Monoclonal antibodies to chlorinated dibenzo-p-dioxins

A thyroglobulin conjugate of dioxin (thyroglobulin-2 adipamide, 3,7,8-trichlorodibenzo-p-dioxin) (TG-TCDD) was used to immunize BALB c mice. Hybridomas were produced by cell fusion between immune spleen cells and mouse myelomas SP2 0, P3, or NS1. To screen the thousands of resultant cultures for production of monoclonal antibodies (MoAb), a rapid, solid-phase radioimmunoassay for antibody to dioxins was developed. This procedure involved attaching bovine serum albumin coupled with trichlorodibenzo-p-dioxin (BSA-TCDD) to polystyrene plates to be used as a solidphase target antigen for reaction with MoAb. Fourteen hybridomas were identified that produced MoAb reacting with BSA-TCDD but not with BSA alone. Antibodies were tested for binding to BSA-aniline to eliminate those with limited binding specificity. Initial studies indicated that most MoAbs bound BSA-aniline as well as BSA-TCDD. More detailed analyses indicated that while most MoAbs showed some reaction with BSA-aniline, two showed preferential binding to BSA-TCDD of more than 200-fold whereas rabbit antisera demonstrated only a 5-fold discrimination. MoAb 391-1B was purified from mouse ascites fluid and after radioiodination, was tested for direct binding to BSA-TCDD or BSA-aniline. ¹²⁵I-MoAb 391-1B showed no significant binding to BSA-aniline while demonstrating high binding to BSA-TCDD (K_a = 4.5 × 10⁸liters/mol).