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261 Cards in this Set

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  • Back
What are the two branches of immunity and how do they differ?
Innate and aquired immunity

Innate--born with, FAST acting, acts via barriers (skin), cells, and serum proteins

Aquired or adaptive--improves with exposure and is mediated by B and T cells
What is the first line of defense?
skin and mucous membranes
What is the second line of defense?
Phagocytosis by neutrophils and monocytes/macrophages

Complement activation: cell lysis, inflammation, opsonization (proteins stick to surface of microbe to tag it and signal the phagocytic cell.

calor, dolor(pain), rubor, tumor


Natural killer cells--lytic
How is fever helpful?
Raises temp which may allow enzymes to work more efficiently, increases generation time therefore decreasing replication of bacteria
What type of cell is a NK cell?
A NONSPECIFIC lymphocyte
What is the third line of defense?
Activation B and T lymphocytes
What do B cells do and what do they recognize?
B cells recognize cell bound OR soluble antigens (Ag)[RECOGNIZE ANTIGENS ANYWHERE]produce antibodies (Abs)
What is an antigen?
Anything that stimulates and immunologic response--an antibody generator

anti gen
What kind of immunity do B cells provide? T cells?
B cells--humoral mediated immunity
Ab mediated immunity

T cells--cell mediated immunity
What do T cells recognize and produce?
T cells recognize ONLY cell bound foreign molecules--antigens, they produce CYTOKINES to direct other cells
What type of cells produce cytokines?
Cytokines USUALLY produced by T cells, can also be produced by B cells and others.
Which type of response is specific? nonspecific?

What type of cells is the adaptive response due to?
B and T cells
What are the 4 main properties of aquired immunity?
1 recognition of self vs. non self

2. specificity

3. heterogeneity, adaptibility, diversity

4. memory--allows for quicker response (vaccine)
What happens to self reactive cells?
They should be destroyed early in the development of T and B cells

When they are not destroyed they undergo Ag tolerance

Can result in autoimmunity
Where do B cells mature? T Cells?
B cells in the bone marrow
T cells begin in bone marrow and then in the thymus

self reactive B cells destroyed in bone marrow; T cells in thymus
What is the top part of the Ab called and what is characteristic of it?
top is called the n terminal, it is the variable region
Is a T cell receptor membrane bound?
yes it is NOT secreted
Is an antibody secreted by a B cell or membrane bound?
What type of chains make up an antibody?
heavy and light

heavy and light on top and heavy below
What are the common types of B cell Ags?

What are the rare forms?
protein or carbohydrates

Nucleic acid and lipid
What autoimmune disease makes antibodies against DNA?
What configuration do B cells recognize antigens in?
B cells recognize soluble Ag, often in native configuration (i.e. NOT PROCESSED)
Are B cells good at recognizing extracellular Ags?
What configuration do T cells recognize antigens in?
T cells recognize processed Ag presented with the MHC--major histocompatibility complex
What is the function of a MHC?
A major histocompatibility complex binds to a piece of chopped up protein and sits on surface of cell for T cell receptor to recognize

Acts as a "flagpole"
What are the 2 classes of MHC's?
Class I CD8+
Class II CD4+
What are the 3 major types of MHC class II?
dendritic, macrophages, B cells
What does it mean for a protein to be "processed"?
To be chopped up
Will all peptides associate with the MHC? What does this correspond to?

Corresponds to the reason why some people respond well to infectious organisms and other do not.
What types of cells make a bridge between innate and adaptive immunity?
What job does each fulfill?
Antigen presenting cells (APC) present antigens to T cells. Activate T cells to produce cytokines

Professional APC's--macrophages, dendritic cells, and B cells. Present Ag in assoication with MHC class II.
Is there a gene for every Ag?
No. That would take up 60% of the genome.

The variable region determines specificity.
What is an immunoglobulin?
Same as an Ab
What is the V region? D? J?
V variable
D diversity
J joining genes

creative genetics
Do B cells or T cells exhibit memory?
What kind of response do memory cells allow for?
memory allows for quicker and better response when next recognizing an Ag
How long does an initial response take? A memory response?
initial (primary immune response)2 weeks
memory (secondary immune response)a few days
What happens to affinity with subsequent exposure in memory cells?
Increased affinity
What happens when a T or B cell recognizes an Ag?
It proliferates and goes to eliminate the pathogen
How do you measure a T cell primary and secondary response?

