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39 Cards in this Set
- Front
- Back
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What is an immunogen?
Antigen? |
Immunogen = Induces an immune response
Antigen = Reacts with products of the immune response |
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What is the relationship between an immunogen and an antigen?
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All immunogens are antigens, but not all antigens are immunogens
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What is an autoantigen?
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A self antigen
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What is an alloantigen?
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An antigenic difference within a species
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What is a xenoantigen?
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An antigenic difference between species
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What is a hapten?
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A small molecule that is covalently attached to a protein carrier
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How does the presence of hapten with a carrier change immunization response?
Hapten alone? |
Immunization with a hapten-carrier conjugate elicits antibodies to both structures
Immunization with hapten alone will not elicit antibodies? |
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What is an epitope?
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Smallest "antigenic" unit
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What are 2 types of epitopes?
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1. Linear or sequential - linear stretch of amino acids
2. Nonsequential or discontinuous - formed by noncontiguous sequences in a molecule that "associate" in its tertiary structure |
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What do most antibodies recognize on an antigen?
How does this affect binding to a denatured antigen? |
Most antibodies recognize shapes of antigens
These antibodies do not bind to denatured antigens |
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How does the 'foreignness' of an antigen affect the immune response?
What do foreign antigens cause? |
The more foreign (phylogenetically distant), the more immunogenic
Innate immune response -> dendritic cells present to adaptive immune system |
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How does molecular weight of an immunogen affect the immune response?
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Poor immunogens < 1000 Da
So so immunogens 1000-6000 Da Good immunogens >6000 Da |
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How does the complexity of immunogens affect the immune response?
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Homopolymers (produced with 1 amino acid) --> limited immunogenicity
Heteropolymers (more complex) --> more immunogenicity |
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How does enzyme degradability of an immunogen affect the immune response?
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If a molecule cannot be digested by an APC, it is not immunogenic (no T cell response)
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How does the immunological status of the host affect the immune response?
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Neonatal, geriatric, immunocompromised people --> poorer response
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In what 2 ways does the genetic makeup of the host affect the immune response?
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1. If person lacks MHC molecules to present certain peptides --> peptides not immunogenic
2. If person lacks TCRs or BCRs to recognize antigens, these antigens will not be immunogenic |
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How does the dose of immunogens affect the immune response?
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Too high or too low dose --> no response
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How does immune response vary with aggregated vs. nonaggregated molecules?
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aggregated = more immunogenic
nonaggregated = less immunogenic |
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How does the route of antigen affect immune response?
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Intravenous and subcutaneous routes are less effective than intramuscular or intradermal
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What can oral antigens do?
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Tolerize or turn the immune response off
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What are 4 types of antigens and to what degree are they immunogenic?
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1. Polysaccaraides - immunogenic when attached to proteins or lipids, associated with ABO blood group
2. Lipids - poor unless attached to protein or are glycolipids 3. Nucleic acids - poor unless conjugated to protein carriers 4. Proteins - virtually all are immunogenic if they are foreign |
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T cells
a. Antigen interaction b. Nature of antigen c. Binding of soluble antigens? d. Epitopes recognized |
a. TCR binds antigenic peptides bound to MHC
b. Peptide c. No d. Internal linear peptides that are produced by antigen processing (proteolytic degradation) |
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B cells
a. Antigen interaction b. Nature of antigen c. Binding of soluble antigens? d. Epitopes recognized |
a. BCR binds antigen
b. Protein, polysaccharide, lipid c. Yes d. Accessible, sequential, or nonsequential |
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What is a requirement for haptens to induce an immune response?
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Must be bound to a carrier molecule
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How do typical haptens work?
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Fit into the binding site of the Ig receptor on the B cell
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What is 'linked recognition'?
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Hapten attached to a carrier taken up by APC --> degraded --> portions of carrier presented as peptides in the grooves of the MHC class II --> TCR recognizes, can now "help" B cell
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What are 3 properties of the primary immune response?
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Low, transient, falls quickly to levels just above baseline
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What are 3 properties of the secondary immune response?
What sets off the secondary response? |
Quicker, greater magnitude, longer lasting
Response due to activation of memory T and B cells |
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What are homologous antigens?
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Have identical epitopes for B or T cells
Same molecule is used for immunization and testing |
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What are heterologous antigen?
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Immunizing molecules are different (but related) from the molecules that the response recognizes
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How can native proteins induce an immune response?
What are 2 instances in which this occurs? |
If chemically modified
Occurs in hypersensitivity, autoimmunity |
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What are heterophile antigens?
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Cross reactions between very unrelated molecules that just happen to share an epitope
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What is an adjuvant?
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An additive that, when mixed with immunogens, make them more immunogenic (but cannot make hapten immunogenic)
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Aluminum hydroxide or aluminum phosphate
a. composition b. mechanism of action |
a. Aluminum hydroxide gel
b. Enhance uptake of antigen by APC, delay release of antigen |
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Alum with a mycobacterial-derived dipeptide
a. composition b. mechanism of action |
a. Aluminum hydroxide gel w/ muramyl dipeptide
b. Enhanced uptake of antigen by APC, delayed release of antigen; induction of co-stimulatory molecules on APC |
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Alum with Bordetella Pertussis
a. composition b. mechanism of action |
a. Aluminum hydroxide gel with killed B. pertussis
b. Enhanced uptake of antigen by APC, delayed release of antigen; induction of co-stimulatory molecules on APC |
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Freund's complete adjuvant
a. composition b. mechanism of action |
a. Oil in water with killed mycobacteria
b. Enhanced uptake of antigen by APC, delayed release of antigen; induction of co-stimulatory molecules on APC |
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Freund's incomplete adjuvant
a. Composition b. Mechanism of action |
a. Oil in water with killed mycobacteria
b. Enhanced uptake of antigen by APC; delayed release of antigen |
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Immune stimulatory complexes
a. Composition b. Mechanism of action |
a. open cagelike structures containing cholesterol and a mixture of saponins
b. Delivery of antigen by cytosol, allowing induction of cytotoxic T cell responses |
