Glossary of Antigens

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substances that are usually foreign; capable of inducing a specific immune response.
any substance that binds specifically to an Ab or a Tcell receptor
Example of an Ag that is not immunogenic
Penicillin - a hapten that needs a carrier
what 2 properties determine the recognition of a Ab or TcR for an antigen?
-Chemical properties
4 properties of a good immunogen/Ag:
-Chemical composition and heterogeneity
-Large/insoluble Ags for better Processing and presentation.
-Molecular size
-100kDa is good; 5 kDa is bad.
What is a hapten?
a small antigenic molecule that is not immunogenic; to make immunogenic must be coupled with a carrier protein.
substances that enhance the immunogenicity of an antigen
Are B-cell epitopes sequential or non?
Either - can be contiguous amino acid residues, or noncontinuous, brought together by folding of the protein.
What is a major determinant of whehter antibody will bind an antigen or not?
Complementarity of fit.
What types of residues on ?Antigens do Bcell antibodies recognize?
What could be a consequence of denaturing an antigen with Bcell epitopes?
If non-sequential, will destroy the epitopes. These are only epitopes when undenatured.
Are Tcell and Bcell epitopes
External or Internal?
Tcell = internal; hydrophobic

Bcell = external; hydrophilic
What happens to Tcell epitopes on denatured proteins?
Nothing; they're degraded to present on MHC2 anyway
What determines whether an epitope can be a Tcell epitope or not?
If it can bind to both the TCR AND MHC.
4 factors that determine an Individual response to an immunogen:
-Quantity/frequency of administration
-Route of administration
-Use of adjuvant
What difference does genotype make in an individual's response to immunogens?
MHC is pleomorphic; some individuals respond to Ag better than others.
How does quantity/frequency affect reaction to an immunogen?
Quantity - must have enough to elicit a response;
Frequency - boosters/secondary response will have a greater response
3 routes of Immunogen administration:
-Intradermal (into skin)
-Subdermal (just under skin)
4 effects of an Adjuvant:
1. prolong Ag persistence
2. Enhance co-stimulatory signals
3. Induce inflammation (form granuloma)
4. Stimulate lymphocyte proliferation.
what is an Immunodominant epitope?
one that elicits a stronger response than other epitopes on the same protein/molecule.
What antibodies respond when immunizing with a hapten-carrier conjugate?
-Anti-hapten Ab -> most if this is the immunodominant epitope on the complex.

-Anti-carrier+hapten Ab

-Anti-carrier Ab

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