Lecture 12 and 13, Adaptive immunity Flashcards
What recognizes foreign material and proliferate
lymphocytes
What are the 3 characteristics of adaptive immunity
molecular specificity, memory, tolerance
What is molecular specificity
can differentiate among unlimited numbers of infecting agents
Memory has a stronger response to _______
re-exposure
What does vaccination rely upon
memory
what is tolerance
Must distinguish between what is healthy self and what is dangerous
What is the first response to an antigen called
primary response
the stronger _______ reponse results with subsequent exposure
secondary
What is humoral immunity
Anti-body mediated, eliminates extracellular antigens
What cell does humoral immunity involve
B cells
What is cell mediated immunity
antigens residing within a host cell
eg virus-infected cells, cancer cells
What cell does CMI involve
T cells
What is naive lymphocyte
has never encountered antigen, cannot react until it received confirming signals
What is activated lymphocyte
Has received confirming signals from dendritic cell expressing cognate antigen, proliferates, deifferentiates
effector lymphocyte
short-lived, primary response
memory lymphocyte
long-lived, activated more quickly to provide secondary response
in humoral immunity, activated B cells differentiate into _______ cells in response to extracellular antigens
plasma
activated B cells produce _______
antibodies
The stem of the antibody is what
red flag, marks bound antigen for elimination
What does B cell receptor do?
recognizes antigen by membrane bound antibody, must receive T cell signal to proliferate for same antigen
CMI
what eliminates antigens?
two subsets of T cells
CMI
what cell destroys corrupted host cells?
cytotoxic T cell
CMI
What cell directs/assists adaptive immune responses
helper T cell
CMI
both T cells have _______ analagous to BCR
T- cell receptors TCR
TCR does NOT
recognize free antigen, antigen must be presented by body’s own cell
_______ and _______ must be activated before they can multiply
helper T cells and cytotoxic T cells
_______ cells are responsible for T cell activation
dendritic
CMI
Once activated, T cell proliferates
forms _______ or _______
Effector helper T cells or effector cytotoxic T cells
Tc cells respond to _______
intracellular antigens
Tc cells induce cell to undergo _______
apoptosis
T h cells activate _______
B cells, macrophages, produce cytokines to direct and support other cells
regulatory T cells do what
stop immune system from overreacting and responding to harmless substance
_______ cells play a crucial role in activation of naive Th and Tc cells
dendritic
Where do dendritic cells reside?
peripheral tissue
Dendritic cells can send extensions between what?
epithelial cells of mucosal barriers and sample material in respiratory tract and lumen of intestine
What do toll like receptors do?
recognize pathogens
if TLR detects pathogen, what happens?
cell takes up more material
TLRs travel to _______, matures
secondary lymphoid organs
TLRs produce _______ signaling danger
co-simulatory molecules
TLRs present antigens on both _______
MHC class I and II
T cell is activated by the dendritic cell expressing what?
cognate antigen, as part of MHS calls I or class II and co-simulatory molecules
only T cells which can respond to _______ are allowed to mature
antigens presented by class I or class II
B cells and T cells have _______receptors
Membrane bound
_______ does not recognize free antigen, must be presented by body’s own cells
TCR
lymphatic system brings populations of lymphocytes in contact with _______
antigens
lymphatic vessels carry
lymph
Lymph contains antigens from _______
tissues
lymph flows through _______ before emptying back in circulatory system
lymph nodes
inflammatory causes what to happen to lymph
more fluid to enter tissues, increases antigen containing fluids entering lymphatic system
Primary lymphoid organs include
bone marry, thymus
_______ reside in bone marrow, give rise to all blood cells
hematopoietic stem cells
_______ cells mature into bone marrow
B cells
_______ cells migrate to thymus and mature
T cells
once mature, lymphocytes gather in _______ and wait to encounter antigen
secondary lymphoid organs
What are secondary lymphoid organs
lymph nodes, spleen, tonsils
_______ allow sampling of intestinal contents
peyer’s patch
peyer’s patch sample intestinal contents via what cells/
M cells, dendritic cells
Peyers patch is part of
MALT
mucosa associated lymphoid tissue
_______ prevents microbial invasion via mucous membrane
mucosal immunity
lymphoid tissues under skin are
SALT
skin associated lymphoid tissue
Antigen comes from
Antibody generator
What are T-dependent antigens
B cells requires confirmation from Th cells to be activated, protein componenet
