Nicotine antibodies: comparison of ligand specificities of antibodies produced against two nicotine conjugates.

Conjugates between bovine serum albumin and (R,S)-2-aminonicotine were produced, and these conjugates were employed in rabbits and goats for the production of nicotine antibodies. In the assay of nicotine, an 125I-tyrosine methyl ester derivative of (R,S)-6-aminonicotine was employed as radioligand. The antibody-bound derivative was separated from the free derivative by charcoal adsorption (0.5% charcoal, 0.1% dextran T-70, 0.1% bovine serum albumin pH 7.3). Among the twenty five nicotine derivatives and metabolites examined, (R,S)-6-aminonicotine gave the highest cross-reaction. Cross-reaction with cotinine, a major mammalian metabolite of nicotine, was less than 0.1% for both the rabbit-derived and goat-derived antisera. Cross-reaction by other metabolites, such as (S)-nicotine-N'-oxide, (S)-nornicotine, and N-methylpyrrolidine was less than 1%. The antibodies produced were thus highly specific to nicotine. The radioimmunoassay for nicotine showed a maximum sensitivity of 10 ng/ml in 50-microliter plasma samples for both antisera. After the smoking of a single cigarette (1.2 mg nicotine content in mainstream) the peak of blood plasma level of nicotine in the subjects varied from 20--104 ng/ml, and high levels of nicotine were not necessarily found in heavy smokers.