Dührsen U, Knieling G, Wu H X, Hossfeld D K
Abteilung für Onkologie und Hämatologie, Universitätskrankenhaus Eppendorf, Hamburg, Germany.
Blood. 1994 May 1;83(9):2627-36.
PGM-2 is a variant of the transplantable PGM-1 leukemia of strain C3H/HeJ. Freshly explanted cells had lymphoid morphology with a CD5+ CD45R (B220)- IgM- phenotype. They were not viable in unstimulated cultures, but formed IgM+ lymphoid colonies in response to interleukin-2 (IL-2), IL-4, IL-5, IL-6, IL-7, and Steel factor, and macrophage colonies in response to IL-3. IL-3-stimulated colonies had no recloning potential, but colonies from IL-7 cultures gave rise to large numbers of secondary macrophage colonies in IL-3-stimulated cultures and secondary lymphoid colonies in IL-7-stimulated cultures. The latter ones could be serially transferred in vitro for several months, and formed typical PGM-2 tumors in vivo. IL-7-stimulated colonies could therefore be used to measure leukemic stem cells in vitro. Supramaximal IL-3 stimulation (2,500 U/mL) of suspension cultures was followed by an increase in overall cell numbers and a disappearance of leukemic stem cells, compatible with differentiation induction. This could not be counteracted by simultaneous stimulation with IL-7. However, lower IL-3 concentrations (500 U/mL) induced an expansion of the stem cell pool, possibly by facilitating density-dependent autostimulatory mechanisms involving endogenous production of IL-7. The system described is a simple in vitro model for differentiation therapy. It shows that leukemic stem cells can be induced by hematopoietic growth factors to undergo terminal differentiation, but the concentrations required for differentiation induction in stem cells are much higher than those required for other biologic effects. Submaximal stimulation may favor expansion rather than repression of the leukemic cell population.
PGM-2是C3H/HeJ品系可移植性PGM-1白血病的一个变体。刚移植的细胞具有淋巴细胞形态，表型为CD5+ CD45R（B220）- IgM-。它们在未刺激的培养物中无法存活，但在白细胞介素-2（IL-2）、IL-4、IL-5、IL-6、IL-7和Steel因子的作用下可形成IgM+淋巴细胞集落，在IL-3的作用下可形成巨噬细胞集落。IL-3刺激的集落没有再克隆潜力，但IL-7培养物中的集落在IL-3刺激的培养物中可产生大量次级巨噬细胞集落，在IL-7刺激的培养物中可产生次级淋巴细胞集落。后者可在体外连续传代数月，并在体内形成典型的PGM-2肿瘤。因此，IL-7刺激的集落可用于体外测量白血病干细胞。悬浮培养物用超最大剂量的IL-3（2500 U/mL）刺激后，细胞总数增加，白血病干细胞消失，这与诱导分化相符。同时用IL-7刺激并不能抵消这种作用。然而，较低浓度的IL-3（500 U/mL）可诱导干细胞池扩大，可能是通过促进涉及内源性IL-7产生的密度依赖性自刺激机制。所描述的系统是一种用于分化治疗的简单体外模型。它表明造血生长因子可诱导白血病干细胞进行终末分化，但诱导干细胞分化所需的浓度远高于产生其他生物学效应所需的浓度。亚最大刺激可能有利于白血病细胞群体的扩增而非抑制。
