Spinal fluid procoagulant activity in leukaemic patients treated with intrathecal methotrexate

A procoagulant activity was found in cerebrospinal fluid (CSF) of patients with myelo- or lymphoproliferative diseases on intrathecal therapy with methotrexate, independently of leukaemic CNS involvement. This activity did not correlate with the cell count in CSF and disappeared on storage at -40 degrees C or after filtration with 0.22 nm filters. Dosage of coagulation factors revealed a strong increase in Factor V activity (F. V:C), an increase in Factor VIII procoagulant activity (F. VIII:C) without a correspondent increase in Factor VIII related antigen (F. VIII R:Ag), and an inconstant increase in Factor IX activity (F. IX:C). These activities all disappeared after filtration with 0.22 micron filters but not with 1.2 micron filters. It is concluded that complexes formed by membrane phospholipids and Factor V were responsible for the procoagulant activity lost after storage. The F. VIII and F. IX.-like procoagulant activity was not lost after storage; it was considered unspecific and attributed to thromboplastin-like substances.