6.1 Antigen Antibody Lec 6 Flashcards
Antigen aka?
immunogen
what is an antigen?
substance that binds to components of immune response
**foreign molecules which elicit antibody and/or T cell responses directed against them
what is an immunogen
substance that induces an immune response
Epitope
site on antigen recognized by antibody
Homologous antigen
Substance used to induce is same as substance used to react
Heterologous antigen
Substance used to induce is different than substance used to react
Heterophile antigens
Inducer and reactor substances are unrelated
Adjuvant
Substance that is not antigenic but enhances an immune response
what do Adjuvants do?
4
1) Antigen persistence (around longer)
2) Co-stimulatory signals are enhanced
3) Local inflammation is increased universal thing
4) Nonspecific proliferation of B/T cells
what are 3 Adjuvant types added to vaccine?
Which one is still used?
1) Aluminium potassium sulfate (alum)-precipitate= helps with persistance
* *classic example
2) Freund’s incomplete – oils
* not for humans
3) Freund’s complete – oils + heat-killed Mycobacteria *not for humans
Most antigens are what macromolecules?
With what two characteristics?
proteins
1) high molecular weight
2) complex sequence of unique amino acids (EX: only thing that makes botanic D acid unique is the D?)
is an epitope the entire antigen?
NO! only a portion of the entire antigen is
recognized
is an entire antigen required if the epitope is only a portion of it?
YES!
Is the ratio of antigen to epitope 1:1?
NO!
**each antigen has many epitopes
If the antigen isn’t a protein, then what is it?
polysaccharide
*Most good antigens are proteins but some good antigens are polysaccharides
Why do protein antigens have/want many epitopes?
Each epitope with different specificity and can induce different antibodies (IgG, IgA, IgM, IgE)
what the difference between protein and polysaccharide antigens?
Poly has many epitopes with the SAME specificity and usually induced IgM
*Protein have diff epitopes with diff responses
Polysaccharides usually induce only ____?
**
IgM
Antibodies against polysaccharides are usually IgM**
two types of polysaccharides antigens that usually only induce IgM antibodies?
1) lipopolysaccharide
2) capsular dextran
Mycobacterium has what antigen type?
Lipid
why are Nucleic acids poor antigens?
sequestration in nucleoid of bacteria make these poor antigens to induce antibodies
What are haptens?
small non-antigens found all over nature that cannot cause an immune response bythemselves BUT when COUPLED to a large carrier molecule (protein) can induce antibody response
what usually recognizes the carrier epitopes of Haptens?
T cell usually recognizes the carrier epitopes
–then provide info to B-cell for response
what usually recognizes the Haptenated epitopes in natural configuration?
B cell recognizes the haptenated epitopes in their native configuration
**EX: dinitrophenol
difference between hapten and hapten carrier antigen?
- -hapten= one epitope non-antigenic
- -hapten carrier= one epitope antigenic
example of heterologous antigen?
tetanus vaccine
-toxicologically inert but immunologically active
are adjuvants always present regardless of it being a natural or vaccine antigen?
yes
what is a diagnostic tool of autoimmune disease?
antibodies against nucleic acids because there is enough damage to our own cells
dinitrophenol is a good example of?
naturally occuring hapten response where the small dinitrophenol protein attaches to self and we can now recognize it as non-self
