Usefulness of peripheral regulatory T-cells induced by Notch signaling pathway-driven indoleamine 2, 3-dioxygenase positive dendritic cell as a biomarker for the decision for IPMN surgical indications.

181 Background: This study was performed to elucidate the expression of the Notch signaling pathway regulated by dendetric cell (DC) and their correlations to clinicopathological factors of intraductal papillary mucinous neoplasms (IPMNs) as a new biomarker for surgical indications. We already reported that regulatory T cells (Tregs) play an important role in tumor immunity (Pancreas 2006, ASCO-GI 2009), however, the whole mechanism of control of peripheral Tregs remains unclear. It is reported that Indoleamine 2, 3-dioxygenase (IDO) induces active Treg from naive CD4+Tcells through dendritic cells. Otherwise, we also reported that the Notch signaling pathway is involved in tumor growth and DC function (JI 2010). Thus we focused that Indoleamine 2,3-deoxygenase(IDO)-Treg axis driven by Notch signaling in IPMNs. Methods: Peripheral blood samples and resected specimens from 20 patients with IPMN were evaluated. All patients were pathologically diagnosed with IPMN. Resected specimens were immunohistochemical...