Bonavida B, Lebow L T, Bradley T P
J Immunol. 1984 Feb;132(2):594-8.
Single cell cytotoxicity assays reveal that a large percentage of lymphocytes are unable to kill attached targets in a 4- to 18-hr assay. Additional signals (in the form of lectin or anti-target antibody) delivered to target-bound lymphocytes enable these previously non-lytic lymphocytes to kill attached target cells. This finding was obtained by using a modification of the single cell assay, in which lectin or target cell antibody is incorporated into agarose with preformed lymphocyte-target conjugates. Human peripheral blood lymphocytes (PBL) or Percoll density gradient-enriched large granular lymphocytes (LGL) were used as effector cells in natural killer (NK), antibody-dependent cellular cytotoxicity (LDCC) assay systems. The targets used were NK-sensitive K562 and Molt-4 and NK-insensitive Raji. Several findings were made in the modified single cell assay, namely a) the frequency of cytotoxic NK or ADCC effector cells was not augmented, suggesting that the initial trigger was sufficient for lytic expression in these instances. Furthermore, these results showed that the NK-sensitive targets used do not bind nonspecifically to the LDCC effector cells. K562 coated with Con A, however, serve as LDCC targets. b) The frequency of two target conjugate lysis by NK/K effectors was not augmented by Con A. These results suggest that Con A does not potentiate the killing of multiple targets bound to a single cytotoxic lymphocyte. c) Although conjugates formed between LGL or PBL and NK-insensitive Raji are non-lethal, significant lysis was observed when these conjugates were suspended in Con A or antibody agarose. These results demonstrate that Raji bind to cytotoxic NK, K, and LDCC effector cells, but are lysed only when the appropriate trigger is provided. d) The cytotoxic potential of non-lytic conjugates appears to lie within the low density Percoll fraction, although the high density lymphocytes are able to nonlethally bind to targets. Altogether the results demonstrate that target recognition and/or binding by the effector cells is a distinct event from the trigger or lytic process. The implications of these findings are discussed.
单细胞细胞毒性试验表明，在4至18小时的试验中，很大比例的淋巴细胞无法杀死附着的靶细胞。传递给与靶细胞结合的淋巴细胞的额外信号（以凝集素或抗靶抗体的形式）能使这些先前无细胞溶解作用的淋巴细胞杀死附着的靶细胞。这一发现是通过对单细胞试验进行改进获得的，即将凝集素或靶细胞抗体与预先形成的淋巴细胞 - 靶细胞结合物一起掺入琼脂糖中。人外周血淋巴细胞（PBL）或经Percoll密度梯度富集的大颗粒淋巴细胞（LGL）在自然杀伤（NK）、抗体依赖性细胞毒性（LDCC）试验系统中用作效应细胞。所使用的靶细胞是对NK敏感的K562和Molt - 4以及对NK不敏感的Raji。在改进的单细胞试验中有几个发现，即：a）细胞毒性NK或ADCC效应细胞的频率没有增加，这表明在这些情况下初始触发足以实现溶解表达。此外，这些结果表明所使用的对NK敏感的靶细胞不会非特异性地结合到LDCC效应细胞上。然而，用刀豆球蛋白A（Con A）包被的K562可作为LDCC靶细胞。b）Con A不会增加NK/K效应细胞对两个靶细胞结合物的溶解频率。这些结果表明Con A不会增强对与单个细胞毒性淋巴细胞结合的多个靶细胞的杀伤作用。c）虽然LGL或PBL与对NK不敏感的Raji形成的结合物是无致死性的，但当这些结合物悬浮在Con A或抗体琼脂糖中时会观察到明显的溶解。这些结果表明Raji能结合细胞毒性NK、K和LDCC效应细胞，但只有在提供适当触发信号时才会被溶解。d）非溶解结合物的细胞毒性潜力似乎存在于低密度Percoll组分中，尽管高密度淋巴细胞能够与靶细胞进行非致死性结合。总之，结果表明效应细胞对靶细胞的识别和/或结合与触发或溶解过程是不同的事件。讨论了这些发现的意义。