T independent antigens can activate B cells without
Th cell help, include Lipopolysaccharide and molecules with repeating subunits
Antigen that elicit immune response is
immunogenic
_______ are more immunongenic than nucleic acids or lipids
proteins
_______ are usually not immunogenic
small molecules
what are epitopes
distinct regions of molecules
epitopes can be stretches of 10 _______
amino acids
Bacterial cells posses many different _______
epitopes
antibodies are also called
immunoglobins
what shape is an antibody
Y shaped
On an antibody, what are the two identical arms called
Fab regions
What do fab regions do
bind antigen
What is the stem of the antibody called
Fc region
What part of antibody can be crystallized
Fc region
Light chains have how many amino acid folds
2
Heavy chains have how many amino acid folds
4
Fork of Y is _______ region
flexiible hinge
_______ bonds join heavy, light chains and two halves
Disulfide
_______ region at ends of fab regions accounts for specificity
variable region
Antigen binding site attaches to _______
epitope
constant region inclues
Fc and two Fab regions
Neutralization
prevents toxins, viruses from binding
opsonization
enhancement of phagocytosis
complement system activation
classical pathway
immobilization and prevention of adherence
binding to bacterial flagella or pili interferes
cross linking
two arms of antigen bind separate antigens
antibody dependent cellular cytotoxicity (ADCC)
targets cell for destruction by natural killer (NK) cells
five major classes of immunoglobulin
igM, igG, igD, igE
IgM is produced when
during primary response
IgM is produced in response to ______
T-independent antigens
IgM is what type of subunit?
pentamer, 5 subunits
Pentamers ______ very effecitvely
aggregate
Larger size of IgM prevents what
crossing from bloodstream to tissue
IgM is primary role is
Bloodstream infection
which antibody is the most abundant?
IgG
igG provides
longest term protection
How does igG protect?
via neutralization, aggregation, opsonization, complement activation
IgG is transported across ______ to ______
placenta to fetus’s bloodstream
What does maternal IgG do?
protects fetus and newborn?
IgG is found in ______
colostrum (first breast milk)
IgG is absorbed by newborn’s ______
intestinal tract
most IgA is a dimer which is
secretory IgA (sIgA)
IgA is important for what?
mucosal immunity
how does IgA protect?
via neutralizing toxins, viruses, interfering with attachment of microbes
What is IgA produced by
Plasma cells of MALT
What antibody is the least common?
IgD
What is IgD involved with?
development and maturation of antibody resposen
How prevalent is IgE?
barely detectable in serum, tightly bound in Fc region
What do antigens do to IgE?
they bind two adjacent IgE molecules carried by mast cell
IgE is important in eliminating what
parasitic worms
How is allergies related to IgE?
basophils and mast cells release chemicals when IgE binds to harmless foods and cause reaction
Colonal selection applies to what cell?
B cells and T cells
lymphocytes residing in secondary lymphoid organs wait for ______
Antigen with correct epitope
immature lymphocytes
lack fully developed antigen specific receptors
Naive lymphocytes
have receptors, have not yet encountered appropriate antigen
activated lymphocytes
have bound antigen and received confirmation, are able to proliferate
effector lymphocytes
descendents of activated lymphocytes:
plasma cells, Tc cells, Th cells
Memory lymphocytes
long-lived descendants of activated lymphocytes; responsible for rapid secondary response if antigen is encountered again
B cell is activated by ______ antigens
T-dependent
the fragments of the antigen from B cell receptor is delivered to ______
MHC class II molecules for inspection by Th cells: antigen presentation
If T cell receptor binds a fragment, T cell activates B cell with cytokines and initiates ______
Clonal expansion
If no Th cell recognizes peptides, B cell becomes ______
Anergic
What does anergic result in
tolerance to antigen
how many days does it take for the antibody accumulation after first exposure
10 to 14
in primary response, ______ cells continue proliferating and differentiating in presence of antigen, so antibody titer increases
Activated B cells
in primary response, ______ cells undergo changes that result in production of more effective antibodies
Proliferating B cells
What is affinity maturation
spontaneous mutation occurs in multiplying B cells resulting in changes in B cell receptor
B cells that bind antigen longest proliferate
What is class switching
Plasma cells normally secrete IgM, Th cells induce B cells to become plasma cells that secrete other antibody classes
B cells in lymph nodes switch to
IgG
B cells in MALT switch to
IgA
After class switching, ______ cells are formed
memory
