VDJ B cell recombination Flashcards
as B cells proliferate following ANTIGEN CONTACT at secondary LYMPHOID ORGANS, mutations occur PREFERENTALLY in the VDJheavy and VJlight genes, this process if called….
somatic hypermutation
B cells at secondary lymphoid organs who are trying to figure what’s the antigen binding site they should have, mutates its antigen binding sites, if these altered ab failed to bind antigen……
B cell dies
B cells at secondary lymphoid organs, if they mutate their antigen binding sites that bind antigen better than the original, these B cells….
receive stronger signals to proliferate and mature into PLASMA CELLS
As immune reponse progresses, the average affinity of the responding B cells and antibody produced in 2NDARY LYMPHOID ORGANS…….
INCREASES this is called AFFINITY MATURATION
Isotype switching increases the………of ab molecules
FUNCTIONAL DIVERSITY
Isotype switching deals with the ……of the ab, where as somatic hypermutation invovlves…….
ISOTYPE FUNCTIONAL DIVERSITY
SOMATIC HYPERMUTATION mutating its antigen binding sites of Ig to increase the ab affinity to the antigen its presented to
When does isotype switching occur……
occurs following ANTIGEN stimulation and TH2 cytokine production
List CH genes in linear order
C mu, C delta, C gama3, Cgama1, PSEUDOGENE C epsilon, C alpha 1, C gama 2, Cgama 4, Cepsilon, and Calpha 2
Each C gene segment except….. is preceded by an intron containg a ……sequence
C delta
SWITCH REGION
Switch sequences differ from recombination signal sequences found flanking V regions seg
True
switch sequences introns, don’t code for nonsense
in vdj you can get nonsense nonfunctional parts
Rearranged VDJHeavy is always expressed……with membrane…..
FIRST…Cmu or IgM
Mature B celll has…
BOTH MEMBRANE C(mu) and C(delta)
As B cell begins to respond to antigen it secretes……
SECRETED C mu IgM
What causes B cells to switch isotopes…..
receiving CYTOKINES
The DNA between two switch regions that are recobminating are…..
lopped out and removed from genome
All…..are productive since DNA spllicing occurs w/in ……so non nonsense codons are NOT introduced into the transcribed DNA
PRODUCTIVE
SPLICING OCCURS in INTRONS
Further switches to down stream isotypes IgA and IgE may occur if the B cell receives the required…..
cytokine signal
Genes for ig are UNLIKE other human genes in that
a) each polypeptide chain is encoded by several exons.
b) Ig genes are composed of introns and exons
c) somatic recombination occurs before mRNA is transcribed
d) there is less Ig genetic material in mature B cells than in other somatic cells
c) somatic recombination occurs before mRNA is transcribed
d) there is less Ig genetic material in mature B cells than in other somatic cells
Somatic recombination results in loss of DNA.
CH (Cheavy) affects the……but not the…..
biological functions but NOT antigen-binding specificity of the ab
Which does NOT contribute to Ig antigen-binding diversity
a. Any L chain can combine with any H
chain to form a functional antibody.
b. Any Vk can be joined to any Jk to encode the light chain V region.
c. Many CH genes are present in the germline DNA.
d. Random numbers of N nucleotides can be added during somatic recombination.
e. VJL and VDJH joining is imprecise.
c. Many CH genes are present in the germline DNA.
List 4 things that contribute to Ig ANTIGEN BINDING DIVERSITY
Any L chain can combine with any H
chain to form a functional antibody.
Any Vkappa can be joined to any Jkappa to encode the light chain V region.
Random numbers of N nucleotides can be added during somatic recombination.
VJL and VDJH joining is imprecise.
The proper joining of one VL to one JL is regulated by…..
12 and 23 nucleotide spacers between heptamer and nonamer sequences.
