b cell activation Flashcards
what is first ig produced in immune response ?
igM
what is most abundant Ig in the blood, lymph and tissues?
igG
The _____________ is mediated by B-2 B cells binding to TD antigens.
T-dependent response
_____________ express _____________ concentrations of transcription factors known to be important in the maintenance of the cellular resting state (quiescence); they are therefore more effectively “poised” to enter the cell cycle.
memory B cells; lower
affinity
strength of binding of 1 Fab region and the antigen; usually high for bi-valent ig
avidity
total affinity of 1 antibody
where does SHM occurs?
Dark zone
what regulates class switch recombination? this causes a change in _____
Cytokines released by T-cells. Change in isotype produced by B cell.
Class switch recombination (CSR) is instigated by activation-induced cytidine deaminase (AID), which converts cytosines in S regions to uracils. The uracils are subsequently removed by two DNA repair pathways, resulting in mutations, single-strand DNA breaks, and the double-strand breaks required for CSR.
igM is a _____ where each monomeric unit is joined by _______
pentamer, disulfide bonds
igM is found in _____ and its function is to ? (Theres 3 mentionned)
blood
most efficient ig for activating complement system
ag agglutination
natural antibodies
low affinity since it doesnt need class switch recombination to form
igG has the ______ half life and has _____ subclasses
also is important in what function?
longest, four
agglutination (neutrilizes toxinx, immobilizes bacteria, neutralizes viruses)
opsonization
ADCC
Activates complement
Produced in memeory response
what Ig is able to cross the placenta ?
igG is passed to newborns via colostrum
what ig is produced in memory response ?
igG
what Ig is major in secretions (mucus, saliva, treas, milk)?
igA
igA exists as a ______ in secretions and ______ in serum
dimer; monomer
igA has ______ subclasses and is important asa primary defense against :
two
local respiratory or gastro-intestinal infections
what ig functions in phacocytosis, agglutination, prevents attachement to epithelial surfaces , ACDCC and degranulation?
igA
activated B-cells are called:
centroblast
proliferating B cells are called
centrocytes
of all ig’s, _____ has the shortest half life and is in lowest conc. in the serum
igE
what ig plays an important role in protection against parasites, and has an FC region with high affinity to receptors on mast cells and basophils ( allergen)?
igE
what ig is found in upper respiratory tract secretions?
igD
what two ig binds to mast cells and basophils?
igD and IgE
what ig’s are coexpressed on the surface of mature, naive B cells?
igM and IgD where igD>igM
upon binding of antigen, this ig causes increase release in antimicorbial peptides and cytokines
igD
when igE + allergen complex bind to the Fc receptor specific for igE on a mast cell, _______ causes the release of granule contents such as _______ that mediate allergic reactions
degranulation;histamine
what reactions involve Fc receptors binding to Fc domains of Abs?
transcytosis,
ADCC,
Opsonization and phagocytosis, activation of complement. degranulation
in class switch recombination, what makes double-strand breaks in the switch (S) region?
AID (activation induced deaminase)
differential RNA processing determines whether igM or igD is expressed since
cells cannot switch from igM and igD since there is no switch after cdelta
igM is produced since
C mu is the first after VDJ
a cell that can make igM can also make
igD
in a naive B cell the membrane ig include
igM and igD
compared to memory cells, naive B cells have a lag time of ______ and a time of peak response of
4-7 days
7-10 days
compared to naive B cells, memory B cells have a lag time of ______ and a time of peak response of ______
1-3 days
3-5 days
in a memory B cell what igG predominates?
igG
naive B cells have a _____ antibody affinity while memory B cells have a _____ antibody affinity
low;high
compared to memory b cells, naive b cells life span is ______ lived
short (days to weeks) while memory is up to the life span of animal host
The secondary response to antigen is drastically higher for what ig?
igG
T-dependent antigens produce
memory B cells
membrane ig of memory b cells
igM, IgG, igA or igE
anatomical circulation of naive B cells is ________ and memory B cells is________
spleen, LN, corculation,
circulation throughout the body
all proteins are _______ while carbohydrates, lipids and nucleic acids are often not_______
immunogenic
what are the requirements for immunogenicity?
- foreignness
- high molecular weight
- chemical complexity
- degradability
the more _____ a substance, the ____ immunogenic
foreign
more
how can a molecule with lower molecular weight become immunogenic?
coupling it with a larger carrier compound
T cells recognize antigens how?
only after they have been processed by APCs
how do APCs degrade antigens ?
since APCs express major histocompatibility complex class I and II, they enzymatically degrade antigens into antigenic peptides (4-10 aa in length) which bind to MHC for presentation to T cells
isotypic determinants
different epitotes help us determine ig isotype
allotypic determinants
same ig antibody isotype from different strains
idiotypic determinants
same ig isotypes but different CDRs
strongest response is from what route of antigen administration?
subcantaneous
adjuvants
substances that enhance immune response against the immunogen when mixed with an immunogen
the only adjuvant allowed to be used in humans is
aluminum potassium sulfate.
injection of rabbit igA against mouse would generate antibodies against?
rabbit j chain, rabbit alpha heavy chain
how is BCR signalling shut down?
CD22 OR FcgammaRIIB which comatin ITIMS
activation of SHP-1 would have what immediate effect downstream of BCR activation?
dephosphorylation of ITAMS
how do B-10 B cells act as negative regulators ?
secrete il-10 which shuts down inflammatory responses by T cells and APCs