B cell?
T Cell measure cytokine response.

B cell measure antibody spike
Is the memory response fail proof?
No, remember chicken pox. Doesn't always work
What is the best type of vaccine? When can this cause problems?

Ex. small pox. People w/ weakened immune response can't fight off the weakened form and die
When would it be a good idea to use a heat or chemically killed microbe vaccination?
Use for people with weakened immune response. Will break bonds or proteins. might not work because of denaturation
What is a toxoid?
A type of vaccine. chemically teat a toxin so it doesn't have its function anymore. BUT retain its Antigenic determinants
What is the difference between passive and active immunity?
Passive is from antoher organism. Ex. mother IgA or purified gamma globulin from infected people or animals.

The BEST!! Active is from an individual's immune system and produces memeory cells.
In what disease could you vaccinate after infection?
Rabies. Takes a long time to get symptoms
What are some pathologies related to the immune response?
organ transplants, allergies, autoimmune response
What is a TCR? BCR?
A T cell receptor.
B cell receptor
What does a megakaryocyte become?
Breaks off to platelets
What are the 3 main blood type lineages?
lymphoid, myeloid, erythoid
What type of cells are natural killer cells? How do they differ from other lymphocytes?
NK's are NONSPECIFIC lymphocytes
What types of cells are formed from the erythroid lineage?
RBC's and platelets
What is a PMN? What do they usually refer to?
PMN = polymorphonuclear leukocytes. Usually refers to neutrophils.
What types of cells are formed from the myeloid lineage?
Granulocytes--PMN leukocytes
= neutrophils, eosinophils, basophils

Mast cells
What types of cells are formed from the lymphoid lineage?
lymphocytes, B and T AND NK cells
Do neutrophils activate T cells?
no doesn't have any CD4+ Class II
Are RBC's nucleated?
Not in mature RBC's
Which is better dendritic cell or macrophage?
dendritic cell because most effective at stimulating a T cell response
What is a plasma cell?
A B cell that produces antibody
If a patient has an increase in eosinophils what does that mean?
Either they have allergies or a parasitic worm infection
How is blood development directed?
By colony stimulating factors (CSF) and other cytokines
How are colony stimulating factors (CSF) and other cytokines activated? Where are they produced?
CSF's and other sytokines are activated by helper T (Th) cells and macrophages.

Produced by bone marrow stromal cells
What is type of WBC is the largest?
The monocyte
Where are macrophages found? What is the difference between monocytes and macrophages?
Macrophages are in the tissue. The monocyte is the precursor to the macrophage
What determines committment of distinct blood cell lineages?
Need the growth factor (CSF)AND the CSF receptor.
What are some types of CSF?
1. multilineage CSF--IL3 (IL=interleukin)
2. Granulocyte-Machrophage CSF (GM-CSF)
3. M-CSF
4. G-CSF
5. Erthropoietin (EPO)
Where is IL-3 produced and when does it act?
acts early and is produced by T cells and mast cells.
What does IL-6 do? Is it a CSF?
an inducer of hematopoiesis during infection. Produced in bone marrow cells, T cells, B cells, macrophages
Where does hematopoiesis occur? In adult?
In the yolk sac, then fetal liver, then fetal spleen. In adult in bone marrow. From about 4th month of life.
In adult in the long bones.
How long do RBC's live? Neutrophils? T Cells?
RBC's--120 days
Neutrophils--2-3 days
T cells--20-30 years
Why does apoptosis occur? What happens if there's a problem with apoptosis?
maintain level of all cells

Pertaining to apoptosis, why do some leukemias and lymphoma's result?
**Increase CSF receptor expression
Viral infection (ex. HTLV-1 and IL-2R) causes increased cytokine receptor expression
**Increased production of CSFs
What are the primary lymphoid organs?
Primary--thymus and bone marrow

Secondary--lymph node, spleen, blood, lymph system, gut associated lymphoid tissue (GALT)
What is GALT?
gut associated lymphoid tissue (GALT)

secondary lymphoid organ
Do B cells need to be at the site of infection?
No, they secrete antibodies that go to teh infection. Whereas T cells actually have to be on site
Where do cytokines and CSF's have to be in order to do their jobs?
in the bone marrow
Where does B of B cell come from?
From bursa of fabricius (chickens)

We can think of it as bone marrow
What is the order in which T cells are deteremined to be or not to be self reactive? What % of T cells will be destroyed?
First see if T cell recognizes MHC, then see if it binds to self Ag.

