Murine interleukin 7 (IL-7) receptor. Characterization on an IL-7-dependent cell line.

作者：Lina Seojin Park, Della J. Friend, Ann E. Schmierer, Steven Dower, Anthony E. Namen · 发表于：The Journal of Experimental Medicine · 年份：1990 · DOI：10.1084/jem.171.4.1073 · 被引用次数：149 · 研究领域：Monoclonal and Polyclonal Antibodies Research、Immune Cell Function and Interaction、Immune Response and Inflammation

A murine cell line (IxN/2b) absolutely dependent upon exogenous IL-7 for continued growth has been obtained that expresses lymphoid precursor and class I MHC antigens and also contains a rearranged mu heavy chain. This cell line has been used to define the binding and structural characteristics of the murine IL-7 receptor using 125I-labeled recombinant murine IL-7. 125I-IL-7 binding to IxN/2b cell was rapid and saturable at both 4 degrees and 37 degrees C. Equilibrium binding studies produced curvilinear Scatchard plots at both temperatures with high and low affinity Ka values of approximately 1 x 10(10) M-1 and 4 x 10(8) M-1, respectively, and a total of 2,000-2,500 IL-7 binding sites expressed per cell. Experiments measuring inhibition of binding of 125I-IL-7 by unlabeled IL-7 also produced data consistent with the existence of two classes of IL-7 receptors. Evidence concerning the possible molecular nature of two classes of IL-7 receptors was provided by dissociation kinetics and affinity crosslinking experiments. The dissociation rate of 125I-IL-7 was markedly increased when measured in the presence of unlabeled IL-7 at both 37 degrees and 4 degrees C, which is diagnostic of a receptor population displaying negative cooperativity. Crosslinking studies showed that under both reducing and nonreducing conditions, the major crosslinked species observed corresponded to a receptor size of 75-79 kD while a less intense higher molecular mass crosslinked species was also seen whic...