Antibodies Flashcards
Also known as immunoglobulins
antibodies
End product of antigen stimulation and differentiation of B cells
antibodies
Glycoproteins found in the serum portion of the blood
immunoglobulins
Immunoglobulins constitute approximately ___ of plasma proteins in healthy individuals
20%
Immunoglobulins are composed of ____ polypeptide
86-98%
Immunoglobulins are composed of ____ carbohydrate
2-14%
Play an essential role in antigen recognition and in biological activities related to the immune response such as opsonization and complement activation
immunoglobulins
The immunoglobulins are divided into _____ on the basis of a part of the molecule called the heavy chain
five major classes
5 major classes of Immunoglobulins
IgG
IgM
IgA
IgD
IgE
gamma immunoglobulin
IgG
mu immunoglobulin
IgM
alpha immunoglobulin
IgA
delta immunoglobulin
IgD
epsilon immunoglobulin
IgE
Tetrapeptide, elucidated by _____ and ______
Gerald Edelman and Rodney Porter
Consists of two large chains called heavy or H chains and two smaller chains called light or L chains
immunoglobulins
Each chain has a single variable region (unique to each specific antibody) and one or more constant regions
immunoglobulins
Immunoglobulin chains are held together by ______ and _____
non-covalent forces and disulfide interchain bridges
Cleaved IgG into 3 pieces
papain digestion
“fragment crystallizable”
Fc fragment
Spontaneously crystallized at 4 ̊C
fragment crystallizable
Has no antigen binding ability
fragment crystallizable
Important in the effector functions of Ig molecules (opsonization and complement fixation)
fragment crystallizable
“fragment antigen binding”
2 identical Fab fragments
Have antigen-binding capacity
fragment antigen binding
fragment antigen binding consists of ______ and _____ held together by disulfide bonding
one L chain and one-half of an H chain
Cleaved IgG at the carboxylic-terminal side of the interchain double bonds
pepsin digestion
F(ab’)2 and Fc (similar to Fc except that it disintegrated into several smaller pieces)
pepsin digestion
2 types of light chains:
kappa chains
lambda chains
each light chains contains between ______ amino acids
200-220
2 light chains have the same sequence from ____ onwards (the amino terminus is position number 1)
111
the region with the same amino acid sequence
constant region
amino-terminal end
variable region
60% of L chains are ______ because they are coded for first in DNA transcription of genes coding for antibody molecules
kappa chains
The difference lies in the amino acid substitutions at a few locations along the chain
light chains
No functional differences between the two types
light chains
Both are found in all five classes of immunoglobulins, but only one type is present in a given molecule
light chains
With variable and constant regions
heavy chain
constant region - location of the first approx. ___ amino acids at the amino-terminal end
110
Constant region - location of the remaining amino acids, can be divided into 3 or 4 constant regions with very similar sequences: ____, ____, and ____
CH1, CH2, and CH3
HEAVY CHAIN
Unique to each class and give each immunoglobulin type its name:
IgG has an γ H chain, IgM a μ chain, IgA
an α chain, IgD a δ chain, and IgE an ε chain
___ has an γ H chain
IgG
___ has a μ chain
IgM
___ has an α chain
IgA
___ has a δ chain
IgD
___ an ε chain
IgE
A unique amino acid sequence that is common to all
immunoglobulin molecules of a given class in a given
species, determined by the heavy-chain constant region
isotype
There are five antibody isotypes that each have a unique heavy-chain constant region:
IgM, IgD, IgG, IgE, and IgA
Minor variations in isotype
allotypes
_____ occur in the four IgG subclasses, in one IgA subclass, and in the κ L chain
allotypes
Variable portions of each chain that are unique to a specific antibody molecule
idiotype
Amino-terminal ends of both L and H chains, serve as the antigen recognition unit
idiotype
The segment of H chain located between the CH1 and CH2 regions
hinge region
Has a high content of proline and hydrophobic residues
hinge region
Gamma, delta, and alpha all have a hinge region, but
___ and ___ do not
mu and epsilon chains
HINGE REGION
All types of immunoglobulins contain a carbohydrate
portion, which is localized between the ________
CH2 domains of the two H chains
Allows for flexibility and assists in effector functions
including initiations of the complement cascade and
binding to cells with specific receptors for the Fc portion of the molecule; lets the two antigen- binding sites operate independently and engage in an angular motion relative to each other and to the FC stem
