Cross-reactivity of various tetrahydrocannabinol metabolites with a monoclonal antibody against tetrahydrocannabinolic acid

Abstract

A monoclonal antibody (MAb-4A4) against Δ9-tetrahydrocannabinolic acid (THCA) was prepared and its cross-reactivity analyzed with various cannabinoids including tetrahydrocannabinol metabolites by competitive enzyme-linked immunoassay (ELISA). Δ9-THC (1-100 μg/ml) could be determined by the ELISA. Many metabolites of Δ8-THC and Δ9-THC reacted with the antibody, and their cross-reactivities were 44-157% of Δ8-THC. However, the antibody did not recognize the lipophilic compounds cholesterol, testosterone, β-carotene, androstene-3,17-dione or an endogenous cannabinoid, anandamide.