Page 1432 - Veterinary Immunology, 10th Edition

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FIG. 42.27 The direct antiglobulin test. The presence of the
antiglobulin is required to agglutinate particles coated with
nonagglutinating antibody.

Passive Agglutination

Since agglutination is a much more sensitive technique than
precipitation, it is sometimes useful to convert a precipitating
system to an agglutinating one (Fig. 42.28). This may be done by
chemically linking soluble antigen to inert particles such as
erythrocytes, bacteria, or latex beads. Erythrocytes are among the

best particles for this purpose, and tests that employ coated
erythrocytes are called passive hemagglutination tests.

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