Clonal selection is the…..
availability of a mechanism to focus the antigen to the appropriate B cells and enable the stimulation of those B cells
Most cells of the vertebrate species have a diploid chromosomal organization and express both alleles of an active gene. The ….. are an exception to this rule because only ONE of their alleles is expressed as a FUNCTIONAL product.
Ig and TCR
Since each B cell productively rearranges a single H and L chain allele, it exhibits
a. affinity.
b. allelic exclusion
c. antibody restriction.
d. antigen-binding diversity.
e. cross-reactivity
b. allelic exclusion
Productively rearranging only one H and one L chain means that a single B cell makes antibodies with only one allotype and one antigen-binding specificity.
B cells must express an …..before they can mature and leave the marrow.
antigen receptor
where they travel to lymph nodes to meet antigens, and are activated go to the germinal centers and proliferate. Once they become plasma cells, they go back to the bone marrow.
Somatic recombination occurs
a. in the bone marrow stem cell.
b. in the progenitor cell as it is becoming a B cell.
c. in the mature B cell following antigen contact.
d. in the plasma cell after antigen contact.
e. in the plasma cell after antibody secretion.
b. in the progenitor cell as it is becoming a B cell.
the reason why its not a is because it said stem cell, stem cell which is incorrect
Somatic recombination occur prior to the B cell coming in contact with antigen, occurs in the bone marrow
once B cells have their BCR and are matured,naive B cells
they travel to the secondary lymphocytes and interact with their antigens and T helper cells, then they go to germinal centers to proliferate and differentiate
once they are plasma cells they return to their bone marrow
Plasma cells are effector cells and actually express little…..
MEMBRANE IG
Diversity comes from many different antigen-binding sequences; each B cell expresses
ONLY ONE
Cross-reactivity depends on
two antigens having similar epitopes, not on somatic recombination.
Isotype switching
a. changes the leader sequence exon so the antibody is secreted.
b. improves the antigen binding specificity of an Ig molecule.
c. increases the affinity of antibodies in a process called affinity maturation.
d. increases the functional diversity of Ig molecules.
e. occurs randomly between switch regions.
d. increases the functional diversity of Ig molecules.
Secretion versus membrane-bound Ig depends on which
CH exons are in the final message.
Different isotypes have different biological functions but they can have the same
antigen-binding specificity.
Isotype switching occurs at switch sites and is regulated by
helper T cell cytokines along with their cytokines to tell the B cell to secrete what kind of ab
Isotype switching resembles somatic recombination because both processes
a. are catalyzed by the products of RAG1 and RAG2
b. are regulated by helper T cell cytokines.
c. can result in stop codons in coding sequences.
d. occur in developing B cells in the bone marrow.
e. result in the irreversible loss of DNA from the B cell.
e. result in the irreversible loss of DNA from the B cell.
Both processed result in looping out of DNA.
Rag-1 and RAG-2 products catalyzes
antigen binding specificity
T cell cytokines do not…..
Regulated somatic recombination
since somatic recombination occurs prior to B cell meeting the antigen, engulfing, and presenting it as an APC for a T helper cell come along bind to it and secrete the necessary cytokines for the B cell differentiate into a plasma cell and start secreting high affinity antibodies
Splicing between gene segments is imprecise, sometimes resulting in nonproductive rearrangements in which
frame shift mutations yield stop codons downstream and no complete H or L chain can be produced.
Products of what genes are required for somatic recombination
two recombination-activating genes, RAG-1 and RAG-2
enzymes to ligate (reattach) the DNA
terminal deoxynucleotidyl transferase (TdT)
Junctional diversity affects primarily the amino acid sequence in
a. all CDR equally.
b. CDR1.
c. CDR2.
d. CDR3.
e. FR3.
d. CDR3.
Only ……..can be produced simultaneously. ………require isotype switching during which exons for mu and delta are lost. Select another answer.
