Kinetics of the antigen:antibody reaction. Light scattering and particle size measurement using photon correlation...

Many techniques for the estimation of specific proteins measure light scattered by, or the turbidity of, suspensions of antigen:antibody aggregates formed in fluid-phase reactions. Although the shapes of reaction curves obtained are well documented, interpretation of the data in relation to the laws of light scattering and the mechanism of the antigen:antibody reaction are poorly described in the literature. Using photon correlation spectroscopy it has been shown that antigen:antibody complexes continue to grow in size even when no further increases in scatter intensity or turbidity are apparent.