Abstract
A sensitive, specific and reproducible radioimmunoassay for secretin is described.
Antibodies were readily produced against low microgram quantities of synthetic secretin.
The secretin antibodies did not cross-react with the structurally similar G.I.P.,
V.I.P., or glucagon. Synthetic secretin was iodinated using Chloramine "T" and purified
by a two-stage procedure incorporating gel filtration and gradient elution from a
cation-exchange column. Plasma samples were found to produce variable interference
in the assay necessitating the incorporation of secretin-free "blanks" for each patient's
plasma. Production of secretin-free plasma was by incubation of plasma samples at
37°C for 96 hours.
The sensitivity of the assay was 12.5-25 pg/ml. Normal fasting secretin levels were
21 ± S.E. 7 pg/ml. A mean rise in plasma secretin to 220 pg/ml was observed after
intraduodenal acidification.
Key words
Secretin - Radioimmunoassay - Iodination - Antibodies - Plasma Interference - Duodenal
Acidification
1 Supported by Bruce Hall Trust
