Humoral Immunity I (Lecture 3)

Question 1

Basic Antibody Structure

Following injection with antigen, what was observed
on electrophoresis was a massive increase in the size of globulin peak of
serum proteins, specifically ____-globulins (the last peak), because
most ____ are gamma globulins

Answer 1

gamma

antibodies

Question 2

Basic Antibody Structure

• Antibodies are ____ composed of ____ peptide chains:

• two identical ____ (mw ~ 25,000) chain proteins and
• two identical ____ (mw ~ 50,000) chain proteins.

identical here means they have the same ____

Answer 2

glycoproteins
four
light
heavy

AA sequence

Question 3

Basic Antibody Structure

Multiple Myeloma: an experiment of nature

• neoplasia of ____ cells that accumulate in the bone marrow
• accumulation of protein in ____ and ____

all tumor cells are identical because they derive from one cell; large number of plasma cells are producing same type of ____ molecule

ran electrophoretic profiles of body fluids that could easily get their hands on

in MM patients; increase in the ____ serum peak and small peak in the ____ (normally nothing present in urine); accumulation of proteins in blood/urine is due to the plasma cells and the proteins represent the component chains of antibody molecules

peak found in urine = bence jones protein = free antibody light chains

Answer 3

plasma
blood
urine

antibody

gamma-globulin
urine

Question 4

Basic Antibody Structure

There are certain positions on the antibodies that have a lot
of variability in ____.

Answer 4

AA

Question 5

Basic Antibody Structure

look at amino terminal end of light-chain protein; you will find areas where AA is highly ____ (red) and other areas where it is low (yellow); localized to the ____ end of amino acids

similar research and pattern for heavy chain proteins

majority of variability is localized to the ____ ends of these proteins (carboxy ends had very low variability)

Answer 5

variable
amino terminal

amino terminal

Question 6

Basic Antibody Structure

• The sequence of the ~ 110 amino acids at the amino terminal end of light and heavy chain proteins varies ____ between antibody molecules; they are referred to as the ____ regions.
• The remaining 110 and 330 amino acids of light and heavy chain proteins, respectively, exhibit much less____; thus, they are referred to as the ____ regions.

Answer 6

significantly
variable

variability
constant

Question 7

Basic Antibody Structure
• Although the amino acid sequences of the constant regions of all light chain and all heavy chain proteins are very similar, they are not ____.

• On the basis of similarity in the amino acid sequences of their constant regions there are ____ groups of light chain proteins (κ and λ, either 2 kappa or 2 lambda, never ____ the two groups together) and ____ groups of heavy chain proteins (α, δ, ε, γ and μ).

Answer 7

identical
two
mixes
five

Question 8

Human Immunoglobulin Classes

each of different classes exhibits the four chain prototypic structure

IgG > contain ____ HC, or ____ LC

IgA > contain ____ HC, or ____ LC

and so on (depending upon the letter of the heavy chain protein and Ig)

____ bonds formed by cysteine that exist within the interacting chains; disulfide that holds two chains together = referred to as ____, or between two different chains = ____ (holds LC and HC to one another) > form the globular domains that are characteristic of the 3D structure of these proteins

IgG, IgE and IgD mimic the prototypic structrue = ____forms of Ab molecules (composed of one four chains structure)

IgA = found as a ____ or a ____ form (secretatory; two IgA monomeric molecules held together by ____ chain and ____ component)

secretory IgA is the ____ form of Ab found in ____; important mediator of mucosal surfaces

IgM is only found in the structure of an IgM ____; similar to the IgA dimer, it is held together by the ____ protein

____ has few carbs; ____ and ____ has more

Answer 8

gamma
kappa/lambda

alpha
kappa/lambda

disulfide
interchain disulfide
intrachain disulfide

monomeric

monomer
dimeric
J
secretory

predominant
bodily secretions

pentamer
J chain

IgG
IgA
IgE

Question 9

Antibody Structure and Function

IgG, treated with papain, will cleave right above the disulfide bonds that hold heavy chain proteins
together. You get three cleavage products: ____ fragment, and two identical ____.

Fc fragment contains the
____ terminal half of the two heavy chain proteins. Fab contains entire ____ and ____
half of heavy chain.

They repeated the experiment with a different enzyme, pepsin ,which cleaves below the disulfide bonds that hold the heavy chains together, and they got ____, which is the two identical Fab held together by disulfide bond, and chewed up Fc portion.

Then they did experiments involving equilibrium dialysis, where they put antigens on one side of a dialysis
bag and cleavage fragment on the other, to find out which fragment interacts with antigen.

What they found was with papain derived products it was Fab, and with pepsin derived products it
was Fab2. It really just confirmed that it was the ____ portion of the antibody molecule responsible for
antigen binding.

