“…First, the massive destruc tion of leukaemic blast cells may cause the release of procoagulant material, as is ty pically seen in acute promyelocytic leu kaemia; second, chemotherapy may im pair the synthesis of proteins physiologi cally involved in the neutralization of acti vated procoagulant factors. Following Lasparaginase therapy, a significant de crease of plasma antithrombin III (AT III) has been described and this may ac count for the thromboembolic manifesta tions described in rare cases of acute lym phoblastic leukaemia (ALL) [Pitney et al, 1980;Conard et al, 1980;Vellenga et al, 1980;Turaet al, 1981].…”