Nephelometry and turbidimetry

The nephelometric quantification is based upon the specific reaction of a monospecific anti-IgG subclass-specific antiserum with the human IgG subclass to be determined. The generated immune complexes are quantified by measuring the side-scattered light. A distinct advantage of nephelometry is the relatively short incubation time. As another advantage, nephelometry assays may be readily automated and are therefore suitable for the routine measurement of IgG subclasses in large numbers of samples.

Fixed time-nephelometry is illustrated in figure 8.

Brief outline of the method:

-Diluted samples (serum,plasma or other biological fluids),standard-and control sera are introduced in the reaction tubes of the nephelometer;

-Appropriate anti-IgG subclass reagents and reaction buffer are added;

-Side-scattered light is recorded;

-IgG subclass concentrations in the test samples are calculated relative to the calibration curves, obtained with the nephelometric IgG subclass standard serum;

-A control serum is assayed to check the validity of the calibration curves and the accuracy of the IgG subclass determinations.

Turbidimetry is similar to nephelometry in that it is based upon the fluid-phase optical detection of antigen complexes. However, in turbidimetry the decrease in light transmission is recorded, rather than the side-scattered light, which is measured in nephelometry.