The constant region of the heavy chain proteins made up of the Fc fragments are responsible for
determining the ____ function of the antibody molecule. Ex. Ig classes have different functions, based
on the AA sequence of ____ constant region.

Answer 9

Fc
Fab

carboxy
light chain
amino terminal

Fab2

amino

effector

heavy chain

Question 10

Antigen-Antibody Interactions

what determines the specificity in the binding site? > comes down to the ____ sequence (based on the ____ structure, which is made up of the primary AA sequence)

all interactions involve ____ bonds

Answer 10

AA
3D
non-covalent

Question 11

Antigen-Antibody Interactions

Antigens binding site has set ____ structure. Things that have shape that fit the binding site are capable of fitting, but those with DETERMINITES that maximally engage ____ regions are going to have the highest affinity interactions. High affinity interactions are important for mediating biologic type responses.

Antibodies will bind a number of different epitopes, but only a limited amount end in ____ reactions.

Answer 11

3D
hyper-variable
biologically significant

Question 12

Antigen-Antibody Interactions

for van der waals, the strength was dependent upon the ____ between the two molecules > the closer two molecules get to one another, the stronger the interaction becomes

interactions are ____, ____ in nature, and are dependent on how ____ the two molecules get to one another

Answer 12

distance
reversible
non-covalent
close

Question 13

Antigen-Antibody Interactions

• Antigen-antibody binding represents interactions between two structures with ____ three- dimensional shapes.
• The interactions are non-covalent and reversible in nature; thus, they are operate over short distances necessitating that the structures be extremely ____ to one another.

Answer 13

complementary

close

Question 14

Antigen-Antibody Interactions

binding region at ____ end;

biologic effector is due to ____ on the ____ regions

Answer 14

amino terminal
heavy chain
constant

Question 15

Antibody Structure and Function

Function of Carbohydrate Side Groups

1. Increase ____ of antibodies.
2. Inhibit ____.
3. Enhance ____ activity of Fc domains.

____ of the constant region of the heavy chain protein determines which Ig molecule is which

____ groups on heavy and light chain proteins help inhibit degradation of the Ig molecules

**he will ask about this!

Answer 15

solubility
degradation
functional
AA sequence
glycosylated

Question 16

Human Immunoglobulins Classes

structural characteristics of the diff molecules

IgG - ____ molecule (4 chain)
IgE, IgD - also found in monomeric form
can bind to ____ epitopes

IgA - either found as a ____ or a ____ form of IgA (secretory form)
can bind to ____ epitopes

IgM - secreted form always exists as an IgM pentamer (5 identical monomers help together by a J chain); this molecule can bind to ____ identical epitopes simultaneously

Answer 16

monomeric
2

monomeric (2)
dimeric
4

10

Question 17

Properties of Human Immunoglobulins

different classes of Ab have different functions

transport across placenta - only ____ molecules can be transported across the placenta; has to do with the structure with the ____ chain constant regions (____ heavy chains)

transport across epithelia - ____ are transported at a very high rate (has to do with the structure of the heavy chain of these molecules)

IgG is the predominant class of Ab found in ____; ____ is found at very low levels within serum

Answer 17

IgG
heavy
gamma

IgA dimers

serum
IgE

Question 18

Physical States of Antibodies
Normally, antibodies may be found in one
of three physical states:

1. Integrated into the \_\_\_\_ membrane of
a \_\_\_\_ acting as an antigen receptor.
2. Associated with \_\_\_\_ on the surface
of numerous cell types.
3. In a \_\_\_\_ form, dispersed in bodily fluids
including serum and saliva.

Answer 18

plasma cell
B cell
Fc receptors
soluble

Question 19

Antibody as an Antigen Receptor

the thin line that is found adjacent to the C-terminal end of the heavy chain proteins = this is a ____ domain and a ____ domain; the Ab is ____ inserted into the membrane

the cytoplasmic domain > the Ab can transduce a signal into the cell (the ____ of the B cell that will recognize what to interact with)

interacts with ____ and ____ > co-stimulatory molecules that enhances the ability of the Ab once it binds to the antigen, to transmit a signal to the inside of the B cell

the only types of cells that have Ab in this configuration are ____!

Answer 19

transmembrane
cytoplasmic

“eyes”

IgAlpha
IgBeta

B cells

Question 20

Antibody Associated with Fc Receptors on Cell Surfaces

1. Second possibility:
   A. Antibody has been secreted by ____ cell, interacts with surface of other types of cells,
   because those cells express FC receptor. On left hand pic, green lines represent Fc
   Receptors.
   B. For now, just know that Fc regions exist.
2. They interact with ____ regions of heavy chain proteins
   A. Example: FC-gamma only interact with IgG. There is ____ in this interaction.
3. In this configugrion, antibody is not physically inserted into cell membrane, but FC receptors themselves do have transmembrane and cyoptlasmic domains. This tells us that these
   molecules are capable of ____ signals inside of cells. once the antibody has bound antigen that they are specific for.

