Quantitation of immune complexes by nephelometry.

Laser nephelometry was used to quantitate immune complexes and IgG aggregates in native sera. Sensitivity limits and calibration curves were in good agreement with the C1q binding assay frequently used for measuring immune complexes. Distinction between sera containing lipids or immune complexes was achieved by polyethylene glycol precipitation. Although not superior to other methods for quantitating immune complexes, the nephelometric assay may prove useful as a screening test and has the potential of an antigen-specific immune complex assay.