Antibody (Immunoglobulin)
Definition
A Y-shaped glycoprotein produced by B lymphocytes that binds a specific antigen at its variable regions. Antibodies used as forensic reagents are produced by immunising an animal (rabbit, horse, or goat) with a specific antigen, then harvesting the resulting antiserum.
- Structure
- Y-shaped glycoprotein with variable binding regions
- Producing cells
- B lymphocytes
- Reagent source animals
- Rabbit, horse, or goat immunised with target antigen
- Harvested as
- Antiserum, containing the resulting antibodies
Common questions
How is a raw antiserum turned into a usable forensic reagent?+
The antiserum is typically purified and titred to confirm it reacts strongly with the target antigen and weakly or not at all with related proteins, then diluted to a working concentration before it is used in tests such as precipitin or lateral-flow assays.
Why do variable regions matter for antibody specificity?+
The variable regions at the tips of the Y shape are the parts that physically contact the antigen, and small differences in their shape are what let one antibody bind tightly to one target while ignoring structurally similar molecules.
Related terms
- Antigen
- A molecule recognised by the adaptive immune system through specific binding to an antibody or T-cell receptor. Defined by immunogenicity (capacity to...
- ELISA (Enzyme-Linked Immunosorbent Assay)
- A plate-based immunoassay format in which a target antigen is captured by an antibody bound to a solid surface, detected by a...
- Lateral-Flow Immunoassay
- A point-of-care competitive immunochromatographic format on a nitrocellulose strip. In the absence of drug, colloidal gold-labelled antibody is captured at a test...
- Precipitin Reaction
- The formation of an insoluble antigen-antibody complex (precipitate) when soluble antigen and antibody meet at equivalent concentrations. The Ouchterlony double-diffusion test and...
- Secretor Status
- A genetic trait that determines whether a person expresses their ABO blood group antigens in secreted body fluids such as saliva, semen,...