Target cell expression of MHC antigens is not (always) a turn-off signal to natural killer cells.
Target cell expression of MHC antigens is not (always) a turn-off signal to natural killer cells.
复制标题
MHC 抗原的靶细胞表达并不（始终）是自然杀伤细胞的关闭信号。
作者：
R. Chervenak;R. Wolcott
最近的证据表明，自然杀伤细胞的裂解功能可能是由潜在的靶细胞通过靶细胞表达能够抑制裂解过程的细胞表面成分来调节的。具体地，在许多靶细胞系统中已经显示，靶细胞对I类MHC蛋白的表达与它们对NK细胞裂解的易感性成反比。因此，有人建议，MHC蛋白可能作为重要的负调控元件，在持续控制NK细胞的功能。在此，我们研究了两个密切相关的小鼠淋巴瘤细胞（ASL 1和ASL 1 w），无论是在其对NK细胞裂解的敏感性，以及它们的H-2K和H-2D I类MHC蛋白的表达。这些研究的结果表明，尽管ASL 1和ASL 1 w细胞对NK细胞裂解的敏感性差异很大（ASL 1比ASL 1 w更具NK抗性），但两者都表达高水平的H-2K和D蛋白。与根据其他靶细胞系统的报告可能预测的结果相反，NK敏感性更高的ASL 1 w细胞表达的H-2K Ag水平略高于ASL 1细胞。这些结果表明靶细胞表达H-2 I类蛋白本身不足以抑制鼠NK细胞的裂解活性。
Recent evidence has demonstrated that the lytic function of natural killer cells might be regulated by potential target cells through the target cells' expression of cell surface components that are able to inhibit the lytic process. Specifically, it has been shown in many target cell systems that the expression of class I MHC proteins by target cells is inversely proportional to their susceptibility to lysis by NK cells. It has been suggested, therefore, that MHC proteins may act as important negative regulatory elements in the ongoing control of NK cell function. Herein, we examined two closely related murine lymphoma cells (ASL1 and ASL1w), both in terms of their susceptibility to lysis by NK cells as well as their expression of both H-2K and H-2D class I MHC proteins. The results of these studies showed that whereas ASL1 and ASL1w cells differed greatly in their susceptibility to NK cell lysis (ASL1 was much more NK resistant than ASL1w), both expressed high levels of H-2K and D proteins. In contrast to what might have been predicted base on reports from other target cell systems, the more NK susceptible ASL1w cells expressed somewhat higher levels of H-2K Ag than did ASL1 cells. These results indicate that expression of H-2 class I proteins by target cells, in and of itself, is not sufficient to inhibit the lytic activity of murine NK cells.