99% of T cells that go to the thymus are killed
Where are T cells found?
In the paracortex of the lymph node (LN)
What is found in the medulla of a lymph node?
plasma cells, secrete antibodies into the blood!
What is found in the cortex?
B cells, macrophages, FOLLICULAR dendritic cells
What is special about follicular dendritic cells?
It does NOT have MHC Class II,ie help T cells. INSTEAD they help B cells!!
Why are secondary follicles bigger?
Activated B cells, plasma cells ready to secrete antibody
What usually makes a primary follicle? A seondary follicle?
Inactivated B cells

A secondary follicle is a primary follicle and its Ag. ACTIVATED
What is inside the paracortex?
T cells (interact with Ag) need APC's too (dendridic cells and macrophates)
How do Ag's get into the lymph node?
via afferent lymph vessels AND dendritic cells bring in the Ag via afferent vessels too
How do effector cells or Abs leave the lymph node?
Via efferent lymph vessels OR the circulatory system
How many afferents and efferents are there?
Mulitple afferents, single efferent
What happens in a HEV?
High endothelial of post capillary venules. Bring lymphocytes to lymph node
What is a draining lymphnode?
lymph node closest to an area of infection
Where are B cells located in the spleen?
In the white pulp of the spleen

In the germinal center as mature plasma cells and in the marginal zone as immature B cells.
What are the two types of pulp in the spleen?
Red--removes old RBCs by macrophages

White--lymphoid area, immune response to BLOOD BORNE pathogens
What are PALS and where are they found?
PALS--peri-arteriolar lymphoid sheath. They surround splenic afteries and more importantly they are T CELL RICH!!
How do pathogens and lymphocytes enter the spleen?

different from lymph nodes!
What are some types of specialized lymphoid tissue?

mucosa, gut, bronchial, skin associated lymphoid tissue

areas of exposure to large #'s of microbes that have adapted and have specialized lymphoid tissue
What does MALT do?
mucosa associated lymph tissue has B cells producing IgA and intra-epithelial lymphocytes, ie GAMMA DELTA's found in gut and skin
What are two types of MALT?

Galt--tonsils, adenoids, appendix, peyers patches, mesenteric LN
Where are M cells found and what do tehy do?
found in intestines they have 2 functions. 1 grab ahold of bacteria and 2 release antibodies
Where are peyer's patches found?
Peyer's patches in intestine
Where will you find gamma delta lymphocytes? What are gamma delta's limited by?

What are "true" lymphcytes?
Gamma delta lymphocytes found in gut and skin. Limited in diversity.

"true" lymphocytes are alpha beta
What are dendritic cells in the skin called?
Langerhans cells
What types of cells are associated with specialized skin lymphoid tissue (SALT)
dendritic or langerhans cells. Tissue macrophages. gamma delta T cells
how can Ag-specific T and/or B cells find their Ag?
1. Draining LN – “meeting place” – keep Ag in area to interact with lymphocytes
Products/effector cells leave LN and go to site of Ag

2. Lymphocyte recirculation – movement from blood to lymphatics and back until contact with Ag
What are lymphocyte homing receptors? Where are they found?
Cell SURFACE glycoproteins on lymphocytes and other leukocytes that MEDIATE ADHESION to high endothelial venules (HEV).

Several different classes of lymphocyte homing receptors have been identified, and they appear to TARGET different surface molecules (ADDRESSINS) on HEV in different tissues.

The adhesion plays a crucial role in the TRAFFICKING OF LYMPHOCYTES
What is expression of homing receptors based on?
Variable expression based on stage of lymphocyte (maturity) and activation status
What is an addressin?
a molecule on the SURFACE of VASCULAR endothelial cells (HEV)that MEDIATES ATTACHMENT of specific leukocytes, particularly lymphocytes, to the endothelium, BINDING WITH THEIR HOMING RECEPTORS!!

