Immunoquantitation of thromboxane synthase in human tissues.

Although the formation of TxB2 has been reported for different cells such as monocytes, lymphocytes, granulocytes or fibroblasts and tissues like lung and liver, the corresponding enzyme has not yet been measured. We have established an enzyme-linked immunosorbent assay (ELISA) for measurement of human Tx-synthase with a monospecific polyclonal and a purified monoclonal antibody. ELISA data were verified by either western blots or immunohistochemistry. Next to platelets, blood monocytes were found to have the highest content of Tx-synthase, whereas lung fibroblasts and promyelocytic cells possess only very low levels. In granulocytes and lymphocytes neither Tx-synthase nor its activity could be demonstrated. Among different tissues, lung and liver showed the highest content of Tx-synthase. These data correlate TxB2-synthase activity in a given human tissue with its enzyme content of Tx-synthase for the first time. In view of the frequent involvement of TxA2 in pathological conditions, the technique developed may prove valuable for the characterization of disease states, particularly inflammatory events.