Isolation and characterization of the erythroid progenitor cell: CFU-E.

Erythroid progenitor cells, CFU-E (colony-forming-unit-erythroid), were isolated to practical homogeneity by a combination of three enrichment procedures. CFU-E were generated in large amounts in spleens of mice previously bled and treated with the erythropoiesis-suppressing drug thiamphenicol. The average CFU-E concentration in spleens from mice 4 d after the thiamphenicol-treatment was 10%. These CFU-E were separated from lymphocytes, erythrocytes, and granulocytes and their progenitor cells by centrifugal elutriation and Percoll density gradient centrifugation. A three- to five-fold enrichment was obtained by elutriation, leading to a CFU-E concentration of 45%. With the Percoll gradient another twofold enrichment was achieved, providing us with a 80-100% CFU-E cell population. The overall recovery of CFU-E was 60-70%. This is a cheap, rapid, and highly efficient method of obtaining large quantities of viable CFU-E. The sequential formation of two-, four-, and eight-cell colonies from CFU-E cultured in vitro was studied. These cells enable us to study the biochemical changes occurring in the differentiation process of an erythroid progenitor cell induced by the hormone erythropoietin. The morphological and some physical and biological properties of these cells are presented.