Budel L M, Elbaz O, Hoogerbrugge H, Delwel R, Mahmoud L A, Löwenberg B, Touw I P
Dr Daniel den Hoed Cancer Center, Rotterdam, The Netherlands.
Blood. 1990 Apr 1;75(7):1439-45.
Granulocyte macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) control the proliferation of human acute myeloid leukemia (AML) cells in vitro. Previously, we have shown that receptors for GM-CSF and IL-3 are often coexpressed on AML cells. Here we present experiments with purified AML blasts, normal monocytes, and granulocytes that were conducted to analyze the properties of GM-CSF and IL-3 binding proteins in more detail. On AML cells from eight cases we demonstrate two types of GM-CSF receptors: one with low affinity (dissociation constant [kd] 5.1 to 24.8 nmol/L) and one with a high affinity (kd 31 to 104 pmol/L). These AML cells also expressed high affinity receptors for IL-3 (kd 24 to 104 pmol/L). Cross-competition experiments showed that an excess concentration of nonlabeled IL-3 completely prevented the high affinity binding of radiolabled GM-CSF. This competition occurred at 37 degrees C as well as 4 degrees C. Low affinity GM-CSF binding was not affected by IL-3. Binding of radiolabeled IL-3 could be prevented by nonlabeled GM-CSF. In certain cases, this competition was complete, whereas in others only partial (49% to 77%) reduction of the radiolabeled IL-3 binding was seen. On the basis of these ligand binding features, we propose the existence of three receptor types on AML cells: (1) low affinity GM-CSF receptors that do not bind IL-3, (2) dual high affinity GM-CSF/IL-3 receptors, and (3) high affinity IL-3 receptors that do not bind GM-CSF. We could also demonstrate these receptor types on normal monocytes. In addition, a fourth type of receptor was apparent on normal granulocytes (4), incapable of binding IL-3 and with an intermediate affinity for GM-CSF (approximately 400 pmol/L). Chemical crosslinking showed that GM-CSF and IL-3 both bind to proteins with molecular weight values of 130, 105, and 75, which provides additional evidence for the existence of a common GM-CSF/IL-3 receptor complex.
粒细胞巨噬细胞集落刺激因子（GM-CSF）和白细胞介素-3（IL-3）在体外可控制人急性髓性白血病（AML）细胞的增殖。此前，我们已表明GM-CSF和IL-3的受体常在AML细胞上共表达。在此，我们展示了用纯化的AML原始细胞、正常单核细胞和粒细胞进行的实验，这些实验旨在更详细地分析GM-CSF和IL-3结合蛋白的特性。在来自8例患者的AML细胞上，我们证实了两种类型的GM-CSF受体：一种具有低亲和力（解离常数[kd]为5.1至24.8 nmol/L），另一种具有高亲和力（kd为31至104 pmol/L）。这些AML细胞还表达了对IL-3的高亲和力受体（kd为24至104 pmol/L）。交叉竞争实验表明，过量的未标记IL-3完全阻止了放射性标记的GM-CSF的高亲和力结合。这种竞争在37℃以及4℃时均会发生。低亲和力的GM-CSF结合不受IL-3影响。放射性标记的IL-3的结合可被未标记的GM-CSF阻止。在某些情况下，这种竞争是完全的，而在其他情况下，仅观察到放射性标记的IL-3结合减少了部分（49%至77%）。基于这些配体结合特征，我们提出AML细胞上存在三种受体类型：（1）不结合IL-3的低亲和力GM-CSF受体，（2）双高亲和力GM-CSF/IL-3受体，以及（3）不结合GM-CSF的高亲和力IL-3受体。我们还能在正常单核细胞上证实这些受体类型。此外，在正常粒细胞上明显存在第四种受体类型（4），它不能结合IL-3，对GM-CSF具有中等亲和力（约400 pmol/L）。化学交联表明，GM-CSF和IL-3均与分子量为130、105和75的蛋白质结合，这为共同存在的GM-CSF/IL-3受体复合物的存在提供了额外证据。