But if it has NOT engaged antigen, interaction is inconsequential, does not cause cell to do anything.
When the antibody engages the antigen it is specific for, ____ event occurs.
This can result in ____ of cell or maybe ____ of activity of cell depending on the type of FC receptor

Answer 20

plasma
constant
specifcity
transducing

signal transduction
activation
inactivation

Question 21

Physical States of Antibodies

____ inserted into the cell membrane of a ____

____ associated with the cell membrane of a ____ of cell types

Answer 21

physically
B cell

“indirectly”
variety

Question 22

Soluble Antibody Secreted by Plasma Cells

no ____ domains on secreted Ab

these molecules ultimately bind to ____ on different cell types

Answer 22

transmembrane/cytoplasmic

Fc receptors

Question 23

Physical States of Antibodies

____ on B cells

associated with ____ on cell membranes of ____ types of cells

____ form secreted by ____ cells

Answer 23

antigen receptors
FcRs
various
soluble
plasma

Question 24

Physical States of Antibodies

predominant type of Ab found in secretions: ____

outer aspect of tube = ____
inner aspect of tube = ____

immune reactions that involved Ab, that take place in connective tissues underlying skin = ____

within the connective tissue, on the inside of our bodies = ____

on the surfaces of mucosal surfaces (GI, utrinary, intestinal) = secreted form of ____

____ involved anywhere, in serum in secretions (found in ____ levels bc it’s not very potent)

placenta and FETUS > during gestation has mainly ____ (transport of maternal IgG molecules across the placenta into fetal irculation) > provides a source of humoral immunity right at time of birth (____ months after birth, then newborn makes it’s own Ab)

white areas > ____, ____, part of ____, surrounding the ____ > referred to immunologically privileged sites > you don’t see immune reactions taking place in this areas (don’t want inflammation in the brain, amnion, or eyes)

Answer 24

IgA

IgE
IgE

IgE

IgG

IgA (dimer)

IgM
high

IgG
3-4

brain
CNS
eye
fetus (amnion)

Question 25

Physical States of Antibodies

adaptive > artifical
artificial - induced by immunizations (active), or by passive (snake bites, etc.)

adaptive > natural > ____
maternal transfer of Ab (IgG); either by crossing ____ in utero, or via ____ (IgG in very high levels)

Answer 25

passive

passive
placenta
breast feeding

Question 26

Properties of Human Ig Classes

LOOK OVER THIS TABLE - JULES LECTURE
B cells can have antibody on their cell surfaces via two mechanisms: they can have antibody inserted into ____ where they serve as antigen receptors. OR they can have antibody bound to ____ on the surfaces of B cells.

See that some classes of antibody have a large number of biologic functions (____) and limited (____). at this point in time: only know important function of IgD is to act as ____ early in the differentiation of B cells.

Answer 26

plasma membrane
Fc receptors
IgE
IgD
B cell antigen receptor

Question 27

Effector Functions of Antibodies

To show that the different subclasses of IgG manifest different biologic functions.
There are FC receptors for the surfaces of ____ across all classes.

Macrophages are only ____ and ____.
Percentage differs, but IgG 1 is the ____ class. Different classes of IgG do ____ fixation. IgG1 and IgG3 are very good at it, ____ is very bad.

Answer 27

neutrophils
IgG1
IgG3
predominant
complement
IgG4

Question 28

Effector Functions of Antibodies

• Simple antigen-antibody interactions
• Interactions with ____ (neutrophils)
• Interactions with ____ (complement)

Answer 28

accessory cells

accessory molecules

Question 29

Neutralization of Viruses

The first event in viral infection is binding of the virus to the surface of the target cell via a receptor-ligand interaction. For influenza virus this involves viral binding of viral hemagglutinin to cell surface molecules containing ____.

depending on the type of virus, they will have molecules on the surface that allow them to ____ infect one cell type over another (HIV > CD4 on immune cells, etc.)

