Myeloid-Derived Suppressor Cells In Patients With Hodgkin Lymphoma.

Abstract Abstract 3662 Poster Board III-598 Background Immune suppression and angiogenesis are mechanisms key to tumour growth and progression. Myeloid-derived suppressor cells (MDSC) are a heterogeneous population of cells of myeloid origin and include immature macrophages, dendritic cells (DC) and other myeloid cells. In mice are phenotypically characterized as CD11b+Gr-1+ cells, while in human they have an immature phenotype, including lineage negative (Lin-), CD14-, HLA-DR-, CD15+, CD34+, CD11b+, CD33+, and CD13+ cells. MDSC reduce activated T-cell number and inhibit their function through different mechanisms including: L-arginine metabolism, nitric oxide (NO), up-regulation of reactive oxygen species (ROS), and secretion of immunosuppressive cytokines. MDSC also promote tumor-dependent angiogenesis as well as tumor metastasis. Their accumulation has been described in patients affected by some solid tumors but information on haematological neoplasms are lacking. Our study investigated by flow cytometry the presence of MSDC in the peripheral blood of patients affected by Hodgkin Lymphoma (HL). Methods We studied 14 patients with HL at diagnosis and 10 age-matched healthy controls (HC). Peripheral blood mononuclear cells were stained with the following monoclonal antibodies:CD11b, CD13, CD14, CD34, CD45, for 20 minutes at room temperature. After lysing red cells, cells were analyzed by flow cytometry. Results we observed a increased number of MDSC (CD11b+,CD13+,CD34+,CD14-, CD45+) in the peripheral blood of patients with HL compared to HC (13,37 ± 17,77 ×109/l vs 1,45± 0,98 ×109/l, p=0,0007). We also found that patients with advanced-stage Hodgkin disease (III and IV) have higher number of MDSC, compared to patients stage I and II (p= 0,04). Conclusion These data suggest a role for myeloid-derived suppressor cells in promoting tumor cell proliferation in hodgkin lymphoma. Disclosures: No relevant conflicts of interest to declare.