A novel immunization procedure for production of anti-cholecystokinin-specific antiserum of low cross-reactivity.

An anti-cholecystokinin octapeptide (CCK-8) antibody without cross-reactivity with pentagastrin, whose amino acid sequence is identical with the carboxy-terminal portion of CCK-8, was produced by immunization with CCK-8-keyhole limpet hemocyanin and injection of a conjugate of pentagastrin and a copolymer of D-glutamic acid and D-lysine to inhibit production of antibody cross-reacting with pentagastrin.