Agglutination Methods Immunology Review 388
METHOD
Direct agglutination
Hemagglutination
Passive (indirect)
agglutination
Reverse passive
agglutination
Agglutination
inhibition
Hemagglutination
inhibition
Coagglutination
Antiglobulin-mediated
agglutination
PRINCIPLE
Naturally occurring ags on particles (e.g., bacterial ags). Particles
agglutinate in presence of corresponding ab.
Ag-ab rxn that results in clumping of RBCs.
Soluble ags bound to particles, e.g., latex. Particles agglutinate in
presence of corresponding ab.
Ab attached to carrier particles. Particles agglutinate in presence of
corresponding ag.
Competition between particulate ag (reagent) & soluble ag (in spec-
imen) for sites on reagent ab. Lack of agglutination is pos result.
Detects abs to certain viruses that agglutinate RBCs. In presence of
ab, virus is neutralized & hemagglutination doesn’t occur.
Reagent ab attached to carrier bacteria. (Staphylococcus aureusmost
frequently used as carrier. Protein A binds Fc portion of reagent ab.)
Visible agglutination in presence of corresponding ag.
Detection of nonagglutinating ab by coupling with 2nd ab (antihuman
globulin).
APPLICATION
Widal test for typhoid fever. Salmonella
O & H ags used to detect abs in patient
serum. Test no longer common in U.S.
ABO slide typing.
Rheumatoid factor, antinuclear antibody.
Rapid ID of bacteria.
Detection of illicit drugs.
Rubella & other viruses.
Rapid ID of bacteria.
Direct & indirect antiglobulin tests.
Notes: Rheumatoid factor can cause false-pos rxn in agglutination tests because it reacts with any IgG. Heterophile antibodies can cause false-pos rxn in hemagglutination tests.