[Production of monoclonal antibody against diquat and its application for forensic medicine]

The anti-diquat (DQ) monoclonal antibodies with high specificity were produced. An immunogen was synthesized by binding DQ to bovine serum albumin via a diazo-coupled intermediate. BALB/c mice were injected intraperitoneally once a month with 0.25 mg of the immunogen for 5 months. Their spleen cells were fused with P3U1 myeloma cells to get hybridoma clones secreting anti-DQ antibodies. Two anti-DQ monoclonal antibodies (ADM-1, ADM-2) were subtyped to be IgM and IgG3, respectively. A competitive ELISA was developed with ADM-2. More than 0.05 micrograms of DQ was measured without any interference from human serum. The ADM-2 showed high affinity for DQ and no cross-reactivities with paraquat and other analogues. DQ in sera of poisoning patients were successfully determined by the ELISA. On the other hand, the ADM-2 was applicable to the immunohistochemical demonstration of DQ distribution in experimental animals. An avidin-biotin-peroxidase complex method was used in this immunohistochemical study. DQ-intoxicated rats were killed at 3 h, 12 h, 24 h, 3 days and 7 days after intravenous administration of DQ (30 mg/kg). The macrophages containing DQ in the lung started to be observed at 12 h after injection and the number increased till 7 days. From 3 hours after injection, DQ was localized in the epithelial cells of the distal tubules and collection tubules, but not in the glomeruli in the kidney. In the heart, at every time from 3 h to 7 days after DQ administration, a few myocardial cells were positive with the immunohistochemical staining. The ADM-2 was expected to be available in practice of forensic and analytical toxicology.