Monitoring thromboxane in body fluids: a specific ELISA for 11-dehydrothromboxane B2 using a monoclonal antibody.

11-Dehydrothromboxane B2 (11-DHTxB2) concentrations are believed to reflect levels of the in vivo synthesis and release of thromboxane A2. In a specific enzyme-linked immunosorbent assay (ELISA) a monoclonal antibody (MAB) against 11-DHTxB2 (MAB-1E-DHTBR1) recognizes the acyclic form of 11-DHTxB2, as found in the basic range of pH, with a detection limit of 4.6 pg/sample and a binding affinity of 6.1 x 10(9) l/mol. Negligible cross-reactivity was found for thromboxane B2 (0.05%), 2,3-dinor-thromboxane B2 (0.06%), and prostaglandin D2 (0.08%). Validity of the assay was confirmed by a good correlation between radioimmunoassay and ELISA (r = 0.972). Recovery experiments showed an accuracy of r = 0.982. Measurements of 11-DHTxB2 in human serum and urine samples demonstrated the practical applicability of the MAB in ELISA. With the use of different clotting times, the serum level of 11-DHTxB2 ranged from 0.8-1.3 ng/ml (30 min) to 24.1-47.9 ng/ml (4 h). After administration of aspirin the 11-DHTxB2 level of human urine declined from 3.9-5.4 ng/ml to 0.4-1.6 ng/ml after 6 h.