A Collaborative Study to Establish the 2nd International Standard for Tissue Plasminogen Activator (t-PA)^[*]

Summary

An international collaborative study involving ten laboratories located in eight different countries was undertaken in order to replace the current International Standard (I.S.) for tissue plasminogen activator (t-PA). Two lyophilised candidate preparations of high purity were assessed in comparison with the current I.S. for t-PA using only a clot lysis assay. One preparation (coded 861670) was purified from a cultured melanoma cell supernatant and was about 98% single chain t-PA while the other preparation (coded 861624) was derived from Chinese hamster ovary (CHO) cells following DNA recombinant procedures and was 75% single chain t-PA.

Both candidate preparations of t-PA compared in quite a satisfactory manner with the current I.S. from the viewpoint of the biometrics of parallel line bioassays and both preparations were quite stable for long periods at low temperatures and stable from up to 1 month at temperatures of 20° and 38° C. Both fultil the criteria to serve as a satisfactory Znd International Standard for t-PA. The Fibrinolysis Subcommittee of the International Committee for Thrombosis and Haemostasis recommended the melanoma source t-PA (861670) as the next I.S. in order to maintain continuity with the 1st I.S. which was also a melanomatype preparation. The data from the ten laboratories indicated that each ampoule of the new proposed standard contains 850 international units of t-PA activity by the clot lysis assay. It is planned to present the results of this study to the Expert Committee on Biological Standardization of the World Health Organization at its next meeting and to request that the preparation of t-PA, coded 861670, be established as the 2ndlnternational Standard for t-PA.

Keywords

Tissue plasminogen activator (t-PA) - 2nd International Standard - Clot lysis assay

* This study was conducted in cooperation with the Fibrinolysis Subcommittee of the International Committee on Thrombosis and Haemostasis

• References

• 1 Gaffney PJ, Curtis AD. A collaborative study of a proposed international standard for tissue plasminogen activator (t-PA). Thromb Haemostas 1985; 53: 134-136
• 2 Chmielewskia J, Randby M, Wiman B. Evidence for a rapid inhibitor to tissue plasminogen activator in plasma. Thrombosis Res 1983; 31: 427-436
• 3 Campbell PJ. International biological standards and reference preparations. I: Preparation and presentation of materials to serve as standards and reference preparations. J Biol Stand 1974; 2: 249-258
• 4 Finney DJ. Statistical Method in Biological Assay. 3rd edition. Griffin; London: 1978
• 5 Bliss CI. The Statistics of Bioassay. Academic Press; London: 1952
• 6 Kirkwood T BL, Tydeman MS. Design and analysis of accelerated degradation tests for the stability of biological standards. J Biol Stand 1984; 12: 207-214
• 7 Gaffney PJ, Templeman JH, Curtis AD, Campbell PJ. The stability of tissue plasminogen activator (t-PA). Thromb Haemostas 1983; 50: 650-651