CHEMILUMINESCENT ENZYME-IMMUNOASSAY OF CH OLECYSTOKININ IN RAT PLASMAUSING AN IMMUNOAFFINITY COLUMN AS A PRETREATMENT

The cholecystokinin (CCK) plasma concentration of a basal level in a n ormal rat was at a hardly detectable level (a few pg/ml) even using th e highly sensitive chemiluminescent enzyme immunoassay. In this paper, we prepared an anti-CCK F(ab')(2) fragment which was made by pepsin d igestion from the anti-CCK antiserum. The anti-CCK F (ab')(2) fragment was immobilized to the Sepharose 4B gel activated BrCN and packed to column. We have extracted and concentrated CCK in the rat plasma using this column and the CCK assayed by the chemiluminescent enzyme immuno assay (CL-EIA) of CCK. The immunoaffinity column extraction system was more accurate and precise than a reversed phase gel extraction system . The mean recovery of CCK from the rat pooled plasma using the immune -affinity column was 62.2% (n = 12) by the proposed CL-EIA. The mean /- S. E. (n = 3) of the CCK concentration in the fasted rat plasma is 3.54 +/- 0.10 pg/ml. The plasma CCK concentrations of normal rats and those of camostat administrated rats, could be measured by the propose d CL-EIA using the immune-affinity column as a pretreatment.