These colonies were referred to as ‘‘Type 1’’, ‘‘Type 2’’ and ‘‘Type 3’’ colonies. The total colony counts per petridish were 30–40 colonies,of which each of the colonies accounted for approximately 5–20%,30–35% and 40–60%. On the other hand, culture of the peripheral blood leukocytes under the same conditions revealed that no PMN cultures were produced and that only 0–2 colonies of Type 3 colony cells were generated from PBMC. Type 1 colonies were composed of numerous neutrophil-like cells and monocyte/macrophage-like cells,as well as a few megakaryocyte-like cells and eosinophil-like cells (Fig. 2D). Type 2 and 3 colonies primarily contained neutrophil-like cells with a few monocyte/macrophage-like cells and eosinophil-like cells (Fig. 2E and F)