Radioimmunochemical quantitation of sulfated and non-sulfated gastrins in serum

A radioimmunochemical procedure which distinguishes sulfated from non-sulfated gastrins has been developed. Two antisera raised against synthetic non-sulfated human hexadecapeptide gastrin were used. No. 2604 binds sulfated and non-sulfated gastrins with equimolar potency, whereas No. 2605 reacts poorly with sulfated gastrin (ID50 for non-sulfated gastrin: ID50 for sulfated gastrin = 0.06). Both antisera bind gastrins of different molecular length with equimolar potency using monoiodinated human gastrin-17 as tracer. The method was validated by fractionating gastrins in serum and in tissue extracts, and by recovery experiments. We found that Component I of gastrin--like the smaller gastrin components--was present in both, sulfated and non-sulfated form. In serum from normal fasting subjects the concentration of non-sulfated gastrin was 12.5 +/- 0.8 pmol/l (mean +/- SEM) with a total range of 0-44 pmol/l and the corresponding values for sulfated gastrin were 7.5 +/- 0.5 pmol/l (range 0-20 pmol/l). Sulfated gastrin accounted for more than half of the gastrins in only 21% of normal subjects. There was a parallel rise and fall in sulfated and non-sulfated gastrins after a meal and after stimulation with adrenaline.