Prevalence and prognostic significance of myeloid-derived suppressor cells and regulatory T cells in pancreatic and esophagogastric cancer

e21006 Background: Myeloid derived suppressor cell (MDSC) and regulatory T cell (Treg) accumulation in cancer patients is proposed as an important mechanism of tumor immune evasion. We present for the first-time analysis of both MDSCs and Tregs in pancreatic and esophago-gastric cancer. Methods: Peripheral blood samples were collected from 35 pancreatic, 46 esophageal and 19 gastric cancer patients and 31 normal healthy volunteers. PBMC was harvested and stored in liquid N2 with subsequent flow cytometric analysis of MDSC (HLADR- Lin1- CD33+ CD11b+) and Treg (CD4+ CD25+ CD127low/- FoxP3+). Unpaired T tests were applied to analyse MDSC and Treg levels between groups. Kaplan-Meier survival analysis was performed to compare patients with normal MDSC levels (as defined by the controls range, 0%-2% total PBMCs) and high MDSCs (> 2%). Results: The mean percentage of MDSCs in each cancer group was significantly higher than controls; pancreatic 2.455% (p = 0.0005), esophageal 1.623% (p = 0.0260) and gastric 2.029...