Blackard W G, Sherrod J, Ludeman C
Endocrinology. 1981 Feb;108(2):478-83. doi: 10.1210/endo-108-2-478.
The extraction of insulin receptor antibody (ARAB) by IM-9 lymphoblastoid cells was measured using nonisotopic ARAB, ARAB extraction was expressed as a clearance, with ARAB determinations made indirectly by a method dependent on its inhibition of insulin binding. Control cells and down-regulated IM-9 cells (cells exposed to 10(-7) M insulin for 16 h) at a cell density of 8 X 10(7) cells/ml were incubated in the presence of a 1:75 dilution of serum from a patient with insulin resistance due to insulin receptor antibodies. After 60 min at room temperature, control cells cleared 42 +/- 3% of ARAB compared to only 18 +/- 2% by the down-regulated cells. ARAB clearance was directly proportional to maximal tracer insulin binding, as determined in parallel experiments. ARAB clearance was similarly reduced in a dose-related fashion by 16-h exposure to Concanavalin A. These results indicate that ARAB extraction by IM-9 cells is reduced by chronic exposure to insulin. The observation that ARAB binding to insulin down-regulated cells is reduced despite the ability of ARAB to attach normally to cells whose receptors have been saturated with insulin supports the notion that down-regulation is due to a loss of membrane receptor rather than to simple receptor occupancy. (Endocrinology 108: 478, 1981)
采用非同位素胰岛素受体抗体（ARAB）测定IM-9淋巴母细胞样细胞对ARAB的提取情况，ARAB提取以清除率表示，通过一种依赖其对胰岛素结合抑制作用的方法间接测定ARAB。将细胞密度为8×10⁷个细胞/毫升的对照细胞和下调的IM-9细胞（暴露于10⁻⁷M胰岛素16小时的细胞）与一名因胰岛素受体抗体导致胰岛素抵抗患者的血清按1:75稀释后一起孵育。在室温下孵育60分钟后，对照细胞清除了42±3%的ARAB，而下调的细胞仅清除了18±2%。如平行实验所确定的，ARAB清除率与最大示踪胰岛素结合直接相关。通过16小时暴露于伴刀豆球蛋白A，ARAB清除率同样以剂量相关方式降低。这些结果表明，长期暴露于胰岛素会降低IM-9细胞对ARAB的提取。尽管ARAB能够正常附着于其受体已被胰岛素饱和的细胞，但ARAB与胰岛素下调细胞的结合减少，这一观察结果支持下调是由于膜受体丢失而非简单的受体占据这一观点。（《内分泌学》108:478,1981）