proline
Increases the solubility of immunoglobulin
carbohydrates
Provides protection against degradation
carbohydrates
Enhances functional activity of the FC domains
carbohydrates
Predominant immunoglobulin in humans
IgG
70 – 75% of total serum immunoglobulins
IgG
half-life of IgG
23 days
IgG has __ major subclasses
4
IgG1
66%
IgG2
23%
IgG3
7%
IgG4
4%
IgG:
Subclasses differ mainly in the number and position of the disulfide bridges between the ______
γ chains
IgG:
All subclasses have the ability to cross the placenta
except ____
IgG2
IgG:
Variability in the hinge region affects the ability to reach for antigen and the ability to initiate important biological functions such as ________
complement activation
Most efficient IgG
IgG3
mediators of complement activation
IgG1, IgG2, IgG4
Provides immunity for the newborn
IgG
___ is the only antibody that can cross the placenta
IgG
Fixing complement
IgG
Coating antigen for enhanced phagocytosis (opsonization)
IgG
Neutralizing toxins and viruses
IgG
Participating in agglutination and precipitation reactions
IgG
Known as a macroglobulin because it has a sedimentation rate of 19 S, which represents a molecular weight of approximately 900,000
IgM
molecular weight of IgM
approximately 900,000
half-life of IgM
about 6 days
5% and 10% of all serum immunoglobulins
IgM
Assumes a starlike pattern with 10 functional binding sites
IgM
Found mainly in the intravascular pool because of its large size
IgM
Cannot cross the placenta
IgM
Known as the primary response antibody
IgM
It is the first to appear after antigenic stimulation and the first to appear in the maturing infant
IgM
Synthesized only as long as antigen remains present
because there are no memory cells for ____
IgM
Can be used to diagnose an acute infection, as its presence indicates a primary exposure to antigen
IgM
2 forms of IgM
pentamer
monomer
Found in serum, held by a J or joining chain which serve as linkage points for disulfide bonds between 2 adjacent monomers
pentamer
Facilitates secretion as mucosal surfaces
pentamer
Present on the surface of B cells
monomer
functions of IgM
(COAT)
Complement fixation
Agglutination
Opsonization
Toxin neutralization
Represents 10% to 15% of all circulating immunoglobulin
IgA
IgA appears as a monomer with a molecular weight of approximately _____
160,000
IgA has a sedimentation coefficient of ___
7 S
2 sub-classes of IgA:
IgA1
IgA2
IgA Has a ______ that protects it from enzymatic digestion while it patrols mucosal surfaces
secretory component (SC)
Aggregation of immune complexes may trigger the
alternate complement pathway
IgA
predominant form in secretions at mucosal
surfaces
IgA2
mainly found in serum
IgA1
anti-inflammatory agent
Serum IgA
Downregulates IgG-mediated phagocytosis, chemotaxis, bactericidal activity, and cytokine release
IgA
patrol mucosal surfaces and act as a first line of defense
Secretory IgA
Plays an important role in neutralizing toxins produced by microorganisms and helps to prevent bacterial and viral adherence to mucosal surfaces
Secretory IgA
In breastmilk, it maintains the health of newborns by passively transferring antibodies and greatly decreasing infant death from both respiratory and gastrointestinal infections
Secretory IgA
Representing less than 0.001% of total immunoglobulins
IgD
half-life of IgD
1 to 3 days
Found on the surface of immunocompetent but unstimulated B lymphocytes
IgD
The second type of immunoglobulin to appear (IgM
being the first) and it may play a role in B-cell activation
IgD
Best known for its very low concentration in serum (0.0005% of total serum immunoglobulins)
IgE
Has the ability to activate mast cells and basophils
IgE
The most heat-labile of all immunoglobulins
IgE
IgE:
Heating to ___ for between _____ and ____ results in conformational changes and loss of ability to bind to target cells
56°
30 minutes and 3 hours
Shortly after synthesis it attaches to basophils, Langerhans cells, eosinophils, and tissue mast cells
IgE
Induces type 1 immediate hypersensitivity or allergic reaction and mediates phagocytosis of parasites
IgE
(T/F)
A primary immune response occurs when the body’s immune response encounters an antigen for the first time
true
The primary response to an antigen takes _____ before antibody can be detected
5 to 7 days
The primary response consists of approximately equal amounts of ___ and ___
IgM and IgG
(T/F)
During this immune response, the body learns to
recognize the antigen, produce antibodies against the antigen, and induce a long-term memory response against the antigen.
