Re: the terminology issue for myeloid-derived suppressor cells.

With regard to the two recent letters (1, 2) proposing a name change from myeloid suppressor cells (MSC) to myeloid-derived suppressor cells (MDSC), although we appreciate the attempt to bring clarity to the cells responsible for immunosuppression, we do not think this alleviates the problem. In describing hematopoiesis, the terms myeloid and lymphoid simply discriminate between cells originating from the bone marrow and from lymph tissue, respectively, and myeloid encompasses both immature and mature cells. Thus, the term MDSC, in our opinion, does not help to convey that these are a heterogeneous mixture of myeloid cells at different stages of differentiation that are immunosuppressive. In fact, the term ‘‘myeloid-derived’’, if anything, suggests to us that the cells are more differentiated than the term ‘‘myeloid.’’ We would like to propose, instead, the term ‘‘myeloid immunosuppressive cells’’ (MIC) or ‘‘myeloid immune suppressor cells’’ (MISC). This removes the problem of MSCs being confused with mesenchymal stem cells and, more importantly, indicates that these cells suppress the immune system. Thus, we believe that MICs or MISCs more closely reflect the function of these cells than either MSCs or MDSCs and look forward to further thoughts from the immunology community on this subject.