Counter-Immunoelectrophoresis (CIE)
Definition
An accelerated form of gel diffusion in which an electric current drives antigen and antibody toward each other rather than relying on passive diffusion. Reduces reaction time from hours to thirty minutes and produces sharper lines with dilute or degraded samples.
- Also called
- CIE, crossed immunoelectrophoresis
- Driving force
- Applied electric current, not passive diffusion
- Typical run time
- About 30 minutes
- Compares with
- Ouchterlony double diffusion (hours to complete)
- Best suited to
- Dilute or degraded biological stains
Common questions
Why does an electric current speed up the reaction compared to plain gel diffusion?+
In ordinary Ouchterlony diffusion, antigen and antibody spread outward by concentration gradient alone, which is slow. In CIE, the antigen (typically negatively charged at the buffer pH) is driven electrophoretically toward the antibody well, so the two meet far faster and the precipitin line forms in roughly half an hour instead of many hours.
Why is CIE preferred for degraded or dilute forensic samples over standard gel diffusion?+
Directed migration concentrates the reactants into a narrower path rather than letting them diffuse and dilute over a wide area, so even weak or partially degraded antigen from an old or small bloodstain produces a sharper, more readable precipitin line than passive diffusion would.
Related terms
- Antiserum
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- Cross-Reactivity
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- Ouchterlony Double Diffusion
- A gel diffusion technique in which antigen and antibody placed in separate wells in an agar gel diffuse passively toward each other....
- 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...
- Zone of Equivalence
- The concentration range at which antigen and antibody molecules are present in the correct ratio for maximum lattice formation and visible precipitation....