A Collaborative Study to Establish the 3^rd International Standard for Tissue Plasminogen Activator

Summary

An international collaborative study was organised to replace the 2^nd International Standard (IS) for tissue plasminogen activator (tPA). The 2^nd IS for tPA (86/670) was used to calibrate the replacement Standard, which was selected from two candidate materials included in the collaborative study. Participants were provided with five sets of four samples (A, B, C, D) and asked to use sample A (2^nd IS, 86/670, 850 IU/ml) to determine the activity of B (86/624, approximately 850 IU/ml), C and D (coded duplicates of the same material, 98/714 approximately 11000 IU/ml). A total of 14 laboratories returned results from Europe, USA, Japan and Australia, providing data from 60 independent assays. Four laboratories used a reference method based on a published monograph from the European Pharmacopoeia for Alteplase for Injection, 1998, and the remaining 10 used their own method. Fibrin was used as promoter of tPA activity by 12 out of the 14 laboratories, the remaining two used kits where fibrinogen fragments were the promoter. Data from this collaborative study and the previous study to establish the 2^nd IS for tPA show that tPA from melanoma cells and recombinant tPA from CHO cells are both suitable materials as International Standards. It was agreed that sample C, D, recombinant tPA, 98/714, be established as the 3^rd International Standard for tPA with a potency of 10000 IU per ampoule, calculated as the mean value from laboratories using fibrin as a promoter of tPA activity. The standard was established by WHO in November 2000.

Keywords

Tissue plasminogen activator - international standard - collaborative study

• References

• 1 Gaffney PJ, Curtis AD. A collaborative study to establish the 2nd international standard for tissue plasminogen activator (t-PA). Thromb Haemost 1987; 58 (04) 1085-7.
• 2 Monograph. Alteplase for injection. In: European Pharmacopoeia: European Commission; 2001. supplement: 409-14.
• 3 Beebe DP, Aronson DL. An automated fibrinolytic assay performed in microtiter plates. Thromb Res 1987; 47 (01) 123-8.
• 4 Robbie LA, Booth NA, Croll AM, Bennett B. The roles of alpha 2-antiplasmin and plasminogen activator inhibitor 1 (PAI-1) in the inhibition of clot lysis. Thromb Haemost 1993; 70 (02) 301-6.
• 5 Angles-Cano E. A spectrophotometric solid-phase fibrin-tissue plasminogen activator activity assay (SOFIA-tPA) for high-fibrin-affinity tissue plasminogen activators [published erratum appears in Anal Biochem 1986 Aug 1; 156(2): 524]. Anal Biochem 1986; 153 (02) 201-10.
• 6 Longstaff C, Whitton C. A new simple and accurate assay for plasminogen activators that may be suitable as a reference method. Manuscript in preparation..
• 7 Carlson RH, Garnick RL, Jones AJ, Meunier AM. The determination of recombinant human tissue-type plasminogen activator activity by turbidimetry using a microcentrifugal analyzer. Anal Biochem 1988; 168 (02) 428-35.
• 8 Finney D. Statistical methods in biological assay. 3rd Edition ed. London: Charles Griffen; 1978
• 9 Kirkwood TBL. Geometric means and measure of dispersion. Biometrics 1979; 35: 908-9.
• 10 Kirkwood TB. Predicting the stability of biological standards and products. Biometrics 1977; 33 (04) 736-42.
• 11 Duncan D. T-tests and intervals for comparison suggested by the data. Biometrics 1975; 31: 339-59.
• 12 Ranby M. On the properties of the international standards for tissue plasminogen activator [letter]. Thromb Haemost 1990; 63 (01) 139.