Agglutination is the most common type of antigen-antibody reaction.

Agglutination is the clumping or binding antigen and antibody.

Agglutination reaction is the reaction in which soluble antibody interacts with particulate (insoluble) antigen in the presence of specific electrolytes at a particular temperature and pH, resulting in clumping of particles.




These clumps are better visualized and can be interpreted by naked eyes.

As in agglutination reaction, the antigens are particulate i.e. visible, big and insoluble, So very less amount of antibody can make the agglutination possible.

Due to the above reason agglutination reaction is considered more sensitive than precipitation reaction.

There are various type of particles that involve in such reaction –

• Erythrocytes ,Bacterial cells ,latex particles .
• Agglutinin- The antibodies which are responsible for the formation of clumps with antigens.
• Agglutinogens – The antigens which are aggregates with antibodies

The agglutination reaction includes two steps:

1. Sensitization
2. Formation of large aggregates or lattice formation

HISTORY OF AGGLUTINATION

Two bacteriologists, Herbert Edward Durham (-1945) and Max von Gruber (1853–1927), discovered specific agglutination in 1896.

The clumping became known as the Gruber-Durham reaction. Gruber introduced the term agglutinin (from the Latin) for any substance that caused the agglutination of cells.

French physician Fernand Widal (1862–1929) put Gruber and Durham’s discovery to practical use later in 1896, using the reaction as the basis for a test for typhoid fever.

Widal found that blood serum from a typhoid carrier caused a culture of typhoid bacteria to clump, whereas serum from typhoid- the free person did not. This Widal test was the first example of serum diagnosis.

Austrian physician Karl Landsteiner found another important practical application of the agglutination reaction in 1900.

Landsteiner’s agglutination tests and his discovery of ABO blood groups were the starts of the science of blood transfusion and serology which has made transfusion possible and safer.

Also Read: What is Serology & Serology tests?

MECHANISM OF AGGLUTINATION REACTION

Agglutination reaction takes place in two-phase i.e. sensitization and lattice formation.

I.) Sensitization or primary phase

• • Binding of antigen-antibody takes place.
  • The coating of cells with antibodies occurs in this phase.
  • It is an initial reaction that is rapid and reversible.

II.) Secondary phase

• • Also known as the lattice formation phase.
  • Large aggregates are formed in this phase.
  • Antibody and antigen form a stable network that results in visible clumping of particles.

TYPES OF AGGLUTINATION

1. Direct agglutination
2. Indirect agglutination

DIRECT AGGLUTINATION or ACTIVE AGGLUTINATION

It includes :

• Slide agglutination
• Tube agglutination
• Antiglobulin test
• Heterophile agglutination

INDIRECT AGGLUTINATION OR PASSIVE AGGLUTINATION

It includes :

• Latex agglutination test
• Haemagglutination test
• Coagglutination

APPLICATIONS OF AGGLUTINATIOIN REACTION

1. Agglutination Reaction is used for blood grouping and cross-matching during a blood transfusion.
2. Agglutination Reaction is used as a routine procedure to identify bacterial culture.
3. It is used serological test.
4. It also used to measures the level of certain therapeutic drugs, hormones, and plasma protein.

ADVANTAGES OF AGGLUTINATION REACTION

1. Agglutination is a rapid test.
2. It is easy to perform.
3. Usually, requiring a few minutes.
4. The degree of sensitivity is high.

DISADVANTAGES OF AGGLUTINATION REACTION

1. It is a semi-quantitative test.
2. It may false-negative reaction due to the prozone phenomenon.
3. Prozone phenomenon- In this phenomenon agglutination is absent due to the presence of an excess of antibody, which results in the formation of the poor lattice.

FACTOR INFLUENCING THE REACTION

• Elevation or decrease in temperature
• Motion
• pH
• Class of antibody