A method for obtaining human bone marrow specimens enriched for myeloblasts and promyelocytes.

A simple method has been developed for obtaining specimens of human marrow which are enriched for myeloblasts and promyelocytes. The erythrocytes are lysed, the marrow is incubated with iron particles, and the cells that phagocytize the iron are removed with a powerful magnet. The marrow is then subjected to a density-cut centrifugation using Ficol-Hypaque with a density of 1.084 gm/mm3. The cells that do not enter the Ficol-Hypaque are removed from the surface and studied. The proportion of myeloblasts and promyelocytes in this subpopulation of cells exceeds 50%. Total recovery of these immature myeloid progenitor cells is 50% of that in the original marrow specimen. This method has been used for cell suspensions containing as many as 10(9) cells. Cells prepared using this method incorporate 3H-TdR, 3H-UR, and 3H-Leu at a higher rate than the unseparated specimens and have a cloning efficiency of 2.0% to 19.4% compared with 0.1% to 2.17% for the unseparated marrows.