They ATTRACT effectors (neutrophils etc) to the Lymph node
How do homing receptors and addressins work together?
Homing receptors are attracted to addressins. When they link they hold the cell stationary, so it damage can be repaired
How do effector cells, Abs, memory cells leave the lymph node?
Lymphatics → thoracic duct → blood → site of infection = fight infection
Where do memory cells in the skin go?
Some leave via lymphatic system and some stick around for future rxns
How often does the epidermis renew itself? Why is this helpful?
epidermis, primary nonspecific innate defense. Renewed 15-30 days. Microbes must attach to infect, this prevents attachment
What is secreted by the epidermis when damaged? What do these do?
IL-8 and TNF stimulate inflammation
What does the dermis have that inhibits bacterial growth?
sweat and sebaceous glands.

vascularized w/ hair follicles
What do langerhans cells do?
dendritic cells recognize Ag and recruit
What do normal folra do to inhibit microbes?
secrete restriction enzymes--chop up DNA and bacteriocins--inhibit other bacteria
What is an example of a bacteriocin?
colicin--inhibit other E coli's in the colon
Where are mucous membranes found?
Respiratory, Digestive, Genitourinary Tracts
What do mucous membranes secrete?
1. sIgA (secretory immunoglobulin) adaptive

2. Mucin

3. lysozyme
What does mucin do?
mucin--traps microbes. use mucocillary escalator to Kick out of respiratory tract by cough and sneezing. Smokers and cyctic fibrosis patients are impaired in this function
What does lysozyme do?
cleavage of bacterial cell wall (b1,4 linkage of peptidoglycan
Where is surfactant found? What does it do? What do pathogen binding proteins do?
Surfactant in respiratory tract. Doesn't allow pathogens to bind!!

pathogen binding protein is a type that connects the microbe to a macrophage.
What is an example of pathogen binding proteins? What do complement proteins do?
Ex. mannan binding protein. It can activate complement proteins, which lyse, stimulate inflammation, and opsonize in addition to pathogen binding protein properties!
What family do pathogen binding proteins belong to?
Name 4 Chemical mediators of innate defenses.
1. Stomach acid / digestive enzymes
2. Lysozyme – destruction of microbes
3. Interferon - antiviral
4. Complement cascade – antimicrobial
Cell lysis, opsonization, inflammation
Lowered stomach acid production can result in what type of infection?
What bacteria cause ulcers? How?
Heliobacter pylori--increases pH of a microenvironment so it can grow
What does interferon do?
makes cells resistant to viral infection by changing surface receptors. Inhibits viral replication and can even stimulate apoptosis b/c w/o a host the virus would die.
What are the more potent antiviral interferons? Why?
a and b IFN. produced in response to ds RNA (not found in mammals)

Increase TAP--Class 1 (CD8+)
What does gamma IFN do?
activates the immune system--produced by Th cells
What is CTL?
cytotoxic T lymphocyte, Tc, CD8+ = MHC I
What are the three things interferons can do?
1. induce resistance to viral replication

2 increase MHC Class 1 expression and Ag presentation in all cells

3. Activate NK cells to kill virus infected cells
What is phagocytosis activated by? What recognizes these?
Activated by:
molecules on microbes binding to toll-like receptors (TLRs)
Antibodies (Abs) coating microbe

Recognized by monocyte/macrophages and neutrophils
Describe following differences between Neutrophils and macrophages. Increase during inflammation? Found in what tissue? Forms pus? Forms granuloma? Lifespan?
neutrophils # increase in inflammation, found only in INFLAMMED tissue, forms pus rapidly, short lived--kamakazi!

Macrophages increase only slightly in inflammation b/c they're resident for most part, found in HEALTHY tissue too, forms granuloma, long lived b/c can survive phagocytosis.
How can microbes be recognized?
extravation of neutrophils, opsonization of microbe, CR4 and CD14 receptors bound to LPS, TLRs
What does CD14 bind to? CD3?
CD14 to LPS

CD3 a complement

Both bind to RECEPTOR on microbe
What does toll mean? How are thise used?

those used in innate defenses for recognition of microbes
--Have sequence similarity to toll a/k/a Pattern recognition receptors (PRRs)
What is TLR4?
Toll like receptor Important in binding LPS in humans
What kind of protein is a toll like receptor?
transmembrane signaling protein results in a cascade effect, brings in phagocytic cells
What do TLR's bind to?
esp ds RNA on microbes. Also, proteins, LPS, sugars, rna.

