promote ingestion and destruction by phagocytes
intracellular microbe strategies
CLTs destroy cells infected by intracellular microbes that are not accessible to antibodies
what do apcs do to help activate lymphocytes
apcs capture microbes and digest microbial proteins into peptides and express them on MHC
Clonal expansion hypothesis
antigens select for and activate pre existing cells expressing receptors specific to the antigen cells then expand from each clone and have identical antigen receptors
activated cd4 t cells proliferate and differentiate into what cells
effector cells
IL-2 does what
is produce early in the immune response and stimulates proliferation
IFN-y does what
activates macrophages to enhance ingestion and killing of microbes
activated cd8 t cells are called what
CTLs
the response of b cells to antigens requires the help of what
helper t cells
antibodies coat micbroes
opsonization
ingestion by phagocytes
phagocytosis
contraction
the expanded clones of lymphocytes that took response die thus restoring homeostasis
monocyte
circulating precursor cell to macrophages
fully differentiated form of b cell that secretes antibodies
plasma cell
phagocytosis and killing of microorganisms activation of t cells and initiation of immune response
macrophage
what cells are phagocytes
macrophages and neutrophils
describe the steps of phagocytosis
phagocytes are recruited to sites of infection where they recognize and are activated by microbes, phagocytes then ingest microbes and destroy them. they also secrete cytokines
in cell mediated immunity what cells activate macrophages to become more effective at killing microbes
antigen stimulated t cells
in humoral immunity what what stimulates phagocytes
antibodies produced by b cells coat or opsonize microbes with antibodies to promote phagocytosis
what is the most abundant circulating cell
neutrophils
what are the first cells to migrate to sites of infection
neutrophils
what are recruited from the blood into sites of infection
inflammatory monocytes
once monocytes enter tissues what happens
they mature into macrophages
where are microglial cells found
macrophages found in the CNS
Kupffers cells
found in the liver
alveolar macrophages
pulmonary airways
osteoclasts
found in bone
mast cells
present in the skin and contain cytoplasmic granules filled with cytokines histamine and express antigen binding surface receptors to trigger the release of cytoplamic granule content
what is the major type of APCs
dendritic cells
what are the types of cells that have apcs
macrophages b cells and dendritic cells
dendritic cell role in innate immunity
capture of antigens
dendritic cell role in adaptive immunity
antigen presentation to activate naive t cells
once dendritic cells are activated what happens
they migrate to lymphoid organs to encounter t cells
langerhans dcs
epidermal layers
classical dcs
majority found in skin mucosa and organs and migrate to lymph nodes
inflammatory dcs
arise from monocytes in inflamed tissue
plasmacytoid derived dcs
come from plasmacytoid cells and are early responders to viral infectiosn
where do macrophages present to t cells
at the site of infection
where do b cells present antigens to t cells
within lymph nodes and spleen
where are follicular dendritic cells found
germinal centers of secondary lymphoid tissues in association with activated b cells
what dont follicular dendritic cells do
do not arise in the bone marrow, do not express antigen presenting molecules, do not function as antigen presenting cells for t cells
what do follicular dendritic cells do
found in lymphoid folliicles, express membrane receptors for trapping antigen antibody complexes, participate in selection of activated b cells
what are lymphocytes
cells of the adaptive immune system that express clonally distributed antigen receptors
Lymphocytes function
recognize and distinguish different antigens
acquired immune deficiency syndromes
individuals that have reduced numbers of lymphocytes in circulation and have impaired protection from infection
where do b cells mature
bone marrow
regulatory t cells
cd4 t cells that develop in the thymus and are designed to dampen the immune response
alpha beta t cells
cd4 and cd8 t cells, major class
gamma delta t cells
smaller population of t cells
nk are similar to what
CTLs
NKT cells
share features with NK and T cells and have alpha beta receptors but lack diversity
gamma delta t cell, B-1, and NKT are apart of what
innate immune system
where do b cells mature
lymph nodes or spleen
naive t cells do what
naive t cells leave the thymus as mature cells and are activated in peripheral lymphoid organs
naive b cells express what ig
IgM and IgD
survival signaling is done by what type of antigens
self antigens, provide weak signals to suuport survival but are weak and do not trigger differentiation
IL-7 and BAFF
survival signaling
important cytokine that mediates the process of homeostatic proliferation
IL-7
lymphoblasts
activated lymphocytes that become large and proliferate extensively
activated lymphocytes express what surface proteins
IL-2, L-selectin, IL-7, adhesion molecules, CCR7
what antibodies do memory b cells express
IgE and IgA
memory t cells express high levels of what receptor
IL-7 receptor CD127
KLF-2
transcription factor required for naive t cells
T-bet, GATA-3 and RORyT
transcription factors required for differentiation of CD4 t helper cells
ILCs
innate lymphoid cells that are similar in function to t cells but lack antigen receptors
