Double-immunodiffusion assay for detecting specific antibodies

Curr Protoc Immunol. 2001 May;Chapter 2:Unit 2.3. doi: 10.1002/0471142735.im0203s00.


Double immunodiffusion owes its success to the unique nature of antibody-antigen interactions. When polyvalent antibodies with moderate-to-high intrinsic affinities are mixed with antigen at the right ratio (called the zone of equivalence) lattices of antibody-antigen complexes form and precipitate out of solution. When, as described in this unit, gradients of antigen and antibody are established by diffusion from adjacent wells in a bed of agar, a line of practically insoluble precipitation forms at the equivalence zone (precipitin lines).

Publication types

  • Review

MeSH terms

  • Animals
  • Antigen-Antibody Complex / chemistry*
  • Antigen-Antibody Complex / immunology
  • Antigens / chemistry*
  • Antigens / immunology
  • Humans
  • Immunodiffusion / methods*


  • Antigen-Antibody Complex
  • Antigens