Platelet aggregation in children with acute lymphoblastic leukemia during induction of remission therapy.

摘要

BACKGROUND: Development of thromboembolytic events is a major complication during induction of remission therapy (IRT) for acute lymphoblastic leukemia (ALL) of childhood. Increased in vitro platelet aggregation in response to drugs employed at this stage has been documented. To investigate the presence of an in vivo platelet agonist effect, we studied changes in aggregation patterns of patients with ALL receiving IRT. METHODS: Platelets from 22 children with a new diagnosis of ALL were obtained during IRT once the platelet count reached >100 x 10(9)/L. Platelets were stimulated with adenosine diphosphate (ADP), collagen, ristocetin, and epinephrine. Platelet responses were evaluated by optical aggregometry. RESULTS: Percentages of platelet aggregation in ALL patients were as follows: ADP, 89+/-22; collagen, 90+/-24; ristocetin, 84+/-26, and epinephrine, 81+/-20. Percentages in healthy individuals were ADP: 98+/-12; collagen: 105+/-10; ristocetin: 100+/-15, and epinephrine, 98+/-8. CONCLUSIONS: Platelet aggregation with classical agonists was diminished during IRT for ALL of childhood, although it remained within the normal lower limit for age. Considerable heterogeneity in platelet reactivity existed, probably reflecting the presence of several pharmacologically altered platelet subpopulations. No apparent clinical correlation of aggregometric changes was documented.