Flashcards in SI LEC - Antigens Deck (46):
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macromolecules capable of triggering an adaptive immune response by inducing antibodies or sensitized T cells in an immunocompetent host.
IMMUNOGENS-
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substance that reacts with ab or sensitized T cells but may not be able to evoke an immune response
ANTIGENS-
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reasons why we respond to immunogens (3)
Nature of immunogen itself
Genetic coding of MHC molecules that must combine w/ an immunogen before T cells are able to respond
Immunogen processing and presentation
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FACTORS INFLUENCING THE IMMUNE RESPONSE
Age
Overall health
Dose
Route of inoculation
Genetic predisposition
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TRAITS OF IMMUNOGENS
The ability of immunogens to stimulate a host response depends on the ff:
Molecular size
Chemical composition and molecular complexity
Foreigness
Ability to be processed and presented with MHC molecules
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Immunogen must have a MW of at least
10,000 daltons.
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The greater the MW, the ___ the immunogenecity.
more potent
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MW of the best immunogens
Over 100 000 daltons
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are best immunogens based on complexity
Proteins and polysaccharides
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which is more immunogenic, CHON or CHO
CHONS
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EX of nonimmunogenic based on complexity (3)
synthetic polymers
pure nucleic acids
lipids
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usual form of CHO
CHO are usually in the form of glycoproteins (Rh and Lewis ags), glycolipids (ABH antigens)
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Ex of glycoproteins
Rh and Lewis Ags
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Ex of glycolipids
ABH Ag
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Pure nucleic acids and lipids must be attached first to a _____ to be immunogenic
carrier molecule
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are used for artificial heart valves, elbow replacement, and other medical appliances.
Synthetic polymers
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_______ better immunogen for an animal than is material for from a related animal.
Plant proteins
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Any lymphocyte that will ______ will be normally deleted,
react to self Ags
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All ____ are considered immunogenic
non self
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how are Ags processed
enzymatic digestion
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Types of epitope
repeating copies or differing specificities
linear/sequential
conformational
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Molecular shapes or configurations that are recognized by B or T cells
EPITOPE
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Small part of an immunogen that is actually recognized in the immune response
EPITOPE
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w/ epitope of 6-15 aa
PROTEINS
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PROTEINS : w/ epitope of how many aa
6-15
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recognized both linear and conformational epitopes present on the surface of an immunogen.
B cells
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recognized epitope only as a part of the complex formed with MHC on the surface of antigen-presenting cells
T cells
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B cells recognized both ___ (what epitope types) present on the surface of an immunogen.
linear and conformational epitopes
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T cells recognized epitope only as ______ on the surface of antigen-presenting cells
a part of the complex formed with MHC
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Non immunogenic small substances that need to be complexed to larger molecules to be able to stimulate immune response
HAPTENS
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Hapten is able to react to abs, even w/o a carrier molecule.
TRUE or FALSE
TRUE
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Has a single determinant and cannot form cross-links w/ more than one antibody molecule that are necessary for precipitation or agglutination.
HAPTENS
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Why haptens cannot form crosslinks
Has a single determinant
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type of antigen
belong to the host, no immune response
Autoantigens
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type of antigen
from other members of the host’s species,
eg blood ags, ags in tx transplantation, can stimulate immune response
Alloantigens
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type of antigen
from other species
eg plant ag, animal ags, microbial ags
heteroantigens
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type of antigen
heteroags that exist in unrelated plants or animals but are either identical or closely-related in structure so that ab to one can cross react w/ ag of the other.
heterophile Ag
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types of antigen
autoAg
alloAg
heteroAg
heterophile Ag
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Substance administered w/ an immunogen that increases the immune response
adjuvant
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Acts by producing a local inflammatory response that attracts a large no. of immune cells to the injection site.
adjuvant
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Acts by prolonging the existence of immunogens in the area, increasing the effective size of the immunogen, and increasing the no. of macrophages involved in Ag processing
adjuvant
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Freunds’ Complete Adjuvants consists of (3)
mineral oil, emulsifier, and killed mycobacteria (0.5 mg/mL)
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are the only approved adjuvant for clinical use in US.
Aluminum salts
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disadv of Freunds Complete Adjuvants
Freunds’ CA: produces granuloma, or large tissue scars
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adjuvant not used in humans, for research only
Freunds Complete Adjuvant
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