Montel A H, Bochan M R, Hobbs J A, Lynch D H, Brahmi Z
Department of Microbiology/Immunology, Indiana University School of Medicine, Indianapolis 46202-5200, USA.
Cell Immunol. 1995 Dec;166(2):236-46. doi: 10.1006/cimm.1995.9974.
Lysis of target cells (TC) by cytolytic lymphocytes involves the secretion of cytoplasmic granules containing perforin and serine esterases by the effector cell (EC). Recently, a granule-independent cytolytic mechanism involving the interaction of the apoptosis-triggering Fas antigen (CD95) with Fas ligand (FasL) has been revealed in T cells. However, whether the Fas lytic pathway also functions in NK cells has not been established. We purified human peripheral NK cells (> 98% CD56+) and found that PMA and ionomycin treatment upregulated FasL message and stimulated the NK cells to lyse a Fas+ TC. This lysis was partially inhibited by the anti-Fas-blocking antibody M3 or by Fas.Fc fusion protein. We also found that FasL is constitutively expressed on the human NK-like leukemia cell line YT-INDY and that YT-INDY utilizes a Ca(2+)-independent Fas lytic pathway, as well as the granule pathway. We have previously shown that CD28/B7 interactions are involved in TC recognition by YT-INDY. K562 cotransfected with Fas and B7-1 (K562/Fas/B7) was lysed by YT-INDY at a higher level than a vector-transfected K562 line, whereas K562 transfected with Fas alone was not. Lysis of K562/Fas/B7 cotransfectants was partially Fas-mediated, as indicated by the presence of Ca(2+)-independent, M3-inhibitable lysis. Ca(2+)-independent, Fas-mediated lysis of several TC by YT-INDY was inhibited by anti-CD28 antibody. Anti-LFA-1 also inhibited Fas-mediated cytotoxicity in YT-INDY. Thus, fresh human NK cells and the human NK-like cell line YT-INDY are capable of using the Fas lytic pathway. In YT-INDY, CD28/B7 and LFA-1/ICAM interactions appear to influence the Fas lytic pathway.
细胞毒性淋巴细胞对靶细胞（TC）的裂解作用涉及效应细胞（EC）分泌含有穿孔素和丝氨酸酯酶的细胞质颗粒。最近，在T细胞中发现了一种不依赖颗粒的细胞毒性机制，该机制涉及凋亡触发因子Fas抗原（CD95）与Fas配体（FasL）的相互作用。然而，Fas裂解途径在NK细胞中是否也起作用尚未明确。我们纯化了人外周血NK细胞（>98% CD56+），发现佛波酯（PMA）和离子霉素处理可上调FasL的表达，并刺激NK细胞裂解Fas+靶细胞。这种裂解作用部分被抗Fas阻断抗体M3或Fas.Fc融合蛋白所抑制。我们还发现FasL在人NK样白血病细胞系YT-INDY中组成性表达，并且YT-INDY利用不依赖Ca(2+)的Fas裂解途径以及颗粒途径。我们之前已经表明CD28/B7相互作用参与YT-INDY对靶细胞的识别。与Fas和B7-1共转染的K562（K562/Fas/B7）比载体转染的K562细胞系更容易被YT-INDY裂解，而单独转染Fas的K562细胞则不然。K562/Fas/B7共转染细胞的裂解部分是由Fas介导的，这表现为存在不依赖Ca(2+)、可被M3抑制的裂解作用。抗CD28抗体可抑制YT-INDY对几种靶细胞的不依赖Ca(2+)、Fas介导的裂解作用。抗LFA-1抗体也可抑制YT-INDY中Fas介导的细胞毒性作用。因此，新鲜的人NK细胞和人NK样细胞系YT-INDY能够利用Fas裂解途径。在YT-INDY中，CD28/B7和LFA-1/ICAM相互作用似乎会影响Fas裂解途径。
