Lecture 4 - Antibody basics Flashcards
Immunogen
A substance which stimulates a specific immune response
Antigen
A substance which is the target of an immune response
Antibody
A serum protein that binds to antigens, made by B lymphocytes
Determinant or epitope
Antibody binding-site on antigen
Does any antigen binding on a BCR stimulate the B cell?
Not necessarily
What is the requirement of antigen binding on BCR to stimulate the B cell?
BCR clustering and oligeromisation is required.
This is achieved when many antigens are bound to a carrie, causing them to be close together.
Can parts of an antigen or antigen-binding site be changed?
Yes, if the change is minor.
EG: Changing an uncharged amino acid for another uncharged amino acid might have little effect
Interactions involved in antibody binding 1) 2) 3) 4)
1) Electrostatic
2) Hydrogen bonding
3) Hydrophobic/hydrophilic
4) Van der Waals forces
Difference between linear and conformational epitopes
Conformational recognition dependent on epitope being in native conformation.
Conformational can only be recognised by antibodies
Linear epitopes can be recognised in denatured proteins.
Linear epitopes recognisable by both antibodies and TCR
Three main types of antibodies against an immunogen
1) Anti-hapten
2) Anti-carrier
3) Anti-hapten/carrier complex
Way to strengthen anti-hapten response
Immunise first with hapten/carrier complex.
Immunise after with same hapten, complexed to a different carrier.
When is cross-reactivity possible?
When an epitope is conserved
What is serology?
Using antibodies to determine structural relatedness of antigens
What are the limitations of TCR recognition?
Can only recognise linear, peptide epitopes
