W4 - ANTIGEN Flashcards
Capacity to STIMULATE the production of antibodies or cell-mediated immune response.
Immunogenicity
Ability to COMBINE the production of antibodies or cell-mediated immune response
Antigenicity
Low molecular weight particles that can bind to an antibody that can elicit an immune response ONLY WHEN THEY ARE ATTACHED to a macromolecule carrier
Haptens
Reaction elicited by hapten w an antibody
Agglutination or precipitation
Antihypertensive drug (hapten) that binds in the RBC to become a complete antigen
Methyldopa
Once Methydopa becomes a complete antigen it will now trigger the release of 3 antibodies:
Anti-Methyldopa
Anti-RBC
Anti methyldopa + red cell
The usage of METHYLDOPA will cause the person to suffer from ?
Drug induced hemolytic anemia
(Jaundice, elevated bilirubin, liver diseases)
SPECIFIC SITES of antigens where antibodies bind.
epitopes
Epitopes is also known as
Antigenic Determinant Sites
epitopes found inside the cell
Inaccessible epitops
Where does the antigen attach to the antibody?
FAB region of the antibody, specifically in the hypervariable region
usally present in the surface of the antigen can act as POINTS OF INTERACTION for specific antibodies
Antigenic molecules
Specific site on the antigen that is recognized by the
MHC molecule
agretope
The site in the VARIABLE (V) DOMAIN of an antibody or T-cell receptor that BINDS TO AN EPITOPE on an antigen
Paratopes
● Shorter but continuous amino acid sequence
● After denaturation, it will still remain INTACT and can STILL BIND to an ANTIBODY
LINEAR EPITOPES (SEQUENTIAL / CONTINUOUS)
The site in the VARIABLE (V) DOMAIN of an antibody or T-cell receptor that BINDS TO AN EPITOPE on an antigen
Paratopes
● Domains of proteins are composed of specific regions of protein chains; longer
● After denaturation, it will break into SMALLER FRAGMENTS fragments; it can NO LONGER BIND to antibodies
CONFORMATIONAL EPITOPE (NONSEQUENTIAL / DISCONTINUOUS)
2 types of epitopes based on their locatoons
Accessible epitope (surface)
Inaccessible epitope (intracellular)
○ Present on the surface of the antigen
○ Recognized and acted upon by B CELLS (have surface immunoglobulins)
An epitope that needs to bind to an antigen-presenting cell (APC); found within antigen
Inaccessible epitope
Function of APCs
Engulf, process, and present the antigens to the T-cells
Type or STRUCTURE of the epitopes
Determinant
Number of ANTIGEN-BINDING SITES on the epitopes
Valence
One type of epitope, one antigen-binding site
UNIDETERMINANT, UNIVALENT
One type of epitope, multiple binding sites
UNIDETERMINANT, MULTIVALENT
Multiple types of epitopes, but only one binding site
for each type of epitope
MULTIDETERMINANT, UNIVALENT
Multiple types of epitopes, multiple binding sites for
each type of epitope
MULTIDETERMINANT, MULTIVALENT
Traits of immunogens
ABO antigens
Influenza virus hemagglutinin
Bacterial capsule
composed of glycolipids
ABO Antigens
Composed of glycoproteins
Influenza virus hemagglutinin
composed of polysaccharides
Bacterial Capsule
degree to which antigenic determinants (epitopes) are recognized as non-self
Foreignness
cells that cannot be recognized by immune system because no introduction of the cell happened during the embryonic development
Sequestered antigens
Self antigens
Autologous antigens
Have the same genetic components with
another person
Syngenic antigen
“Homologous antigens”
Shared by individuals of the SAME SPECIES
Allogeneic antigen
Antigens shared by individuals of UNRELATED SPECIES but have the SAME SHARED ANTIGEN
XENOGENEIC / HETEROLOGOUS ANTIGEN
An immunologic reaction in which the immune
components, either cells or antibodies, REACT WITH 2 MOLECULES that share SIMILAR EPITOPES but are otherwise DISSIMILAR
Cross reactivity
Antibody reacts w M protein and the heart (have similar structures)
Streptococcus pyogenes (M protein) + heart valves = ?
Rheumatic heart disease
Start of the immune response
engulfment of the antigen presenting cell.
Breaking down of the antigen = immune response
Degradability
Antigen: not damaged and is degradable
✅ Immune response
Antigen: undegradable and unstable
NO immune response
Factors directly related to the antigen (5)
Foreignness
Degradability
Molecular weight
Structural stability
Chemical complexity
Many epitopes present = ? MW
High MW
considered to be the most effective and immunogenic antigens because of a large MW
Proteins
● Small foreign molecule that is not immunogenic
● Must be coupled to a carrier molecule to be immunogenic
Hapten
> 10kD
Immunogens
> 100kD
Strong immunogens
<10kD
Poor immunogens (Haptens)
constant stimulation of our immune system =
? immune response.
HIGHER
Solidity and strength of molecule makes it an effective antigen
Structural stability
Antigen is bounded to ? = unstable, poor antigen, easily degraded
Gelatin
Substance administered with an immunogen that increases the immune response
Adjuvants
acts to accelerate, prolong, or enhance antigen-specific immune responses (adaptive immunity) when used in combination with specific vaccine antigens
Adjuvant
Adjuvants enhance immune response by
○ PROLONGING the EXISTENCE of immunogen
○ INCREASING the effective SIZE of the immunogen
○ INCREASING the NUMBER of MACROPHAGES involved in antigen processing
NEW ADJUVANTS
Rapid response to pathogens
Vaccine response broadening
Vaccines for elderly
