Factor xv

The factor XV, the Prekallikrein, is present in two similar forms with a molecular weight of 88,000 D and 85,000 D and is detectable in plasma. The concentration is 14-45 ug/ml. Together with the HMWK (see factor XIV below), the Prekallikrein forms a complex that is detectable in the plasma and adheres to negatively charged surfaces.

Prekallikrein is activated by F-XIIa and by HMWK to form Kallikrein, whereby Kallikrein activates F-XII.

Factor XV is prekallikrein, from which kallikrein is produced. Factor XV was discovered by Hathaway in 1965 when a family named Fletcher was admitted to the University Hospital of Kentucky. The family had been living in a mountain cabin that had burned down. This resulted in hypothermia and therefore admission to the hospital. Hathaway discovered that four children in this family had abnormal coagulation and was able to distinguish this from all previously known bleeding disorders by further analysis. He prepared a plasma preparation in which all known clotting factors were removed and, by adding this preparation, was able to compensate for the children's clotting defect. This factor has been called the "Fletcher factor" since that time. The Fletcher and Fitzgerald factor activate the intrinsic pathway before factor XI intervenes. After a functional description, studies by Wuepper discovered that the Flechter factor is the prekallikrein.

1. HA Neumann (2014) The coagulation system. ABW-Wissenschaftsverlag GmbH Berlin S. 70f.