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96 Cards in this Set
- Front
- Back
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what does the term antibody mean?
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the term for an immunoglobulin that we know the antigen it is specific for
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what does the term immunoglobulin mean?
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a term for an antibody if we don't know the specificity of the moleucle
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what are the components of an antibody?
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two heavy chains, two light chains, 2 N-termini, C-termini, hinge region, variable regions, constant regions, antigen binding sites
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what components result from proteolytic cleavage if Ig?
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2 Fab and an Fc
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what does Fab stand for?
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Fragment Antigen Binding
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what does Fc stand for?
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Fragment Crystallizable
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what forms the antigen-binding site of an antibody?
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the hypervariable regions
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what are the hypervariable regions of an antibody?
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the antigen-binding site
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where are hypervariable regions that form antigen-binding sites found on?
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antibody
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what are the isotypes of Ig?
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IgG, IgM, IgD, IgA, IgE
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what determines the isotype of Ig?
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the heavy chain genes
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how many isotypes of heavy chain genes are there?
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5
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what do the different llight chain genes encode?
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kappa (κ) or lambda (λ)
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what are isotypes?
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classes of immunoglobulins
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what is another term for the classes of immunoglobulins?
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isotypes
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isotypes are determined by what?
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differences in heavy chains that are encoded by different genes and have different biological functions
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what are subclasses of antigens?
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differences within isotypes that are encoded by different genes that have species variability
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what are the features of IgG?
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2 gamma (γ) heavy chains, 2 light chains, 150kD
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where is IgG found?
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it is the major Ig found in serum, lymph, CSF
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what is a distinguishing feature of IgG?
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it is the smallest IG
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what are the features of IgM?
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900kD, 5Igs linked by J chain, and mu (μ) chain has 4 constant region domains
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where is IgM found?
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in serum and lymph?
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what are the distinguishing features of IgM?
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very larger, first Ig made after antigen exposure, binds antigen very effectively but has difficulty moving out of circulator system
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what type of structure can IgM form?
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pentameric IgM
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what are the features of IgA?
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very low serum levels where it is a monomer, in secretions it is a dimer, alpha (α) chain have 3 domains, and the monomer is 165kD
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where is IgA found?
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saliva, mucus, sweat, tears, milk, low levels in serum
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what is the distinguishing feature of IgA?
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found primarily as a dimer
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what is the heavy chain in IgG?
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gamma (γ) chains
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gamma (γ) chains are found in which Ig?
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IgG
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γ stands for what?
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greek letter gamma
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what is the heavy chain in IgM?
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mu (μ) chains
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mu (μ) chains are found in which Ig?
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IgM
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μ stands for what?
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greek letter mu
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what is the heavy chain in IgA?
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alpha (α) chains
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alpha (α) chains are found in which Ig?
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IgA
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α stands for what?
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greek letter alpha
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what are the features of IgE?
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200kD, epsilon chain has 4 constant region domains, low serum concentrations, found membrane bound
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where is IgE found?
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attached to mast cell and basophil membranes via Fc region and in low concentrations in the serum
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what is the distinguishing feature of IgE?
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bound via Fc region to membranes of mast cells and basophils
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what is the heavy chain in IgE?
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epsion (ε) chains
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epsilon (ε) chains are found in which Ig?
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IgE
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ε stands for what?
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greek letter epsilon
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how many constant region domains are in the epsilon (ε) heavy chain?
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4
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how many constant region domains are in the alpha (α) heavy chain?
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3
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how many constant region domains are in the mu (μ) heavy chain?
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4
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how many constant region domains are in the gamma (γ) heavy chain?
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3
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what are the features of IgD?
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functions as receptor for antigen
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where is IgD found?
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on B cell surface, but not in all species
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what is the distinguishing feature of IgD?
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not a serum antibody
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what is the heavy chain in IgD?
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?
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which Ig isn't found in all species?
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IgD
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what is the function of the Fab region of an antibody?
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antigen binding
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what is the region that binds antigen to antibody?
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Fab region
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Fab regions bind antigen to what?
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antibodies
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what is a unique feature about the antigen binding sites on antibodies?
