Precipitation and agglutination reactions are the prevalent immunological methods for the detection of antigen and antibody. The significant differences between precipitation and agglutination reaction are due to the following properties like the size of the antigen, solubility of antigen and sensitivity of the reaction.
Size: The size of antigen in precipitation reaction is larger in comparison to the agglutination reaction.
Solubility: In a precipitation reaction, the antigen is in soluble form whereas, in an agglutination reaction, the antigen is in sedimented form.
Sensitivity: Agglutination reaction is more sensitive in comparison to the precipitation reaction.
Content: Precipitation Vs Agglutination Reaction
- Comparison Chart
- Definition of Precipitation Reaction
- Definition of Agglutination Reaction
- Standard Curve for Lattice Formation
- Key Differences Between Precipitation and AgglutinationReaction
|Properties||Precipitation reaction||Agglutination reaction|
|Definition||It is the antigen antibody reaction where the antibody reacts with the soluble antigen to form precipitin||It is the antigen antibody reaction where the antibody reacts with the soluble antigen to form agglutinin|
|Size of an antigen||larger||Comparatively smaller|
|Solubility of antigen||Soluble form||Sedimented form|
|Sensitivity||Less sensitive||More sensitive|
|Media used||Either liquid or gel matrix||Does not require|
|Types||It is of three types: Precipitation in solution, precipitation in agar by diffusion and electrophoresis||It is of two types: Active and passive agglutination|
|Matrix||Precipitation reaction can be performed on glass slides, petri plates and test tubes||Agglutination reaction can be performed on microtitre plate, glass slides and test tubes|
|Formation of resulted compound||Either found as suspension or sink to the bottom||The end product sinks to the bottom|
|Appearance of end product||Appear as large, insoluble mass of visible precipitate||Appear as large visible aggregates|
Definition of Precipitation Reaction
Precipitation reaction can define as the immunological reaction where visible precipitate forms as a result of cross-linkage between antigen and antibody. The resulted compound in precipitation reaction refers as “Precipitin” which is a precipitate formed by the antibody on reaction with the antigen.
Definition of Agglutination Reaction
Agglutination reaction can define as the immunological reaction where a mass of aggregates form as a result of clumping between antigen and antibody. The resulted compound in this reaction refers as “Agglutinin” which is a mass of aggregates formed by the binding of antibodies to the specific antigenic sites.
Standard Curve for Lattice Formation
In both precipitation and agglutination, there are three zones namely pro-zone, post-zone and zone of equivalence.
Pro-zone: It forms when the antibodies are in excess. Pro-zone gives a negative result for both precipitation as well as agglutination reaction. This does not form the immunocomplex or antigen-antibody complex.
Zone of equivalence: It forms when the concentration and ratio of both antigen and antibody are present in equal proportion. Zone of equivalence gives a positive result for precipitation as well as agglutination reaction by the lattice formation.
Post-zone: It forms when the antigens are in excess. Post-zone also gives a negative result for both the reaction and does not form the immunocomplex.
For the lattice formation, there is a standard curve where at the zone of equivalence, the precipitation and agglutination reaction occurs. To prepare the standard curve, one reactant is kept constant, i.e. Antibody and the other reactant, i.e. Antigen is kept in an increasing concentration. Therefore by the increasing concentration of antigen and constant volume of antibody, three zones will form that is shown in the diagram given below.
- Both precipitation and agglutination reaction are the two most common serological tests.
- Precipitation, as well as agglutination reaction, can be used for the quantitative study of antigen and antibody.
- Agglutination and precipitation reaction requires both the reactants, i.e. antigen and antibody to form an immunocomplex or lattice.
Key Differences Between Precipitation and Agglutination Reaction
- Precipitation reaction can define as the serological test in which the antibodies form a precipitate on the reaction with specific antigen will refer as “Precipitins” which will appear as insoluble visible mass. Agglutination reaction can define as the serological test in which “Agglutinins” forms which are the antibodies that combine with their respective antigens in the form of visible aggregates.
- The size of antigen in precipitation reaction is larger than the agglutination reaction.
- The antigen in precipitation reaction is in soluble form whereas in agglutination reaction the antigen is in sedimented form.
- The sensitivity of agglutination reaction is more than that of a precipitation reaction.
- In a precipitation reaction, both liquid and gel media can be used whereas agglutination reaction does not require media support.
- A precipitation reaction is mainly of three types namely precipitation in solution (Includes ring and flocculation test), precipitation by diffusion (Includes Oudin, Ookley Fulthorpe, Radial and Ouchterlony immunodiffusion) and precipitation by electrophoresis (Includes rocket and counter-immunoelectrophoresis). But an agglutination reaction is mainly of two types namely active and passive types.
- Precipitation reaction can be performed on glass slides, Petri plates and test tubes whereas Agglutination reaction can be performed on microtitre plate, glass slides and test tubes.
- The resulted compound of precipitation reaction refers as “Precipitins” which either forms as suspension or at the bottom. The resulted compound of agglutination reaction refers as “Agglutinins” which forms at the bottom.
- The end product in precipitation reaction appears as a large, insoluble mass of visible precipitate. But, in an agglutination reaction, the end product appears as a large mass of visible aggregates.
Therefore, precipitation and agglutination reactions are the serological methods which involve an antigen and antibody reaction. In both, the cross-linkage between antigen and antibody results in the formation of immunocomplex or lattice. For the reaction to occur, the ratio of antigen and antibody must be equal. It there is any change in the ratio of either antigen or antibody, the formation of a lattice will not occur.