Antibodies Flashcards
What are immunogens?
Molecules that will elicit an antibody response
What are antigens?
A molecule that an antibody can bind to
Are all antigens immunogens?
No. All immunogens are antigens, but not all antigens are immunogens
What is the epitope?
The precise sites of antigens that an antibody binds to
What are the two types of epitopes?
Linear and conformational.
Linear = sequence of continuous amino acids
Conformational = formed by amino acids that are brought together by protein folding
What is the general structure of an antibody?
Two identical heavy chains, and two identical light chains. They are in a Y shape.
There is a Fab region, an Fc region and a hinge region
What is the Fab region of antibodies?
The “arms” of the Y shaped antibody, consisting of the variable regions of both heavy and light chains.
It is the region responsible for antigen binding
What is the Fc region of antibodies?
The “stem” of the Y-shaped antibody, consisting of the constant regions of the heavy chains.
It is the region responsible for biological activity mediation
What is the hinge region of antibodies?
Flexible region between the Fab and Fc regions, allowing for antibody flexibility during antigen binding
What does the specificity of an antibody depend on?
The hypervariable regions- these regions are directly involved in antigen binding
What are 5 stages of antibody formation?
- VDJ recombination
- Somatic hypermutation
- Class switch recombination
- RNA splicing
- Affinity maturation
VSCRA
Describe the process and outcome of VDJ switching
Recombination of Variable (V), Diversity (D), and Joining (J) gene segments in developing B cells.
Generates diverse antigen-binding sites in antibodies.
Describe the process and outcome of somatic hypermutation
Introduces point mutations into the variable region of immunoglobulin genes in activated B cells.
Outcome is increased antibody diversity and affinity for the antigen
What immune cell is responsible for producing antibodies?
B cells
What is class switching recombination?
This process alters the constant region of the antibody heavy chain.
Allows B cells to change their class of antibody while retaining antigen specificity, e.g. from IgM to IgG
What is RNA splicing?
Processing of primary RNA transcripts to mature mRNA- removal of introns.
Produces the final mRNA transcript for antibody protein synthesis
What is affinity maturation?
B cells produce antibodies with increased affinity for antigens through cycles of mutation and selection
What are the 4 main biological roles of antibodies?
Neutralisation
Opsonisation
Complement activation
Antibody-Dependent Cellular Cytotoxicity (ADCC)
NOCA MOCHAA UWU
What are the 5 main classes of antibodies?
IgG
IgA
IgD
IgE
IgM
GADEM
GAWD DAYMMM
What is the neutralisation function of antibodies?
Antibodies bind to specific antigens on pathogens, blocking their ability to interact with host cells
Blocking the keyhole
What is the complement activation function of antibodies?
Antibodies bind to specific antigens on pathogens, activating the complement system.
Calling of reinforcements
What is the opsonisation function of antibodies?
Antibodies (and other opsonins like complement proteins) coat the pathogen, marking them for phagocytosis by neutrophils and macrophages
Big label on package to be collected and disposed of
What is the Antibody-Dependent Cellular Cytotoxicity (ADCC) function of antibodies?
Antibodies bind to infected or cancer cells and recruit natural killer cells to destroy them/induce apoptosis
Marking a target for expert marksman
What is the main antibody class involved in NOCA?
IgG