TLR bind to these items on a microbe.
Where are TLRs found?
ON cell membrane OR on cytoplasmic membranes (bind to DNA, RNA etc)
What happens when TLRs get stimulated?
inlfammatory response
What is a chemokine?
small cytokine causes inflammation
What does diapedesis mean?
movement thru a vessel wall
How do neutrophils get to the site of infection?
roll around in blood stream, lightly adhered to endothelial cells, bind tight when a flag is up, via diapedesis get thru vessel wall, into cell via migration
What are CRs? FcR?
complement receptors

FcR= binds to Fc region of Ab
How does complement induce phagocytosis?
complement binds to bacterium, then sends another complement out to bind to a receptor on a phagocyte, covalently bonds bacteria to phagocyte.
What do IL8 do? What do IL-1 and IL -12 do? IL6? IL-1, 6, TNF a? IL-12? TNF a?
IL8--chemokine cytokine (inflammatory)chemotactic for WBCs neutrophils esp.

IL-1, IL-12 – important in Th cell activation
Th1 (IL-12) versus Th2 activation

IL-6 – hematopoietic and B cell maturation

IL-1, IL-6, and TNFa – acute phase response

IL-12 – activate NK cells

TNFa – stimulates clotting (prevent movement of microbes into blood) and increases movement into lymph
Is it possible to have a cytokine that has an opposing function to another cytokine? What produces cytokine?

produced by lymphcytes and macrophages
Which cytokines are involved in acute phase response?

From where and what proteins are produced? What is their function?

Why won't they bind to human cells?
IL-6, TNF-a, and IL-1

From the liver
C-reactive protein and MBL (mannan-binding lectin) are produced.

Bind to structural features on sugars of microbe – allow for:
Alternative pathway of complement activation

Won't bind to human cells b/c structural features of microbe specific.

NOTE: CRP linked to cardiovascular risk
What causes septic shock?
Recognition of microbe by TLRs and other receptors

Overproduction of inflammatory cytokines (ex. TNF-a)

Systemic inflammatory reaction--can be fatal
What are the 4 major symptoms of inflammation?
rubor, palor, dolor, calor
When will you see a granuloma?
in chronic inflammation. TB and SCHISTOSOMA eggs
Which cytokines stimulate fever? How does it work?
IL-1, IL-6 and TNF-a

Interacts w/ hypothalamus--messes w/ thermostat, mm and fat cells. Increase temperature by mobilztion
What is the effect of increase in temperature?
Increases chemical reactions
Slows down microbe growth
What kind of cells do NK cells kill?
kill virally infected cells and tumor cells (altered self cells)
What is the function of NK cells?
To control the situation unitl the T cells can come in and kill.
What is the difference between an autoantigen, alloantigen, xenoantigen?
Autoantigen - a self Ag (autologous)
Alloantigen – an antigenic difference within a speices (allogeneic)
Xenoantigen – an antigenic difference between species (xenogeneic)
What are haptens?
Haptens – small molecules that are antigenic but NOT immunogenic
often need to be attached to a carrier to become immunogenic
What make for the most potent immunogens? Will carbohydrates stimulate a T cell? B cell?
Proteins followed by carbohydrates.

Carb will stimulate B cell--no T cell. Protein will stimulate both.
How is a "Good" Ag made? Must be presented otherwise no-go!
foreign, large size 100,000 daltons, aromatic AA (tyr, phe), D AA can't be processed.
What is the difference between TH1 and TH2?
TH1--T helpers activated
TH2--B cells activated
What acounts for differences in immune response among individuals?
BCR and TCR genetics, might lack one of them, etc.
In the example of leprocy an intracellular disease which response TH1 or TH2 is better?
TH1--activates T helper cells kill infections b/c intracellular response. If TH2 cells then activate B cells and response isn't effective.

