abbas chapter 1 Flashcards
innate immunity
always present blocks entry of microbes includes: - epithelial barriers - phagocytes (esp. NK cells) - complement
takes 6-12 hours
doesn’t react against noninfectious foriegn sugstances
adaptive immunity
B-lymphocytes create antibodies
T-lymphocytes become effector T cells
acts 1-5 days post infection
recognizes antigens but only recognized if the antigens are delivered to lymphatics
types of adaptive immunity
humoral and cell-mediated
humoral immunity
for extracellular microbes
antibodies produced by B lymphocytes
B lymphocytes recognize extracellular antigens
cell-mediated immunity
for intracellular microbes
t-lymphocytes activate phagocytes and kill host cells
t lymphocytes recognize antigens produced by intracellular microbes
humoral immune response (microbe type, responding lymphocytes, effector mechanism, functions)
- extracellular microbe
- B lymphocytes respond
- secrete antibody
- block infections and eliminate extracellular microbes
cell-mediated response (microbe type, responding lymphocytes, functions)
if phagocytised microbe:
- microbe in macrophages
- helper T lymphocytes respond
- activate macrophages to kill phagocytosed microbes
if intracellular microbes:
- intracellular microbes replicate within the infected cells
- cytolytic T lymphocytes respond
- kills infected cells and eliminates reservoirs of infection
clonal selection hypothesis
mature lymphocytes with receptors for many antigens develop before the encounter with those antiges - when antigen presents, that clone cell proliferates
primary immune response
response to first exposure to antigen
mediated by naive lymphocytes
secondary immune response
due to subsequent encounters with same antigen that created a primary immune response
faster and larger response due to activation of memory lymphocytes
phases of response (list)
recognition
activation of lymphocytes
- clonal expansion
effector phase
recognition phase
first phase of immune response
naive antigen-specific lymphocytes locate and recognize the antigens of microbes
activation phase
second phase of immune response
requires binding of antigen to antigen receptors of lymphocytes (signal 1) and other signals from microbes and innate immune system (signal 2)
includes clonal expansion step
some lymphocytes also differentiate into effector cells - secrete antibody (b) or kill infected cells (t)
clonal expansion
occurs during activation phase of immune response
rapid cell division of lymphocytes that encounter antigens
effector cells
generated during clonal expansion step of immune response
some B cells secrete antibody and some T cells kill infected cells
include lymphocytes and other leukocytes - B and T leukocyte lineages, and also granulocytes and macrophages
effector phase
third phase of immune response
effector cells and their products eliminate
only become effector cells when naive lymphocytes get both 1st and 2nd signals
what happens to cells from the immune response after the infection is eliminated?
most cells that were activated die via apoptosis
memory lymphocytes remain and migrate through lymph - some go to site of infection
lymphocytes
the only cells with specific receptors for antigen
key mediators of adaptive immunity
B - mediate humoral response - produce antibodies
T - mediate cell-mediated immunity - only recognize antigens bound to mHC on APCs
NK cells - innate immunity
CD4+ cells and CD8+ cells
CD4+ cells
mature in bone marrow
helper T cells because help B to produce antibodies and help phagocytes to destroy ingested microbes
reduce cytokines
when become effector cells, produce cytokines that activate B cells and macrophages
CD8+ cells
cytolytic or cytotoxic = CTLs
kill cells harboring intracellular microbes
mature in thymus
B cells
mediate humoral immunity
produce antibodies
b-cells become effector cells - become plasma cells - secrete antibody
antigen presenting cells
in epi
capture antiges and transport them to peripheral lymphatic tissue
includes dendritic cells, macrophages
dendritic cells
professional APCs
capture protein antigens of microbes tht enter through epithelia and transport antigens to lymph nodes where portions of antigen recognized by T lymph
macrophages
in epithelium, phagocytose microbes that invade
display these protein antigens to T cells
professional APCs
also present secondary signals to help activate T cell proliferation and differentiation
generative tissues of immune system
primary
T and B lymphocytes mature and become competent to respond here
peripheral tissues of immune system
secondary
where adaptive immune responses to microbes instigated
lymph nodes, spleen, mucosal and cutaneous immune systems
concentrate antigens, APCs and lymphocytes
T and B separated into different anatomical compartments - kept there by cytokines expressed in those areas
lymph nodes
peripheral/secondary tissue
substances absorbed from epithelia and tissues
APCs in nodes sample antigens in lymph as it passes through nodes and dendritic cells go here
antigens become concentrated in draining lymph nodes
B cells are in follicles in the cortex (FDCS there too), while T outside follicles (as are dendritic cells)
follicles have germinal center when activated
spleen
blood equivalent to the lymph node
dendritic cells and macrophages trap and concentrate blood borne antigens - lots of phagocytes
B in follicles too
cutaneous and mucosal immune tissues
cutaneous under epithelium
mucosal in GI and respiratory tracts (peyers patches and pharyngeal tonsils)
T lymph maturation
matures in thymus
migrate to lymph nodes through HEVs
activated by macrophages or other APCs presenting antigens
they then differentiate and proliferate and migrate into tissues colonized by infectious microbes
high endothelial venules (HEVs)
mature t lymphocytes migrate into lymph nodes through them
express carbohydrate ligands that bind to L-selectin receptor on naive T cells so that the naive T cells bind losely to HEVs
cytokines expressed in paracortical regions induce t cells to bind more finally to HEVs and migrate through
