[Gastrin radioimmunoassay with polyethylene glycol method].

125I-labelled gastrin with high immunological activity and high specific radioactivity of 22.2 approximately 25.9 GBq (600 approximately mCi)/mg (0.5 iodine atom/1 gastrin molecule) was prepared by chloramine-T method using the amount of 100 molar ratio of chloramine-T to gastrin. As results of gastrin radioimmunoassay with polyethylene glycol (PEG) method, intra- and interassay coefficient of variation (C.V.) were 3.6 approximately 7.6% and 5.7 approximately 10.4%, respectively. The average recoveries of 2 levels of gastrin added to serum samples were 104 +/- 11.9% and 105 +/- 9.7%. The correlation coefficient of gastrin values obtained with dextrancoated charcoal (DCC) method and present method was r = 0.973. Antibody used in this study have a characteristic to strongly recognize the tyrosin residue at 12 position and the methionyl residue at 15 position on gastrin (1-17).