Due to genetics
What can high or low doses of response do?
Low--not worth energy

Neither work well
Which is more immunogenic: aggregated or nonaggregated?
aggregated--get better response
Which is more effective: IV, SC, IM?
IM b/c will stay in system longer

In blood will be removed quickly
What type of protein will make the best antigenic?
more complex and multideterminant (multiple sites to be recognized)
What is a B and T epitope?
site of recognition on outside of Ag. B cells bind to B epitopes etc.
Which is more internal B or T epitope?
T more internal (tight)
B more external.

Makes sense because T cells recognize pathogens intracellularlly.
Are B cell epitopes sequential? T cells?

How large are the aa?

In order for a T cell to respond what must the Ag interact with?
B cells--can be sequential or not. 8-22aa

T cells are sequential
CD8+ 8-10aa
CD4+ 13-18aa

Ag must fit into TCR and MHC
What makes a polysaccharide more immunogenic?
bound to proteins or lipids.

more complex

allows for(ABO blood groups)
Do lipids and nucleic acids make good immunogens?
No. Lipids act as haptens when attached to proteins. Glycolipids can serve as immunogens.

Nucleic acids--if conjugated w/ protein then can be immunogenic. Anti-DNA Ab's aren't a good thing= lupis
What is an immunodominant epitope?
Immunodominant epitopes are capable of inducing a more pronounced immune response
What kind of responses do immunodominant epitopes create?
stimulate early (and often the best) responses
What happens if an immunodominant epitope is mutated? What disease is this associated with?
can weaken effect of immune response.

What do mitogens do? Are they Ag specific?
Activate t and B cells

Ex. LPS is a B cell mitogen

Concanavalin A (ConA) – T cell mitogen

NOT Ag specific
What type of response is generated from a T independent Ag?
B cells response--no memory cells
What type of response does a T dependent (TD) Ag require?
T cell help, i.e. cytokines. Generates immunological memory
Can TI 1 or 2 be Ag specific?
TI 2 can be Ag specific
What is required for a hapten to exhibit immunogenic response?
T cell help. Need a carrier bound by conjugate
Will differences like o,p,m spots on a ring be important to immune response?
How do cross reaction occur?
Non-related molecules can share epitopes and an immune response against one can “cross-react” with the other
How do hypersensitivities and autoimmunity occur?
If a “self-protein” becomes modified, one could react to the self-protein

Some microbe proteins may have same epitope as self proteins
How does a hapten-carrier produce Ag recognition?
Recognized by APC, engulfed, carrier peptides presented to Th cells.

When recognized, Th secretes cytokines to activate B cells (T cell help)

B cell recognizes hapten and secretes Abs
What are adjuvants? What does it do? What is this used for?
Adjuvants are compounds that when mixed with immunogens, makes them more immunogenic

creates a stronger immune response.

used in vaccines and expt studies
How do adjuvants work?
increase half-life of immunogens

increase production of inflammatory cytokines

improved presentation and costimulation of APCs to T cells
What is an example of an adjuvant?
an Ag in oil makes the Ag stay around longer= better immune rxn

Aluminum hydroxide or alumninum phosphate. (alum)

CFA (freunds complete adjuvant oil in water w/ killed mycobacteria) experimenal uses only

oil in water (Freunds incomplete adjuvant)

DC's Angitgen--Ag pulsed APC
Whta is Ag specificity of a b cell due to?
membrane bound Ig (part of the BCR complex)
How are B cells expanded?
clonal selection and proliferation allows for the expansion of B cells specific for one antigen
What is an activated B cell?
plasma cells that secretes soluble Abs

given B cell produces Ab with 1 Ag specificty
What are some functions of Ig?
pathogen neutralization, completment fixation, Ab dependent cellular cytotoxicity (ADCC), Opsonization, Inflammation
What is the difference between plasma and serum?
Plasma – fluid fraction Serum – clotted plasma
What can be used to determine multiple myelomas?

cancer of B cell producing monoclonal Ig--increase IgG
What are Rence Jones proteins?
Bence-Jones protein – produced in urine of patients with overproduction of light chains
What are 3 methods of enzymatic clevage of Ig?
How does Porter cleavage work?
use papain--yield FAB and Fc region

