Production of antibodies and development of a radioimmunoassay for okadaic acid.

An okadaic acid immunogen, prepared by conjugation of okadaic acid to bovine albumin with carbodiimide, was used to immunize two rabbits. The rabbits responded by producing antibodies that neutralized okadaic acid's stimulation of arachidonic acid metabolism and this neutralization increased during the course of immunization. The immune sera bound 3H-okadaic acid and this binding also increased with repeated immunization. After absorption of the rabbit IgG with a goat anti-rabbit IgG, binding was reduced greater than 99%. The binding of okadaic acid to the antibodies in one antiserum was inhibited by as little as 0.2 pmoles of unlabelled okadaic acid. The apparent association constant for binding with this antiserum was 4.17 x 10(9) M-1 (35 degrees C). Maitotoxin, teleocidin, 12-O-tetradecanoylphorbol-13-acetate, aplysiatoxin, palytoxin and brevetoxin B when tested at 29, 228, 168, 169, 3.7 and 112 pmole levels, respectively, did not inhibit binding. The serologic and biological activities of okadaic acid after incubation for 60 min in 0.01 N HCl at 35 degrees C or at 100 degrees C at pH 7.2 were unaffected.