true
Memory induction is enabled by the production of
___________
immune memory lymphocytes
The response induced involved the activation of _______
naive B-cells and naive T-cells
The response lasts about _____ to resolve
14 days
Stages of Primary Antibody Response:
(LEPD)
Lag phase
Exponential phase
Plateau phase
Decline phase
It is also known as the latent phase
lag phase
It is the phase of the initial exposure to the antigen
lag phase
This leads to the activation of naive B-cells that produce antibodies to counter the antigen
lag phase
This phase takes a week, activating the specialized B
and T cells that come into contact with the antigen
lag phase
This is the phase of a rapid increase in antibody
production by the differentiated plasma cells (plasma cells)
exponential phase
The increase in antibody production is because of the large number of plasma cells.
exponential phase
This is a steady phase where the antibody level remains constant to maintain the levels of antibody replenishing and production. This means that the antibodies that get used up equal the antibodies that are produced.
plateau phase
This phase involves a decrease in antibody levels due
to the decline in plasma cell numbers which are dying out of exhaustion of antibody production. During this phase, there are no new plasma cells being produced because the antigen or immunogen has been eliminated from the system.
decline phase
Also known as the amnestic immune response
Secondary (Anamnestic) Antibody Response
(T/F)
The secondary response to antigen occurs in a shorter time
true
The amount of IgM is similar to that of the primary
response, whereas IgG may be up to one hundred times greater than that of the primary response
Secondary (Anamnestic) Antibody Response
This is the subsequent immune response after the primary immune response
Secondary (Anamnestic) Antibody Response
The response that occurs the second or third or fourth time the body encounters the same antigen it
encountered during the primary response
Secondary (Anamnestic) Antibody Response
(T/F)
Immediately after the same antigen is encountered the memory lymphocytes induce the production of
antibodies.
true
This response has a very short sharp lag phase which
means that both lag and exponential phases take place at ago. The antibody production levels increase rapidly within a short period, normally within a few days.
Secondary (Anamnestic) Antibody Response
(T/F)
This is because of the antigen-specific memory T and B-cells produced during the primary response.
true
(T/F)
Because of the rapidity of the secondary response, the antigen gets eliminated as soon as it encounters the memory cells and before it can cause disease.
true
The antibodies produced during this response remain circulating freely to ensure complete elimination of the antigen.
Secondary (Anamnestic) Antibody Response
Very specific antibody rising from a single plasma cell that has been cloned or duplicated
MONOCLONAL ANTIBODY
MONOCLONAL ANTIBODY is discovered by ____ and ____
Georges Kohler and Cesar Milstein
Monoclonal antibodies are made when a cancerous cell or myeloma is fused with an antibody-producing cell to form a ______
hybridoma
cancerous plasma cells
Myeloma cells
HOW HYBRIDOMA IS PRODUCED?
Mouse is immunized with a specific antigen, then
the _____ is harvested.
spleen
Spleen cells are fused with myeloma cells in the
presence of ______, producing hybridoma
polyethylene glycol (PEG)
After fusion, cells are placed in culture containing ______, ______, and _____ to allow selective growth of hybridoma cells
hypoxanthine, aminopterin, and thymidine (HAT)
Hybridoma cells produce ________ which are then harvested
monoclonal antibodies
