PTPRC and myelodysplastic syndrome: While the frequency of committed progenitors and fully differentiated cells in the monocyte and granulocyte lineages were relatively reduced in low-risk MDS, higher-risk MDS samples exhibited abnormal immunophenotypic myeloid cells that resemble myeloid-derived-suppressor cells characterized by moderate expression of CD64, CD11b, CD44, CD45, CD45RA and lack of HLA-DR, CD14 and CD15 (51).