A highly specific and sensitive radioimmunoassay of caerulein, an analogue of cholecystokinin-8.
A highly specific and sensitive competitive radioimmunoassay was developed for caerulein (CLN), an analogue of cholecystokinin-8 (CCK-8), in plasma and brain. Antiserum was produced in rabbit by immunization with N delta-[CLN-(1-6)]-ornithine amide conjugated with bovine serum albumin by the glutaraldehyde method. N alpha-[CLN-(1-6)]-lysine amide was labelled with 125I-Bolton & Hunter reagent and used as a labelled antigen after purification by high-performance liquid chromatography. This assay was highly specific for CLN, and cross reactivities for other related peptides, CCK-4, CCK-8, gastrin-I, and gastrin-(14-17), were not observed (less than 0.01%). The limits of determination in biological specimens after CLN administration were 11 pg/ml in human plasma and rat plasma and 80 pg/g in rat brain. This study showed that the slight structure difference between hapten and 125I-labelled antigen is important to the assay performance.
Kominami
G
G
Shionogi Research Laboratories, Shionogi & Co., Ltd., Osaka, Japan.
Mori
S
S
Sagawa
K
K
Igano
K
K
Inouye
K
K
Kono
M
M
D000818:Animals; D000918:Antibody Specificity; D001923:Brain Chemistry; D002108:Ceruletide / Q000097:blood*; D003429:Cross Reactions; D006801:Humans; D010455:Peptides; D011817:Rabbits; D011863:Radioimmunoassay; D051381:Rats
D010455:Peptides; D002108:Ceruletide