Immunonephelometry and immunoturbidimetry: Theoretical principles, instruments and application

Nephelometry and turbidimetry are methods based on the phenomenon whereby light, passing through a medium with dispersed particles is attenuated in intensity by scattering. The intensity of the scattered light is measured at right angle (usually, but not necessarily) to the incident light beam (nephelometry) or at a forward angle (turbidimetry). Based on nephelometry and turbidimetry, immunonephelometric and immunoturbidimetric assays for the measurement of proteins have developed and expanded rapidly in recent years, progressively replacing the time-honored gel precipitation techniques. In this study, the theoretical background of light scattering theory, instrumental systems for nephelometry and turbidimetry, the nature and kinetics of the antibody-antigen reaction in fluid, and the application of immunonephelometric and immunoturbidimetric assays for specific proteins in the clinical laboratory are described.