Characterization of platelet activity in neuroblastoma

A study was conducted to characterize the platelet aggregation induced by neuroblastoma tissue to investigate the mechanism of hypercoagulability in patients with neuroblastoma. The patients whose tumor tissues were examined had been shown clinically to have enhanced platelet activity. Platelet aggregation induced by neuroblastoma tissue extract was compared with that of other pediatric tumors. The effects of pretreatment with an antithrombin agent and prostacyclin (PGI2) on the platelet aggregation induced by tumor tissue extracts were also evaluated. Tissue extracts of 12 of 15 neuroblastomas, 3 of 3 Wilms' tumors, and 1 pheochromocytoma were demonstrated to have an activity that potentiated platelet aggregation in vitro. The platelet aggregation induced by tissue extracts of neuroblastomas and other tumor tissues was suppressed almost completely by pretreatment with a PGI2 analogue. The aggregation induced by neuroblastomas and the pheochromocytoma was also suppressed by pretreatment with an antithrombin agent, argatroban, whereas the aggregation induced by Wilms' tumors was not suppressed by this agent. These results suggest that (1) malignant tumors in children also have some chemical substances that sensitize platelet activity, such as those in adult cancers, and (2) thrombin is one of the mediators stimulating platelet aggregation in cases of neuroblastoma, although it is unlikely to be a contributing factor in other pediatric malignancies such as Wilms' tumor.