Fc receptors of a human promyelocytic leukemic cell line: evidence for two types of receptors defined by binding of the staphylococcal protein A-IgG1 complex.
Fc receptors of a human promyelocytic leukemic cell line: evidence for two types of receptors defined by binding of the staphylococcal protein A-IgG1 complex.
复制标题
人类早幼粒细胞白血病细胞系的 Fc 受体：通过葡萄球菌蛋白 A-IgG1 复合物的结合定义的两种类型受体的证据。
作者：
G. Crabtree
在人早幼粒细胞系（HL-60）中研究了纯化的单体人和小鼠骨髓瘤免疫球蛋白与Fc受体结合的特异性和动力学。HL-60细胞每个细胞含有约20，000个Fc受体，并以高亲和力（解离常数为5 - 10 nM）结合人IgG1、IgG3和小鼠IgG2a。IgG1与HL-60细胞结合的动力学研究表明，在37 ℃下，每25至30分钟约有一半的表面结合IgG1与周围免疫球蛋白发生快速交换。估计的平衡结合常数从协会和解离的IgG 1的速率一致，以及从Scatchard分析放射性碘标记的IgG 1的平衡结合得到的值。HL-60细胞中约一半的Fc受体能够结合与蛋白A复合的IgG 1。该结果与蛋白A的浓度（0.5至200 μ M）或IgG 1与蛋白A的孵育时间无关。将蛋白A与HL-60细胞在37 ℃孵育，然后在0 ℃快速洗涤的研究表明，蛋白A不降解Fc受体或与HL-60细胞上的Fc受体位点相互作用。蛋白A和IgG 1之间形成的复合物通过超离心沉淀在7 - 9S处。这些结果表明HL-60细胞上存在两种类型的Fc受体，其可通过其结合IgG 1-蛋白A复合物的能力来区分。
The specificity and kinetics of binding of purified monomeric human and murine myeloma immunoglobulins to Fc receptors were studied in a human promyelocytic cell line (HL-60). HL-60 cells contain approximately 20,000 Fc receptors per cell and bind human IgG1, IgG3 and mouse IgG2a with high affinity (dissociation constant of 5 to 10 nM). Kinetic studies of the binding of IgG1 to HL-60 cells demonstrate rapid exchange with ambient immunoglobulin with approximately one-half of the surface-bound IgG1 exchanging every 25 to 30 min at 37 degrees C. Estimation of the equilibrium binding constant from the rates of association and dissociation of IgG1 agrees well with the values obtained from Scatchard analysis of equilibrium binding of radioiodinated IgG1. Approximately one-half of the Fc receptors of HL-60 cells are capable of binding IgG1 complexed to Protein A. This result was independent of the concentration of Protein A (0.5 to 200 microM) or the time of incubation of IgG1 with Protein A. Studies in which Protein A was incubated with HL-60 cells at 37 degrees C then rapidly washed at 0 degrees C indicated that Protein A did not degrade Fc receptors or interact with the Fc receptor sites on HL-60 cells. The complexes formed between Protein A and IgG1 sedimented at 7 to 9S by ultracentrifugation. These results suggest that there are two types of Fc receptors on HL-60 cells, which can be distinguished by their ability to bind the IgG1-Protein A complex.