IgM and IgD can be SIMULTANEOUSLY produced
IgG, IgA, and IgE need ISOTYPE SWITCHING
Alternative mRNA splicing occurs
> IMMATURE B CELLS
> IN BONE MARROW
> W/OUT T CELL HELP
.Alternative mRNA splicing
a. allows the B cell to improve its antigen-binding fit after antigen contact.
b. allows the B cell to make membrane IgM from the mature mRNA for secreted IgD.
c. can be used for the simultaneous production of any two Ig isotypes.
d. is a process by which a B cell can simultaneously synthesize m and d chains.
e. occurs in response to T cell cytokines.
d. is a process by which a B cell can simultaneously synthesize m and d chains.
Because of the order of the CH gene segments (Cm, Cd, Cg3, Cg1, pseudogene Ce, Ca1, Cg2, Cg4, Ce, and Ca2), a human B cell which undergoes isotype switching from IgM to IgG1 can never in the future secrete
a. IgA.
b. IgE.
c. IgG2.
d. IgG3.
e. IgG4.
d. IgG3.
The gamma 3 exon is upstream from gamma 1 and is lost in the isotype switch.
Gene recombination and DNA loss is part of isotype switching.
True
DNA between the former CH and the new CH is lost.
True
B cells can only produce…and… simultaneously.
IgM and IgD
via alternate splicing
other antibodies IgE, IgG, IgA have to undergo isotype switching
Isotype switching is always productive because
a. B cells produce all isotypes simultaneously.
b. isotype switching does not involve recombination of DNA gene segments.
c. no DNA is deleted from the chromosome in isotype switching.
d. no effector diversity results from isotype switching.
e. recombination between switch sites occurs in introns so it cannot introduce stop codons into coding regions.
e. recombination between switch sites occurs in introns so it cannot introduce stop codons into coding regions.
which is different from the VDJ/VJ variable binding regions where stop condons do occur in exons and results in a non-functional
Many B cells undergo unfavorable mutations and
die because they can no longer bind antigen.
Somatic hypermutation
1) occurs during B cell proliferatioin
2) occurs in B cell FOLLOWING antigen stimuation
3) result in increased affinity of ab secreted later in immune responses
4) result in death of some B cells which non longer bind antigen
Somatic hypermutation…. in the B cell which has bound antigen.
does occur
- IMPORTANT
Somatic Recombination is NOT THE SAME AS somatic hypermutation in that.
> somatic recombination occurs PRIOR to antigen contact, during B cell development in BONE MARROW
> somatic HYPERMUTATION generates Ig diversity AFTER B cell has matured and migrated to the SECOND LYMPHOID ORGANS
- as B cells proliferate follwing antigen contact, mutations occur PREFERENTIALLY in VDJ, and VJ
In which of the following ways does the developmental pathway of α:β T cells differ from that of B cells? (Select all that apply.)
a. Their antigen receptors are derived from gene rearrangement processes.
b. When the first chain of the antigen receptor is produced it combines with a surrogate chain.
c. Cells bearing self-reactive antigen receptors undergo apoptosis.
d. MHC molecules are required to facilitate progression through the developmental pathway.
e. T cells do not rearrange their antigen-receptor genes in the bone marrow.
d. MHC molecules are required to facilitate progression through the developmental pathway.
e. T cells do not rearrange their antigen-receptor genes in the bone marrow.
they rearrange them in the THYMUS
Which of the following is the first stage of T-cell receptor gene rearrangement in α:β T cells?
a. Vα→Dα
b. Dα →Jα
c. Vβ→ Dβ
d. Dβ→Jβ
e. Vα→Jα.
d. Dβ→Jβ
______ of thymocytes is necessary to produce a T-cell repertoire capable of interacting with self-MHC molecules.
a. positive selection
b. negative selection
c. apoptosis
d. receptor editing
e. isotype switching.
a. positive selection
T-cell receptor binds strongly to self-peptides presented by self-MHC molecules,the thymocyte will be ……selected.