Nisonoff used pepsin--yild two F(ab)2 and Fc

Edelmann uses mercaptoethanol yields 2L and 2H chains
What links H chains together?
disulfide bonds at hinge region
What links L chains to H chains?
disulfide bonds @ CL region.
What are the 5 classes of heavy chains? What are the types of light chains?
5 classes of heavy chains (isotypes: IgG, IgM, IgA, IgE, and IgD…a/k/a g, m, a, e, and d)
2 types of light chains (k or l)
Where does an Ab bind?
N-terminal end where the VL and VH are joined
What binds to Ag?
What does Fc do?
biologic activity Complement and ADCC.
Is there inter or intra chain bonding? What type?
Yes, there's both. All by disulfide bonds
How many AA in an Ig domain?
100-110 aa long. has an intra-chain disulfide bond
Molecules with this fold are members of the what family?
Ig gene superfamily
Where is variability concentrated?

Which one makes the most contact with Ag?
Called Complementarity determining regions
a/k/a Hypervariable regions
(CDR): CDR1, CDR2, and CDR3

CDR3 makes most of the contact with Ag
What are framework regions?
less variable regions
What are subclasses of H chain isotypes due to?
differences in C region
What % of human Ig have kappa? lambda?
Which Igs have an extra domain? How do isotypes differ?
Ig m and E

Isotypes differ in glycosylation
Which forms of Ig are monomers? dimers? Trimers? tetramers? Pentamers?
G, D, E are monomers

A can be dimer, tri, tetramer

M is pentamer
Which Igs are high in plasma? tissue fluids? In secretions? In fetal passive immunity? on mast cells? In brain?
IgG and M are high in plasma

IgG high in tissue fluids

IgA high in secretions (dimers)

IgG fetus immunity

IgE on mast cells

None in brain unles damage to BBB
How many binding sites on IgM?
10 Ag binding sites
Does IgM ever exist as a monomer? When does IgM first appear? What is IgM good at? Why?
Only on surface of mature B cell

Appears first during a primary immune response.

best at C’ activation
best agglutinating Ab

because has so many binding sites!
When is IgG a dimer? How many binding sites does IgG have? How many subclasses?
NEVER--always a monomer.

2 Ag binding sites

4 subclasses
Where does IgG predominate? How long does IgG live?
blood and lymph
Longest half life of isotypes (23 days vs. 2-5 days)
When is IgG present?
appears in late primary and early secondary immune response
What does IgG do?
can activate C’
some subclasses cross the placenta
opsonin and mediates ADCC
What are Ig monomers good for?
What is IgA's function? When is it a monomer? dimer? tetramer?
Secretory Ig

monomer on surface of B cell
dimer (can be tetramer) when in secretions
What holds Igs together?
J chain
What component is present? What does it do?
Secretory component (SC) present
protective protein--protects against drying and enzymes
SC ~70,000 mw
MUCOPHILIC – attaches to epithelial and traps Ags in mucous where lysozyme can help degrade
What is the MAJOR Ig in the BODY?
Is IgD a monomer? What is it's function?
Yes monomer only. Unknown function--second receptor on B cell (after M cell). Coexpressed on surface of B cell. Maybe cooperates in initial B cell activation.
What is reagin? Where is it found?
reagin – binds to basophils and mast cells

Found in IgE.
What happens when IgE binds Ag? What does IgE protect against?
causes degranulation of mast cell = allergic reaction
a/k/a Type I hypersensitivity (Immediate type hypersensitivity)
protection against parasitic worms – causes acute inflammatory reaction
Why is IgE lowest in serum?
cleared from serum when binding to mast cells
short half-life in blood but long on surface of mast cell
What must occur for IgE to work?
Must bind allergin in between two IgEs
what is the difference between an isotype, allotype, and idiotype Ig?
Isotypes – SELF 5 major classes in humans (A-E)
determined by C-regions of the H-chain
some describe light chain isotypes as well (k and l)

Allotypes – allelic forms of the same protein that can vary within a SPECIES usually 1-2 a.a. changes (ex. same Ab, different AA sequences)

Idiotypes – due to the variable region of the Ig (differences in a.a. sequences due to variable binding to Ags)
essentially a clonal marker for a given B cell. CDRs
How can we produce millions of different Abs with limited genes?
Ig gene rearrangement
How was Ab gene arrangement discovered?
myeloma cancerous B cells producing too much Ab--IgG. Howed segments differed in size from germline and mature cells
What are the gene segments of a Heavy Chain? Light chain?
Heavy Chain:
V, D, J and C region genes

Light Chain
V, J, and C region genes
How is selection of genes performed? When does it occur?
selection is random and occurs BEFORE Ag stimulation
What can happen AFTER Ag stimulation?
Class switching. Can change isotype--ex. IgA to IgG etc
How many alleles can be expressed at once?
One at a time. Have 2
During the process of Ig gene rearrangement, if the first allele is successful, what happens?

