Effects of bone marrow fibroblastic cells and fibroblastic conditioned medium on HL-60 and KG-1

The in-vitro effects of bone marrow fibroblastic cells (FC) and fibroblastic conditioned medium (FCM) on the proliferation and differentiation of two human leukemic cell lines, HL-60 and KG-1 were studied. When FC were seeded onto only one-half of the culture dish an increase in colony size of HL-60 and KG-1 was observed directly above the FC. FCM had a greater effect, resulting in approximately a four-fold increase in the size of HL-60 and KG-1 colonies. In regards to colony number, FCM from normals inhibited HL-60, but FCM from other sources had no effect. FCM from both normals and ANLL in CR inhibited KG-1 colony number in contrast to the lack of effect with FCM from ANLL at diagnosis and RAEB. Neither FC nor FCM had any effect on the differentiation of either cell line. Our results indicate that FC modulate the proliferation of both HL-60 and KG-1. Furthermore, in ANLL the effects of FC are dependent upon the stage of the disease.