____ > target specifictiy of a virus, is dictated by molecules on cell surface that arre involved in cell binding

____ on the surface of virus can act as antigens > the 3D conformation of the glycoprotein provides the immune system multiple ways of recognizing it via distinct epitopes; immune system reacts against this molecule

Answer 29

sialic acid
differentially

metropism

glycoproteins

Question 30

Neutralization of Viruses

The “classic” example of viral neutralization is ____ inhibition of viral binding to a target cell. However, antibody specific for appropriate viral molecules can interfere with virtually any ____ of the viral life cycle and thus effectively neutralize the virus.

once binding to target cell > # of other events that takes place > antibody has the potential to interfere with a number of different ____ (even within the cell), doesn’t only prevent antigen from binding to the target cell

Answer 30

antibody-mediated
phase

processes

Question 31

Inhibition of Bacterial Adhesion

first thing that must occur, microbe has to attach to an individual cell or tissue

the way they colonize our bodies, via interaction of ____ and ____ receptor on the host cell/tissue

tip is a protein that has a ____ 3D structure, but only that Ab that bind to specific portion on the tip that can prevent the bacteria from binding the receptor

if virus has already infected, preventing further binding will not even help; will need antibodies against other ____ (only stops the ____ portion of a pathogens lifestyle)

this reaction is not ____ to any class of Ab; ____ region of light/heavy chain have to do with the specificity of the binding (any class of Ig can be binding, as long as the variable region recognizes the epitope)

Answer 31

adhesive tip
pilus

common

steps
extracellular

unique
variable

Question 32

Neutralization of Toxins (and Venoms)

toxin is the yellow pentagon and red circle; toxins have ____ domains associated with them; the yellow part is responsible for target cell binding, and the red part is responsible for mediating some type of biologic effector function; in order for the toxin to mediate, it must get inside the target cell

internalized via receptor-mediated ____ > carried into the cells and carries out its biologic activity (red)

produce Ab against ____ domain of toxin > capable of neutralizing activity of that toxin

Can be mediated by ____, ____

Answer 32

functional
endocytosis

cell-binding
IgA
IgM

Question 33

Bacterial Toxins

A ____ is a poisonous substance produced by living cells or organisms.

where this becomes relevant is number of different bacterial cells produce toxins (tetanus), and the bioactive portion gets into neurons, and inhibits neuron activation. results in chronic muscle ____.

Botulism: typically an ____ organism. Can also lead to ____. presence of toxins is not limited to one species.

Answer 33

toxin
contraction
anaerobic
paralysis

Question 34

Immunotherapy: Antibody-Mediated Inhibition of Inflammatory Cytokines

rheumatoid arthritis > breakdown of synovial structures and cartilage > dependent upon the production of ____ by macrophages (____)

macrophage release ____: inhibit chondrocytes, activate osteoclasts, and interferes with normal function of synovial fibroblasts (produce synovial fluid) > ultimately, joint damage

produce Ab directed against ____ mediators, so they can’t bind cells that they’re responsible for affecting, so we can ameliorate symptoms of RA

____ > Ab binds directly to TNFalpha, and prevents its binding to the receptor > should down-modulate the level of inflammation that occurs in these individuals

Answer 34

inflammatory mediators
TNF-alpha

TNF-alpha
pro-inflammatory

infliximab/remicade

Question 35

Mucosal Immunity

unique types of ____ cells that are activated in the context of infections

don’t memorize the whole table; but they are distinct types of tissues anatomically (relative to skin)

Answer 35

T

Question 36

Secretory IgA

mucosal immunity > ____ (this picture)

two monomers held together by a ____, in conjunction with another protein (____)

this is what it looks like by the ____ lineage (the end product)

Answer 36

secretory IgA
J chain
secretory component

B-cell

Question 37

Secretory IgA

imagine this is taking place in salivary glands

outer cell layer is one (maybe two) cell layers thick > plasma cells within the tissue secrete ____ > at mucosal sites they preferentially produce ____ (due to the ____ cells mentioned earlier; play important role in telling plasma cells what class of Ab they should produce)

selectively transport IgA dimers from connective tissue into the lumen, which ultimately can be excreted into oral cavity

the j-chain protein (holds the monomers) binds to a molecule on ____ side of epithelial cells > the poly-Ig receptor; the specificity of the receptor is for the ____ protein (NOT TH E MOLECULE ITSELF); hypothetically, if producing IgM pentamers, it technically can also bind the receptor!

dimers bind the receptor, and the ____ complex (w/ receptor) is internalized, and the vesicles transported across the cell, fuse with luminal surface, and the contents are dumped into the lumen

a portion of the ____ receptor remains in contact with the dimer when excreted into the lumen; the four orange squares represent the ____ (which is derived from the poly-Ig receptor)

secretory component ____ the structure of the IgA dimer once it enters the lumen of a mucosal structure

Answer 37

IgA
secretory IgA
specialized T

abluminal
J chain

whole

poly-Ig
secretory component
stabilizes

Question 38

Secretory IgA

induction of T cell response

T cells that are produced in mucosal surfaces, produce soluble molecules that bind to receptors on surface of ____ that you need to produce IgA molecules

Answer 38

plasma cells

Question 39

Secretory IgA

REWATCH THIS ONE NOW

Answer 39

YES

Question 40

Once toxin is ____ cell, IgA cannot do anything further

Parasites and helminths use ____ as route of entry, secretory IgA acts on these.

Answer 40

inside

gut