What happens if the first allele is non-productive?
then the process stops

if the first allele is non-productive, then the other allele will be re-arranged
Is gene rearrangement controlled or uncontrolled?
controlled. occurs in specific order
What order do genes rearrange in?
H chain first, then kappa light, then lambda light chains
What is the progression of a B cell?
hemopoietic stem cell to lymphoid cell to proB cell (heavy completed) to preB (kappa light complete) to immature B cell (lambda complete) to Mature B cell (changes in RNA processing)
From a mature B cell how does development progress?
mature to memory cell OR activated by Ag, then differentiates to plasma cell then can switch isotypes or classes.
What does the J gene join?
join variable region with constant region
How to select ONE V region and not two or more?
flanking the V region DNA are recombination signal sequences (RSS)

hepatmer, 12 or 23 bp intervening sequence, then an AT-rich nonamer sequence

12/23 bp rule – a 12 bp sequence can join with a 23 bp sequence
How are the genes bound?
D and J join first, then V joins D
What is a RAG?
recombination activating genes
What do RAGs do?
RAG enzymes bring together
the 12/23 sequences.
How are functional and non-functional DNA sequences made? Note: non-functional is circular
V(D)J recombinase – the complex of enzymes important in recognizing and excising the intervening sequences (looping out)
What are types of recombinases that are expressed only in B and T cells? What do they do?
RAG1 and RAG2 – recombinase activating genes
expressed only in B and T cells
“recognize” and bring together the RSS
other components of VDJ recombinase are expressed in other cells (helpful in DNA repair)
DNA ligase, DNA-dependent protein kinase, etc.
What does Tdt do?
Terminal deoxynucleotidyl transferase (Tdt)
adds back nucleotides in the “joining” region
Non-germline bases (= N nucleotides)
Why are IgM and IgD expressed first?
they are the constant region sequences closest to the VDJ sequences.
Do light chains have D regions?
How many heavy and light chains will a B cell express?

How many alleles do humans have for IgH? IgL?
One of each.

four for IgL and 2 for IgH

2 for kappa and 2 for lambda
Can express
maternal/paternal; or
How many heavy chain options are there for V, D, andJ?
65 VH, 27 DH, 6 JH
What happened in the following ex: VH32 with DH15 with JH2 OR VH32 with DH8 with JH2 ?
Combinatorial V-(D)-J joining--Generation of Diversity - Ig
Does the Ag bind to the heavy chain or light chain?

either one or combination of the two

binds to variable region of both.
Are the VDJ or VJ regions bound in a precise way? What does this lead to? (2 things)
Junctional flexibilty. Not precise. Increases diversity. Can also produce non-productive rearrangements.
What happens in P region nucleotide addition (P addition)?
addition or deletion of bases by the repair enzymes
happens in the joining together of the two cut sequences
essentially simultaneous with junctional flexibility
What happens in N-region nucleotide addition (N-addition)
addition of bases by Tdt (only in H chain)
can add up to 15 bases
completely random bases are added (not coded for)
What happens in somatic hypermutation?
mutation that occurs in a mature B cell (after Ig gene rearrangement)

mutation rate = ~10-3/bp/generation (hypermutation)

“normal” mutation rate = ~10-8/bp/generation
What estimate has been given for # of possible Abs when junctional flexibility, P-addition, N-addition, and
somatic hypermutation are added to genetic variation?
10 to the 16th Ab
Where is there a higher area of mutation?
In VDJ region
Where are mutations in heavy chains? light chains? Why?
Mutation in CDR3—hypervariable region. In heavy chain

Light chain in CDR1

Have most of interaction with the Ag—Variable region
What is affinity maturation?
Ag specific B cells will then mutate and potentially generate higher and higher affinities