Manual quantitative method for the study of red cell agglutination using light diffraction by suspended particles

A new manual technique, called the diffractometric technique, for quantitation of hemagglutination is described in this paper. After the equilibrium has been attained in the reaction, the whole product is resuspended in a dense transparent medium in order to obtain a stable suspension. The relative optical extinction produced by this suspension depends on the number and sizes of the suspended particles and on the photodetector geometry. Hence the agglutination percentage of the reaction can be monitored by using a visible light transmittance photometer. The results of this technique compare very well with the ones obtained by applying two other methods, the Dybkjaer and the Ropars methods.