Week 5 S - Antibodies

Vocabulary flashcards for Cells & Immunity lecture review.

Antigenic Determinants (Epitopes)

The part of an antigen that interacts with an antibody or T cell receptor, usually on the surface of macromolecules.

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.

Antibody (Ab) / Immunoglobulin (Ig)

Binding of Antibody (Ab) to Antigen (Ag) facilitates Antigen elimination.

Fab

The fragment of an antibody that contains the antigen-binding site.

Fc

The constant region of an antibody, which mediates effector functions.

Multiple Myeloma

Cancer affecting B cells, leading to uncontrolled proliferation and aberrant synthesis of homogeneous antibodies or their constituent chains.

Bence-Jones Proteins

Isolated light chain dimers excreted in urine by myeloma patients, providing a source of purified immunoglobulin chains for characterization.

Amino Acid Variability Plots (Wu and Kabat plots)

Plots showing the variability of amino acids at different positions in antibody variable domains, revealing hypervariable regions.

Hypervariable Regions

Regions within the variable domains of antibodies that exhibit high amino acid variability and form the antigen-binding site.

Complementarity-Determining Regions (CDRs)

Six loops (3 on VH and 3 on VL) that create the unique antigen-binding cleft of an antibody.

Epitope

The part of the antigen in direct contact with the antibody.

Binding Forces in Ab-Ag Interaction

Reversible, non-covalent forces including ionic, hydrogen bonding, hydrophobic interactions, and Van der Waals forces that contribute to Ab-Ag interaction.

Affinity

The strength of binding between one antigen-binding site on an antibody and one epitope on an antigen.

Avidity (Functional Affinity)

The binding strength between antibody and antigen taking into account the multivalent nature of the interaction (multiple Ag-binding sites, multiple epitopes).

Immunogen

A substance that can generate an immune response; needs to be a macromolecule larger than ~10kDa.

Antigenicity

A substance that can bind to an antibody but may not necessarily generate an immune response.

Carrier

A molecule conjugated to a non-immunogenic molecule to make the latter immunogenic by providing epitopes for helper T-cells.

Hapten

Non-immunogenic molecule that, when conjugated to a carrier, becomes immunogenic.

Cross-Reaction

Antibodies (or mixtures of antibodies in antiserum) typically show a degree of cross-reaction with related antigens

Continuous (Linear) Epitopes

Epitopes that survive denaturation.

Discontinuous Epitopes

Epitopes (non-linear, non-contiguous, conformation-dependent) are usually lost upon denaturation