NEGATIVELY
T-cell who don’t recognize MHC molecules of the thymic epithelium will result in ….selection
POSTIVE
T-cell receptors may be autoreactive but escape ………..selection because its peptide antigen is ……..
NEGATIVE selection
its peptide antigen is present in tissues OTHER THAN THE THYMUS
Thymocytes that are not positively selected
make up about 98% of developing thymocytes and die by apoptosis in the thymic cortex
***All of the following types of protein are processed and presented by macrophages in the thymus except _____ proteins.
a. tissue-specific
b. soluble proteins from extracellular fluids
c. ubiquitous proteins
d. proteins made by macrophages
e. proteins derived from other cells that macrophages phagocytose
a. tissue-specific
this is important because thymocytes who are auto reactive to self peptides might escape negative selection if their self-tissue antigen isn’t present in the thymus
The function of negative selection of thymocytes in the thymus is to eliminate
a. single-positive thymocytes
b. double-positive thymocytes
c. alloreactive thymocytes
d. autoreactive thymocytes
e. apoptotic thymocytes.
d. autoreactive thymocytes
The human thymus begins to degenerate as early as one year after birth. This process is called______ and is marked by the accumulation of ___ once occupied by thymocytes.
a. thymectomy; dendritic cells
b. involution; fat
c. differentiation; γ:δ T cells
d. negative selection; γ:δ T cellse. involution; thymic stroma
b. involution; fat
The human thymus begins to degenerate as early as one year after birth. This process is called______ and is marked by the accumulation of ___ once occupied by thymocytes.
a. thymectomy; dendritic cells
b. involution; fat
c. differentiation; γ:δ T cells
d. negative selection; γ:δ T cellse. involution; thymic stroma
b. involution; fat
mature, naive B cells develop into Plasma cells in the
a. subendosteum
b. bone marrow
c. thymus
d. blood
e. secondary lymphoid organs.
e. secondary lymphoid organs.
Place the following phases of a B cell’s life history in the correct chronological order.
a. negative selection
b. attacking infection
c. finding infection
d. searching for infection
e. repertoire assembly
f. positive selection.
repertoire assembly
negative selection
positive selection
searching for infection
finding infection
attacking infection
Place the following stages of B-cell development in the correct chronological order.
a. early pro-B cell
b. large pre-B cell
c. immature B cell
d. stem cell
e. late pro-B cell
f. small pre-B cell.
stem cell >
early pro-B cell >
late pre-B cell >
large pre-B cell >
small pre-B cell>
immature B cell
The consequence of allelic exclusion at the immunoglobulin loci ensures that _____.
B cells express antigen receptors of a SINGLE SPECIFICITY
homogeneous B-cell receptors bind more effectively to antigen
Receptor editing occurs for B cells in the…….
bone marrow
to establish self tolerant repertoire
List 4 properties of plasma cells
1) terminally differentiated B cells meaning they can’t divide anymore and are short lived
2) NO longer express MHC II
3) cease expressing membrane bound Ig
4) differentiate into plasma cells after migration from germinal center of lymphoid tissue and bone marrow
Thymus independent antigen is…..as Thymus-dependent antigen
Thymus independent antigen is NOT as effective as Thymus Dependent
IgM is the…. after antigen exposure
First ig
IgM
1) PENTMAERIC in SECRETED form
2) stays in serum, too large to go to tissue
3) ANTIBACTERICIDAL, complement-binding antibody
4) RA autoantibody of IgG’s Fc
5) MONOMERIC in MEMBMRANE form
6) first antibody produced ruing intial exposure to antigen, primary response
transiently expressed after infection therefore ordering lab tests for IgM is a good idea after a recent exposure to pathogen
to test it pt has immunity for a certain pathogen, use IgG which remains in serum months and years after exposure. placenta also
IgA is to test for mucosal immunity in GI tract, Airways, and Lungs since its in secretion, IgA can exist as a dimer in secretions
IgE is for allergic reactions, inducing mast cells to release granules, or parasitic infections.
