Agglutination

Agglutination


Agglutination 

  • Sensitive than precipitation reaction for detecting antibodies.
  • Agglutination is a two-step reaction.

The primary reaction:

  • Binding of the Fab portion of antibody to antigenic determinants on the particulate antigen.

The secondary reaction:

  • Cross-linking by multivalent antibodies, of the particles of multivalent antigen to form aggregates.
  • The most obvious clinical application of agglutination is blood-typing;
  • erythrocyte blood group surface antigens (e.g., the ABO blood group factors) 
  • react with antibody that is specific for these allo-antigens to produce agglutination.
  • The cross- matching of blood depends upon this technique.

Agglutination is of following types:

Slide agglutination

  • used for blood grouping and cross matching.

Tube agglutination

  • Widal test Brucellosis
  • Weil-Felix reaction
  • Paul Bunnel test
  • cold agglutination
  • Streptococczs MG test.

Antiglobulin

  • Coombs test
  • used for detecting incomplete Ab of brucellosis
  • anti- Rh Ab.

 Passive agglutination test

  • used to detect Ab
  • by adsorbing soluble Ag on carrier particles so precipitation reaction converts into agglutination test 
  • more convenient and more sensitive.
  • e.g. Rose waller test, test detecting RA factor by using amboceptor.

Latex agglutination test

  • latexfixation test
  • for detection of ASO, CRP, RA factor
  • HCG; Streptozyme test.
  • Rapid test for acute Pyogenic meningitis

Reversed passive agglutination 

  • Estimation of antigen by adsorbing antibody to carrier particles.

Heterophilic agglutination reaction

  • Some organisms of different class or species share closely related antigens.
  • When serum containing agglutinin (antibody) of one organism gives agglutination reaction with antigen of other organism.
  • Examples are
  • Streptococcus M.G. agglutination test for primary atypical pneumonia.
  • Weil – Felix reaction for typhus fever
  • Paul Bunnell test fin- IMN.
Exam Question
 

Agglutination 

  • Sensitive than precipitation reaction for detecting antibodies.

Agglutination is of following types:

Slide agglutination

  • used for blood grouping and cross matching.

Tube agglutination

  • Widal test Brucellosis
  • Weil-Felix reaction
  • Paul Bunnel test
  • cold agglutination
  • Streptococczs MG test.

Antiglobulin

  • Coombs test
  • used for detecting incomplete Ab of brucellosis
  • anti- Rh Ab.

 Passive agglutination test

  • used to detect Ab
  • by adsorbing soluble Ag on carrier particles so precipitation reaction converts into agglutination test 
  • more convenient and more sensitive.
  • e.g. Rose waller test, test detecting RA factor by using amboceptor.

Latex agglutination test

  • latexfixation test
  • for detection of ASO, CRP, RA factor
  • HCG; Streptozyme test.
  • Rapid test for acute Pyogenic meningitis

Reversed passive agglutination 

  • Estimation of antigen by adsorbing antibody to carrier particles.

Heterophilic agglutination reaction

  • Some organisms of different class or species share closely related antigens.
  • When serum containing agglutinin (antibody) of one organism gives agglutination reaction with antigen of other organism.
  • Examples are
  • Streptococcus M.G. agglutination test for primary atypical pneumonia.
  • Weil – Felix reaction for typhus fever
  • Paul Bunnell test fin- IMN.
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