Agglutination research paper

Microtiter plates have an array of wells to hold small volumes of reagents and to observe reactions (e.g., agglutination) either visually or using a specially designed spectrophotometer. The wells come in many different sizes for assays involving different volumes of reagents. Figure 1.

The method developed by Lancefield is a direct agglutination assay, since the bacterial cells themselves agglutinate. A similar strategy is more commonly used today when identifying serovars of bacteria and viruses; however, to improve visualization of the agglutination, the antibodies may be attached to inert latex beads .

However, the presence of IgG bound to red blood cells can be detected by adding Coombs’ reagent, an antiserum containing antihuman IgG antibodies (that may be combined with anti-complement) (Figure 4). The Coombs’ reagent links the IgG attached to neighboring red blood cells and thus promotes agglutination.

The use of agglutination tests to identify streptococcal bacteria was developed in the 1920s by Rebecca Lancefield working with her colleagues A.R. Dochez and Oswald Avery. She used antibodies to identify M protein, a virulence factor on streptococci that is necessary for the bacteria’s ability to cause strep throat.