intro to antibodies Flashcards
(18 cards)
What are the two main types of immune systems?
Innate and Adaptive
Innate is also known as natural immunity, while adaptive immunity includes humoral (B cells) and cell-mediated (T cells) responses.
What is an ANTIGEN?
Any substance (usually foreign) that binds specifically to an antibody or T cell receptor (TCR)
Examples include viruses, bacteria, fungal spores, pollen grains, mismatched tissue grafts, and foreign macromolecules.
What are ANTIGENIC DETERMINANTS also known as?
Epitopes
These are usually features of surface macromolecules.
What is the basic structure of an antibody (IgG)?
2 identical light chains and 2 identical heavy chains
Total molecular weight is approximately 160 kDa.
What causes the cross-linking of polyvalent antigens by IgG?
IgG must have at least 2 antigen-binding sites
This leads to agglutination of antigens.
Who were awarded the Nobel Prize for elucidating the chemical structure of antibodies?
Gerald Edelman and Rodney Porter
They received the prize in 1972.
What are hypervariable regions in antibodies?
Regions that provide specificity for binding to antigens
These regions are crucial for creating diverse antibody specificities.
What is the role of a carrier in immunology?
A molecule that makes a non-immunogenic molecule immunogenic when conjugated
For example, a hapten like DNP can be made immunogenic when coupled to hen egg albumin.
What is the distinction between immunogenicity and antigenicity?
Immunogenicity refers to the ability to generate an immune response, while antigenicity refers to the ability to bind to an antibody
An immunogen must be a macromolecule typically greater than ~10 kDa.
What are the four binding forces that contribute to antibody-antigen interaction?
Ionic, Hydrogen bonding, Hydrophobic interaction, Van der Waals force
Each of these forces is reversible and non-covalent.
What is the difference between affinity and avidity in antibody-antigen interactions?
Affinity is the strength of binding between one antibody binding site and one epitope, while avidity considers multivalent interactions between antibodies and antigens
Avidity is the overall binding strength in mixtures of antibodies.
What defines a hapten?
A small molecule that can elicit an immune response only when attached to a larger carrier molecule
Haptens alone cannot generate an immune response.
What does the term ‘cross-reaction’ imply in the context of antibodies?
Antibodies typically show a degree of cross-reaction with related antigens
This can affect the specificity and efficacy of antibody responses.
What is the approximate size of the antigen-binding cleft of an antibody?
2 x 1 x 0.5 nm
This size allows it to fit approximately 6 amino acid residues or 6 sugar groups.
What is the role of water molecules in antibody-antigen interactions?
Water molecules contribute to binding energy by creating additional hydrogen bonds
They fill spaces between the antigen and the antibody.
What is the significance of the Ig superfamily?
Includes various molecules like TCR, Fc receptors, and MHC molecules that share similar immunoglobulin domains
These structures arose from gene duplication of a common ancestral Ig domain gene.
What is the result of antigen challenge on antibody production?
Generates multiple antibodies directed at different epitopes
This increases avidity and enhances the efficiency of antigen elimination.
How many different antibody specificities can each individual generate?
~10^8 different Ab specificities
This diversity arises from a limited number of genes through rearrangement and recombination.
