Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Precipitin is an antibody that reacts with a soluble antigen to form a visible precipitate. It is commonly used in immunological assays to detect the presence of specific antigens.
5 Must Know Facts For Your Next Test
Precipitins are involved in the formation of antigen-antibody complexes that result in a visible precipitate when they react.
The precipitin reaction occurs optimally when the concentrations of antibody and antigen are equivalent, known as the zone of equivalence.
Precipitin tests can be used to identify bacterial species, diagnose infections, and verify the purity of an antigen.
In gel diffusion assays such as Ouchterlony double diffusion, precipitin lines indicate the presence and interaction of specific antigens and antibodies.
Precipitin reactions can be affected by factors such as temperature, pH, and ionic strength.