Tanaka T, Saiki O, Doi S, Fuji M, Sugamura K, Hara H, Negoro S, Kishimoto S
Third Department of Internal Medicine, Osaka University, Japan.
J Immunol. 1988 Feb 1;140(3):866-70.
Novel IL-2-binding molecules (p70 and p75) mediating internalization and degradation of IL-2 were examined by employing a human B lymphoblastoid line, SKW6-4 cells. High concentrations of IL-2 induced IgM secretion in these cells through a receptor distinct from Tac antigen. The acid-wash technique revealed that more than 60% of 125I-labeled IL-2 bound to the cells became acid-unremovable in the first 30 min of incubation at 37 degrees C and degradation products of 125I-IL-2 increased after 30 min of incubation. Treatment of the cells with NaN3 buffer inhibited the appearance of acid-unremovable 125I-IL-2, suggesting that acid-unremovable 125I-IL-2 was not due to fluid-phase pinocytosis but due to internalization. Loss of labeled bands by incubation of cells with 125I-IL-2 at 37 degrees C before affinity cross-linking demonstrated that 125I-IL-2 was internalized via novel IL-2-binding molecules. These results suggest that novel IL-2-binding molecules are responsible for internalization and may mediate signal transduction in B cells in the absence of Tac antigen.
通过使用人B淋巴母细胞系SKW6-4细胞，研究了介导白细胞介素-2（IL-2）内化和降解的新型IL-2结合分子（p70和p75）。高浓度的IL-2通过一种不同于Tac抗原的受体诱导这些细胞分泌免疫球蛋白M（IgM）。酸洗技术显示，在37℃孵育的最初30分钟内，与细胞结合的超过60%的125I标记的IL-2变得不可酸洗，并且在孵育30分钟后125I-IL-2的降解产物增加。用叠氮化钠缓冲液处理细胞可抑制不可酸洗的125I-IL-2的出现，这表明不可酸洗的125I-IL-2不是由于液相胞饮作用，而是由于内化作用。在亲和交联之前，将细胞与125I-IL-2在37℃孵育导致标记条带消失，这表明125I-IL-2是通过新型IL-2结合分子内化的。这些结果表明，新型IL-2结合分子负责内化作用，并且在没有Tac抗原的情况下可能介导B细胞中的信号转导。
