Formulation of optimal conditions for an immunonephelometric assay

A method is described for establishing the optimal conditions for an immunonephelometric protein assay. This method has been derived for use on the Hyland PDQ (Travenol Laboratories, Thetford, UK) and Kallestad (Kallestad Laboratories Inc, Chaska, Mn, USA) nephelometers. We have also found it applicable to the Behring nephelometer (Hoechst, London, UK). Using this approach, it is possible to establish an assay on these instruments for any serum protein with a concentration above about 10 mg/l for which a suitable antiserum is available. This method has also proved suitable for developing methods for proteins in urine, CSF, saliva, and amniotic fluid. Proteins in urine may be measured at concentrations as low as 1 mg/l.