Pregnancy-specific β1-glycoprotein (SP1) determined by means of electroimmunoassay, radial immunodiffusion and nephelometry

Abstract A comparison has been made between rocket-immunoelectrophoresis (RIE), radial immunodiffusion (RID) and automated immunonephelometry (AIP) in the assay of pregnancy-specific β 1 -glycoprotein (SP 1 ) in serum from pregnant women. Using RIE an interaction was demonstrated between the various SP 1 -reactive molecular populations causing a bias of up to 10%. An interaction corresponding to this phenomenon cannot be demonstrated when using RID and AIP. When correlating the serum-SP 1 concentration of samples containing various ratios of SP 1 -reactive molecules by means of RIE, RID and AIP, it was demonstrated that there was no correlation between the results achieved using one method compared to the results achieved by either of the other methods. The results achieved using one method can therefore exclusively be judged from reference values determined using the same method. The analysis time is essentially shorter with AIP than with RIE and RID.