Enzyme immunoassay of human plasma 11-dehydrothromboxane B2.

11-Dehydrothromboxane B2 (11-dhTXB2) is a proposed marker compound for thromboxane A2 formed in vivo. An enzyme immunoassay was established for determination of the plasma concentration of this compound. The assay was based on a horseradish peroxidase-linked immunoassay utilizing polyclonal anti-11-dhTXB2 antibody obtained from a rabbit, and enabled determination of 11-dhTXB2 in the range of 2 to 500 pg/tube with an IC50 of 36 pg. The cross-reactivities with TXB2, 2,3-dinor-TXB2 and other prostanoids were less than 0.05%. Validity of the enzyme immunoassay was confirmed by a radioimmunoassay utilizing a monoclonal antibody. The plasma 11-dhTXB2 was immunoaffinity-purified by one step using an immobilized monoclonal antibody. The mean plasma level of 11-dhTXB2 in six male volunteers was 4.0 +/- 0.3 pg/ml by this enzyme immunoassay.