[Development of a rapid method of immunoassay of C reactive protein by polarization of fluorescence]

Increased level of C reactive protein in the serum of neonates indicates the presence of infection, whereas the classic signs (hyperthermia, neutrophilia...) may often fail. So the determination of C reactive protein is useful and has to be rapidly performed on a small quantity of blood. The authors evaluate a fluorescence-polarization immunoassay (TDX Abbott System), and compare this method to the radial immunodiffusion (RID) and the laser immunonephelemetry. Sensitivity (detection limit = 10 mg/l), reproducibility (cv less than 5 p. cent), linearity (until 243 mg/l), are satisfactory. The assay correlates well with RID (r = 0.98, p less than 0.001) and laser immunonephelometry (r = 0.93, p less than 0.001). The proposed method is rapid (10 minutes), requires small quantities of blood (less than 100 microliters), and is not influenced by important amounts of haemoglobin, bilirubin or triglycerides. Thus, this method provides a good means for C reactive protein determination, especially in neonates.