Yonehara S, Ishii A, Yonehara-Takahashi M
J Gen Virol. 1983 Nov;64 (Pt 11):2409-18. doi: 10.1099/0022-1317-64-11-2409.
The binding of [3H]leucine-labelled pure human interferon alpha from Namalwa cells to human FL and Daudi cells was studied, and evidence obtained to indicate receptor-mediated internalization of interferon. Cell surface-bound and internalized interferons were quantified separately as trypsin-released and unreleased radioactivities, respectively. At 37 degrees C, surface-bound interferon reached a maximum after 1 h and then decreased, while internalized interferon reached a maximum after 2 h. At 21 degrees C, in contrast, surface-bound interferon reached a maximum after 2 h and did not decrease thereafter; no internalization was observed. The same was true at 37 degrees C in the presence of NaF, indicating dependence of internalization on temperature and energy. In control cultures at 37 degrees C, internalized interferon, after reaching a maximum, decreased after prolonged incubation, and concomitantly acid-soluble radioactivity appeared in the culture medium. The decrease in internalized interferon and the emergence of degraded interferon were inhibited by the lysosomotropic agents, ammonium chloride and chloroquine. The fate of labelled interferon, bound to the cell surface of FL cells at 21 degrees C was studied at 37 degrees C, and the results indicated that trypsin-unreleased interferon was derived from the surface-bound interferon, and was secreted in part into the culture fluid in a degraded form upon prolonged incubation. The relation of internalization of interferon to its biological activity was studied in three ways. In FL cells, the antiviral activity was not induced when internalization of interferon was entirely blocked (at 21 degrees C or in the presence of NaF at 37 degrees C). In Daudi cells, both 2'-5'-oligoadenylate (2-5A) synthetase induction by interferon and internalization of interferon were inhibited completely by diethyldithiocarbamate (DDC), whereas in the case of FL cells, DDC inhibited neither 2-5A synthetase induction nor internalization of interferon. Raji cells, which have an interferon-specific binding site on the cell surface but are insensitive to interferon, were found not to internalize interferon, whereas other Burkitt's lymphoma cells, Daudi and Namalwa, which are sensitive to interferon, did internalize it. These findings suggest (but do not prove) that internalization is required for the establishment of interferon activity.
研究了[³H]亮氨酸标记的来自Namalwa细胞的纯人α干扰素与人类FL细胞和Daudi细胞的结合情况，并获得证据表明干扰素存在受体介导的内化作用。分别将细胞表面结合的和内化的干扰素定量为胰蛋白酶释放的和未释放的放射性活性。在37℃时，表面结合的干扰素在1小时后达到最大值，然后下降，而内化的干扰素在2小时后达到最大值。相比之下，在21℃时，表面结合的干扰素在2小时后达到最大值，此后不再下降；未观察到内化现象。在37℃存在NaF的情况下也是如此，这表明内化作用依赖于温度和能量。在37℃的对照培养物中，内化的干扰素在达到最大值后，长时间孵育后会下降，同时培养基中会出现酸溶性放射性活性。溶酶体促渗剂氯化铵和氯喹可抑制内化干扰素的减少和降解干扰素的出现。研究了在21℃结合于FL细胞表面的标记干扰素在37℃时的命运，结果表明胰蛋白酶未释放的干扰素源自表面结合的干扰素，长时间孵育后部分以降解形式分泌到培养液中。从三个方面研究了干扰素内化与其生物学活性的关系。在FL细胞中，当干扰素的内化完全被阻断时（在21℃或在37℃存在NaF的情况下），不会诱导抗病毒活性。在Daudi细胞中，二乙基二硫代氨基甲酸盐（DDC）完全抑制了干扰素诱导的2'-5'-寡腺苷酸（2-5A）合成酶以及干扰素的内化，而在FL细胞中，DDC既不抑制2-5A合成酶的诱导也不抑制干扰素的内化。发现细胞表面有干扰素特异性结合位点但对干扰素不敏感的Raji细胞不会内化干扰素，而其他对干扰素敏感的伯基特淋巴瘤细胞Daudi和Namalwa则会内化干扰素。这些发现提示（但未证明）内化对于干扰素活性的建立是必需的。
