Clonal analysis of the response of HL60 human myeloid leukemia cells to biological regulators

Abstract

Human myeloid leukemia (HL60) cells formed colonies in semi-solid agar cultures with a cloning efficiency of 20–90%. Addition of unfractionated human placental conditioned medium (HPCM) or the two semi-purified granulocyte-macrophage colony stimulating factors from HPCM (GM-CSFα and β) increased colony size and the frequency of colonies exhibiting differentiation of colony cells. Differentiation induction using GM-CSFα or β did not reduce the total number of clonogenic cells per colony but did reduce the proportion of clonogenic cells within colonies. Sera from some patients with acute infections exhibited an elevated capacity to induce differentiation both in HL60 colonies and in colonies of the mouse myelomonocytic leukemia cell line, WEHI-3B. A low percentage of HL60 colonies contained maturing eosinophils but the frequency was not influenced by human-active eosinophil colony stimulating factors or by sequential recloning of HL60 colonies. The studies suggest that, as is true for mouse myeloid leukemia cell lines, the granulocyte-macrophage colony stimulating factors are able to induce significant differentiation in human HL60 myeloid leukemia cells.