Characterization of mast cell-committed progenitors present in human umbilical cord blood

Human mast cells are derived from CD34(+) hematopoietic cells present in co rd blood, bone marrow, and peripheral blood. However, little is known about the properties of the CD34(+) cells. We demonstrated here that mast cell p rogenitors that have distinct phenotypes from other hematopoietic cell type s are present in cord blood by culturing single, sorted CD34(+) cells in 96 -well plates or unsorted cells in methylcellulose. The CD34(+) mast cell-co mmitted progenitors often expressed CD38 and often lacked HLA-DR, whereas C D34(+) erythroid progenitors often expressed both CD38 and HLA-DR and CD34( +) granulocyte-macrophage progenitors often had CD33 and sometimes expresse d CD38. We then cultured single cord blood-derived CD34(+)CD38(+) cells und er conditions optimal for mast cells and three types of myeloid cells, ie, basophils, eosinophils, end macrophages. Of 1,200 CD34(+)CD38(+) cells, we were able to detect 13 pure mast cell colonies and 52 pure colonies consist ing of either one of these three myeloid cell types. We found 17 colonies c onsisting of two of the three myeloid cell types, whereas only one colony c onsisted of mast cells and another cell type. These results indicate that h uman mast cells develop from progenitors that have unique phenotypes and th at committed mast cell progenitors develop from multipotent hematopoietic c ells through a pathway distinct from myeloid lineages including basophils, which have many similarities to mast cells, (C) 1999 by The American Societ y of Hematology.