Inhibition Agglutination Assay
Definition
A serological technique for detecting soluble antigens in body-fluid extracts. Known antibody is incubated with the stain extract; if the target antigen is present, it neutralises the antibody, reducing its ability to agglutinate red blood cells in a subsequent indicator step. The degree of inhibition indicates the antigen's presence and relative concentration.
- Field
- Forensic serology
- Detects
- Soluble antigens in body-fluid extracts
- Principle
- Antigen neutralises known antibody before an indicator step
- Readout
- Degree of agglutination inhibition
Common questions
Why is the assay called an inhibition test rather than a direct agglutination test?+
The target antigen does not itself cause visible clumping. Instead it binds and removes antibody from solution, which then shows up as reduced agglutination in the indicator step compared to a control with no antigen present.
What can cause a false inhibition result?+
Non-specific binding, degraded antibody reagent, or cross-reactive substances in the extract can all reduce agglutination without a true target antigen being present, which is why the assay is run alongside positive and negative controls.
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