IgG
1) Major isotype of circulating serum antibody, longest half life
2) ONLY isotype to cross placenta
3) fixes complement, acts as OPSONIN
4) stimulates chemotaxis
IgA
1) predominant antibody on EXTERNAL SECRETIONS (saliva, mucus, breast milk)
2) mono mostly in serum and DIMER in secretion
3) PREVENTS adherence of microbes to mucus membranes
IgE
1) TYPE I IMMEDIATE hypersensitivity
2) Antiparasitic
3) Binds tightly to Fc receptor on Mast cells
All antibodies produced by an individual B cell have the same antigenic specificity
True
Light chain gene has
VJC segments
either get JVC recombination on KAPPA
or
either get JVC recombination on LAMBDA
Heavy chain gene has
VDJC segments
B cells require …… to respond to most antigens
T HELPER Cells and CYTOKINES
For T dependent stimulation, describe the costimulatory signal
T helper’s cell’s CD40L bind to CD40 on B cells promotes increased expression of cytokine receptors on B cell
For T dependent stimulation, coreceptors….and…instensify initial signal triggered by antigen binding
CD21 and CD19 on B cell
For T dependent stimualtion, describe cytokine signals
B cell differentiate after binding to cytokines secreted by T H cells
plasma cells are terminally differentiate B cell that SECRETE antibody
Memory B cells which express MEMBRANE bound ab of any isotype respond FASTER than naive B cells to second exposure to antigen
Antibody effector mechanisms List 3
1) Neutralization of viruses and toxins
when agents become coated with ab, which intereferes with their binding to receptors,preventing infectious/toxic process from proceedding
2) opsonization IgG
promotes ingestion and killing by phagocytic cells
3)Complement Activation IgG and IgM
induces inflammatory response and cytolytic destruction of extracellular microbes
1) Neutralization of viruses and toxins
when agents become coated with ab, which intereferes with their binding to receptors,preventing infectious/toxic process from proceedding
2) opsonization IgG
promotes ingestion and killing by phagocytic cells
3)Complement Activation IgG and IgM
induces inflammatory response and cytolytic destruction of extracellular microbes
Explain the difference b/w BCR and antibodies
C terminus of the HEAVY CHAIN for BCR is HYDROPHOBIC
C terminus for the HEAVY CHAIN ab is HYDROPHILLIC
Light Chain has ……but a single immunoglobulin uses only……
Light Chain has lambda or kappa but a single immunoglobulin uses only lambda OR kappa, NOT BOTH
On lambda light chain genes, there’s V and J and C
On KAPPA light chains, there’s V, J, and C
***Papin digestion celaves antibody into
two FAB fragments and ONE Fc fragment
Pepsin digestion celaves ab into
Separates the FAB fragments from the Fc fragments, but the FAB fragments are still bound together even after the seperation
Hypervariable regions of ig and TCR corresponds to….
antigen-binding regions
*****Antibodies antigens can be anything that can bind anywhere on the antibody’s variable region (doesn’t have to be the pocket like MHC) and they don’t even have to be peptides.
True
Antibodies recognize both
1) specific sequences
2) structural shape
how do antigens bind ig?
1) electrostatic forces (positive charge with negative charge)
2) hydrogen bonds
3) van der waals
4) hydrophobic forces, hydrophobic molecules pack together in unfavorable water environment also involves van der waals
Describe how somatic recombination (not somatic hypermutation which occurs after antigen and t cell meet with b cell) works….
