Human peripheral blood "null-lymphocytes", a highly enriched pool for granulocytic stem cells (CFU-C).

A "Null"-lymphocyte preparation containing a high concentration of granulocytic stem cells (CFU-C) was isolated from human peripheral blood. 3 lymphocyte purification procedures were shown to produce an enrichment of CFU-C: 1. Removal of mononuclear phagocytes by iron phagocytosis and plastic adherence procedures. 2. Passage through Ig anti-Ig columns. 3. Removal of E-rosette-forming T cells. A combination of all 3 purification steps resulted in a 30- to 40-fold enrichment of CFU-C in the final "Null"-lymphocyte population as compared to the initial lymphocyte fraction isolated by Ficoll-Urografin density gradient centrifugation.