Lowenthal J W, Corthésy P, Tougne C, Lees R, MacDonald H R, Nabholz M
J Immunol. 1985 Dec;135(6):3988-94.
In this report we characterize two classes of interleukin 2 (IL 2) binding sites on the basis of their differential IL 2 dissociation rate and of their reactivity with PC61, a monoclonal anti-IL 2 receptor (IL 2-R) antibody. PC61 inhibited the binding of IL 2 to both classes of receptor, but IL 2 did not inhibit the binding of PC61. This indicates that PC61 recognizes a determinant that is distal to the actual IL 2 binding site of the receptor. Dissociation experiments showed that the addition of excess unlabeled IL 2 resulted in a biphasic release of radiolabeled IL 2; 80 to 90% was dissociated rapidly (dissociation half-time, t1/2 of 60 sec) and the remainder more slowly (t1/2 60 to 90 min). The proportion of high and low affinity IL 2-R, as well as the relative difference in dissociation rates fit very well with the estimates derived previously from Scatchard plot analysis of equilibrium IL 2 binding. The addition of PC61 caused an accelerated dissociation of IL 2 from both high and low affinity IL 2-R (t1/2 of 16 and 120 sec respectively).
在本报告中，我们根据白细胞介素2（IL-2）的不同解离速率及其与单克隆抗IL-2受体（IL-2-R）抗体PC61的反应性，对两类IL-2结合位点进行了表征。PC61抑制IL-2与两类受体的结合，但IL-2不抑制PC61的结合。这表明PC61识别的决定簇位于受体实际IL-2结合位点的远端。解离实验表明，加入过量未标记的IL-2会导致放射性标记的IL-2呈双相释放；80%至90%迅速解离（解离半衰期t1/2为60秒），其余部分解离较慢（t1/2为60至90分钟）。高亲和力和低亲和力IL-2-R的比例以及解离速率的相对差异与先前通过平衡IL-2结合的Scatchard图分析得出的估计值非常吻合。加入PC61会导致IL-2从高亲和力和低亲和力IL-2-R上加速解离（分别为t1/2为16秒和120秒）。