1) RAG binds and cleaves to yield a DNA hairpin
2) RAG cleaves the hairpain to generate PALINDROMIC P-nucleotides (two strands bind to each other but if read them the same direction they are identitical)
3) N-nulceotide additions by Tdt
4) pairing of strands
5) unpaired nucleotides are removed by exonulcease
6) gaps gaps are filled by DNA synthesis and ligation to form coding joint
Somatic hypermutation is specific to the
1) Ig sequences and not for other genes in the same activated B cell
2) increases following B cell activation and is assoc with B cell proliferation events
Early pro B-cell
DJ rearranging on H chain
Late pro B-cell
V-DJ rearranging on H chain
Large pre-B cell
VDJ arranged
mu chain transiently at surface as part of pre-B cell receptor mainly intracelluar
Small pre-B cell
V-J rearranging in L chain
itracellular mu chain
Immature B cell
VDJ rearranged
VJ rearranged
IgM expressed on cell surface
NOT YET for IgD, this happens in MATURE naive B cells
***Mature B cell
IgD and igM made from alternatively spliced H chain transcripts
Generation of B cell receptors occur in
the BONE MARROW
Negative selection of B cells occurs in the
BONE MARROW
Which antibody is generally lower affinity than later isotypes?
IgM
Which two antibodies can form multiplers?
IgM as a pentamer in serum
IgA as a dimer in secretions
Avidity
Total binding strength
Why do antibodies polymerize?
Binding of repetitive epitopes increases avidity (total binding strength) which partially offsets/compensates for lower affinity
THEY COMPENSATE FOR THEIR LOWER AFFINITY WITH AVIDITY BY POLYMERIZING
I”M LOOKING AT YOU IGM
How do IgM get around being lower affinity than other antibodies?
It increases its avidity, binding strength by polymerizing so it can bind repetitive epitotoes which increases its avidity and offsetting its lower affinity
Are the first isotype(s) generated and are alternate spliced products of the same immature RNA transript transcribed from a single gene
IgM and IgD
Which Isotypes are generated by isotype switching
IgG, IgE, IgA
mature, Naive B cells express
IgM and IgD
When B Cells are activated they cease to express….
IgD
and
initially produce and secrete SERUM IgM
IgM was switched to IgE from cytokine signals do they still recognize the same antigen epitope?
yes, isotype switching does not affect antigen binding variable region
the ag:ab now triggers a DIFFERENT FUNCTION via the new constant region
B cells can undergo isotype switching….following additional activation
MORE THAN ONCE
When VDJ is moved to constant region gamma the b cell makes
IgG
WHen VDJ is moved to constant region alpha, the b cell makes
IgA
V region assembly
what is the process:
is it reversible/irreversible?
Does it occur on B cells
Does it occur on T cells
V region assembly
SOMATIC recombination (NOT SOMATIC HYPERMUTATION WHICH ONLY OCCURS IN B CELLS)
IRREversible
B Cell YES
T Cells Yes
Junctional Diversity
process
reversible/irreversible
Does it occur on B cells
Does it occur on T cells
Junctional Diversity
IMPRECISE joining, N-sequence insertion in DNA (joining of alpha to beta or, light chain to heavy chain)
IRREversible
B cells YES
T cells YES
Transcriptional Activation
process
reversible/irreversible
B cells?
T cells?
Transcriptional Activation
ACTIVATION of PROMOTER by proxmimity to the enhancer
B cells YES
T cells YES
VERY IMPORTANT
hypermutation does it occur in both B cell and T cell?
NONONONONONO!!!!!
Somatic HYPERmutation occurs ONLY IN B CELL
Is IgM and IgD expression on surface reversible or irreversible?
Reversible
DIfferential splicing of RNA
Is Membrane vs secreted form for Ig reversible or irreversible?
Reversible
Differntial splicing of RNA
**Cytokine expression regulates antibody…..
isotype switching
Where do activated B cells proliferate?
In the lymph nodes, specificallythe GERMINAL ZONES in spleen, lymph nodes, or inflammation sites
When B cells differentiate into plasma they go to the….
BONE MARROW
When do B cells express MHC II?
when it is resting B cell (doesn’t secrete Ig)
or as PLASMABLAST (secretes Ig)
Do plasma cells have MHC II?
