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