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identicle to each other
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how many antigen binding sites are on an antibody?
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2
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what do the antigen binding sites of an antibody bind to?
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two identical epitopes
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what are examples of the type of epitopes an antibody might bind to?
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linear and discontinuous
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what is another term for antigenic determinants?
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epitopes
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what is another term for epitopes?
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antigenic determinants
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antigen to antibody binding uses what interactions?
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non-covalent
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what are examples of antigen-antibody interaction?
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antigen valence and antibody valence
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what are non-covalent interations?
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electrostatic forces, hydrogen bonds, van der Waals forces, hydrophobic forces
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what are electrostatic forces?
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attraction between opposite charges
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what are hydrogen bonds?
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hydrogen shared between electronegative atoms (N, O)
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what are van der waals forces?
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fluctuations in electron coulds around molecules oppositely polarize neighboring atoms
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what are hydrophobic forces?
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hydrophobic groups interact unfavorably with water and tend to pack together to exclude water molecules, and involves van der waals forces
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what type of interaction do electrostatic forces cause?
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non-covalent
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what type of interaction do hydrogen bonds cause?
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non-covalent
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what type of interaction do van der waals forces cause?
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non-covalent
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what type of interaction do hydrophobic forces cause?
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non-covalent
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what is the function of the Fc region of an antibody?
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binding to Fc receptors (IgG), complement activation (IgM, some IgG subclasses), transport across epithelial surfaces (IgA & IgM), mast cell degranulation (IgE)
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what is the region that binds antibody to other immune cells?
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Fc Region
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Fc regions bind antigen to what?
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immune cells
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the Fc region, by binding to Fc receptors triggers what?
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phagocytosis by IgG
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the Fc region, by binding to Fc receptors activates what?
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activation of IgM and some IgG subclasses of complement
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the Fc region, by binding to Fc receptors transport what?
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IgA and IgM across epithelial surfaces
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the Fc region, by binding to Fc receptors degranulates what?
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mast cells with IgE
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how does Fc region transport IgA and IgM across epithelial surfaces?
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binds the Ig, receptor mediated endocytosis, transport to apical face of epithelial cell, cleave receptor and bind Ig to mucus through secretory piece
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how does Fc region degranulate mast cells?
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resting mast cell contains preformed granules of histamine/inflammatory mediators, then multivalent antigen cross-links the IgE antibody bound at the mast-cell surfact, causing release of granule contents
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what do Fc regions and Fc receptor binding result in?
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phagocytosis (IgG) and activation of complement (IgM & some IgG subclasses)
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what is a phagosome?
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a membrane-bounded vesicle created by phagositizng a pathogen
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what is a phagolysosome?
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a phagosome that has fused with lysosomes
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what is a membrane-bounded vesicle created by phagositizng a pathogen?
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phagosome
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what is a phagosome combined with lysosomes?
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phagolysosome
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what is neutralization?
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binding of antibodies to bacterial toxins which are ingested and destroyed by phagocyte
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what is opsonization?
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binding of antibodies to pathogens which may also activate complement resulting in ingestion and destruction by a phagocyte
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what is the valence of antigens?
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most are multivalent
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what does multivalent antigens do?
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multiple different antibodies can bind a single antigen or identical antibodies bind multiple repeating epitopes on single antigen
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what is the valence of antibodies?
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most are bivalent (IgM has a theoretical valence of 10 but functional valence of 5)
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what does antigen and antibody valence enable?
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agglutination & precipitation
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what is aggultunation?
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particulate antigen bound and cross linked by antibodies
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what is precipitation?
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soluble antigen bound and cross linked by antibodies
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what is precipitation reliant on?
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equivalence of antigen and antibody (excess antigen or excess antiboy results in immune complexes remaining soluble)
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what can precipitation of antigen/antibody complexes cause?
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glomerulonephritis
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how can we detect antibodies?
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inject into a different species and the antibodies will be strong antigens in the other species, then those antibodies formed in response with respond to framework regions (ie antibodies to feline IgG recognize all feline IgG) & serum protein electrophoresis
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