Factor VIII/von Willebrand factor abnormalities during L-asparaginase treatment in patients with acute lymphoblastic leukemia.

Factor VIII/von Willebrand factor (VIII/vWf) related properties were studied in 10 patients affected by acute lymphoblastic leukemia during L-asparaginase-vincristine-prednisone treatment. These properties remained within the normal range during the period of observation without any difference from the basal values. On the contrary, VIII:C activity was already increased before medication and showed gradual additional elevation during the observation period, reaching a peak 1 week after discontinuation of L-asparaginase administration. Crossed immunoelectrophoresis of vWf, performed weekly in 2 patients during the period of medication, demonstrated a normal pattern before the beginning of treatment, but an apparently faster migrating peak during L-asparaginase therapy, suggesting a qualitative abnormality of vWf. No abnormal bleeding tendency was found in any of the patients.