No
When can B cells undergo somatic hypermutation and increase ab affinity?
1) naive Resting b cell
or
2) MEMORY B cell
NEVER PLASMA B CELL, since its already become a antibody secreting factory, it cannot under go somatic hypermutation as it is a irreversible process and the plasma b cell has already gone through that
When can B cells still Isotype switch?
As a resting B cell, or Palsmablast
UNTIL IT CAN NO LONGER receive help from CD4 helper T cell, when it expresses MHC II
When do B cell not need CD4 T cell helper?
Plasma Cell
which are cell dedicated to secreting ab
1) does NOT have MHC II
2) cannot undergo somatic hypermutatoin
3) cannot isotype switch
Explain the difference between Th1 and Th2 CD4 cells
both are T helper cell
Th1 is involved in
1) macrophage activation
2) IgG secretion, IgG SECRETION, IgG SECRETION!!!!!!!
3) autoimmune disorders
Th2 is involved in
1) Mast Cell activation
2) Eosinophil activation
3) Allergic Reactions
4) parasites
B cells secreting IgE need which type of T cell?
1) Helper T cell
2) Helper 2 T cell, since IgE is involved in allergic rxn
What affects T helper cells differentiation into either Th1 or Th2?
1) Density of MHC II receptors for the T helper’s corresponding APC
APC has high density MHC II
TH1 is developed
APC has low density MHC II
TH2 is developed
why did I only write MHC II here and not the other MHC, because APC has MHC II
2) type of APC and co-stimulatory elements encounter by CD4 helper cell
3) Cytokine environment
IL4 and IL5 induces Th2 differentiation
Which cytokines induces Th2 differntiation?
IL4 and IL5
An APC has high density of MHC II being presented to CD4 T cell, which helper cell does it differntiates to?
Th1 helper CD4 T cell
APC presents peptide with weak binding to the T cell receptor, T cell differentiatates into a?
TH2 Cell
Apc presents peptide with STRONG binding to T cell receptor, T cell differentiates into a?
Th1 cell
Factors produced by Th1 and Th2 negatively cross regulate each other meaning that they?
Factors secreted by Th1 INHIBITS DIFFERENTIATION of Th2, and vice versa
Is helpful in diagnosing,….recent infections?
transient presence of IgM ab is helpful in dx RECENT infections
since other ab are higher affinity than IgM, IgM isn’t secreted any more when b cell meets its antigen, corresponding helper T cell, and receives cytokines from T cell to undergo isotype switching for a more higher affinity Ig
Recent infection will show IgM in blood serum, since IgM is first initially expressed before the B cell undergoes isotype switching to secrete a more specific antibody than a generalist IgM
You recently participated in a chicken pox party, your doctor orders both IgG and IgM test?
IgM to determine if there was a recent infection
IgG to see if you’ve built long lasting immunity
IgA is important for mucosal immunity
When you ask your doctor to test if you’re immune to certain pathogens and you’ve told him you’ve had vaccines before, why is it only necessary for him to check IgG?
IgG is ordered to see if you’ve build long lasting immunity
since
IgG remains detectable for months or YEARS
IgM become UNDETECTABLE following weeks/months after infection, its only useful to figure out if you’ve had a recent infection
IgG antibodies
1) inactivate toxins
2) opsonize bacteria
3) activate COMPLEMENT
3) neutrallize viruses and bacteria that CROSS THE PLACENTA
IgA are important in which body parts
mucosal immunity in the
1) GI tract
2) Nose
3) Lung
IgE fight
1) parasite
2) worms
3) CAUSES ALLERGIC RXN via activating MAST CELLS
Which antibody is really important in protecting the conceptus from viruses and bacteria across the placenta?
IgG
B cells must be first activated by their….before they can go to the germinal centers in lymph node and proliferate and differentiate into plasma cells
antigens and T helper cells
