Comparative Studies of Polyethylene Glycol Method and Double Antibody Method in α-Fetoprotein Radioimmunoassay

The comparative study between polyethylene glycol (PEG) method and double antibody method in α-fetoprotein (AFP) radioimmunoassay was carried out. The results obtained were as follows. 1. The serum amount needed for the assay was in equal amounts in both methods. 2. A preparation of various reagents was required before assay procedure in double antibody method, but it was not necessary in PEG method. 3. For the separation of bound and free AFP fractions, three-time washings were required in double antibody method, but the washing was not necessary in PEG method. 4. Incubation temperature must be kept at 20℃ in double antibody method, but it was enough at room temperature in PEG method. 5. The assay was completed within one day in PEG method, but it was at least two days in double antibody method. 6. To express the binding ability in standard curve, both B/T and B/Bo could be used in PEG method, but only B/Bo could be used in double antibody method. 7. The standard curve was almost correctly fitted from 0 to 320 ng/ml in PEG method, but it was from 0 to 160 ng/ml in double antibody method. 8. In regard to accuracy and parallelism test, good results were obtained in both methods, and there was a significant correlation between values obtained by both determinations. From the results obtained, PEG method was better and more practical than double antibody method in points of assay procedure and availability even at a high concentration of AFP.