IDENTIFICATION AND CHARACTERIZATION OF CANDIDATE MYELOID DERIVED SUP- PRESSOR CELLS IN THE MONONUCLEAR FRACTION OF PERIPHERAL BLOOD SAMPLES FROM PATIENTS AFFECTED BY NON-HODGKIN LYMPHOMA (NHL), HODGKIN LYMPHOMA (HL), AND MULTIPLE MYELOMA (MM)

Myeloid derived suppressor cells (MDSCs) constitute a heterogeneous population of myeloid cells characterized by the ability to suppress T lymphocytes’ immune responses. MDSC include two major subsets (i.e. monocytic and granulocytic), defined by the expression of distinctive antigens (CD11b+CD14+HLA-DRlow/ and CD11b+CD33+CD15+), and by the content of specific immune suppressive molecules. Current- ly, a large number of MDSC phenotypes have been described in differ- ent human diseases, including solid tumors, infections and inflammato- ry diseases. However, the existence of MDSCs in human hematologi- cal malignancies remains debated and to date myeloid CD11b+CD14+HLA-DRlow/ or CD11b+CD33+CD15+ cell popula- tions with putative immunosuppressive functions have been described by two studies only conducted respectively in a NHL and in a MM series. Aim of our study was to identify candidate MDSCs in the periph- eral blood mononuclear fraction (PBMC) of peripheral blood samples obtained from patients affected by NHL, HL and MM.