Brutkiewicz R R, Klaus S J, Welsh R M
Department of Pathology, University of Massachusetts Medical Center, Worcester 01655.
Nat Immun. 1992 Jul-Aug;11(4):203-14.
A time course study was performed in order to determine if vaccinia virus (VV)-infected targets were more susceptible to murine natural killer (NK) cell-mediated lysis during a discrete period of time postinfection. Activated NK cells were used in short-term (e.g. 4 h) assays in order to avoid a further in vitro activation of the NK cells by interferon (IFN) and to test the innate susceptibility of target cells to lysis. The sensitivity of VV-infected L929 cells to lysis by NK cells increased as the infection progressed, reached a peak at approximately 24 h postinfection, and subsequently declined to levels lower than that of uninfected cells. This window of vulnerability was not due to an increase in the number of effector/target cell conjugates, which continually decreased as the VV infection progressed. Triggering of NK cells was measured by the influx of 45Ca2+. Target cells treated with IFN induced less 45Ca2+ uptake, whereas cycloheximide treatment of targets caused a greater influx of 45Ca2+ into the effector cells. When L929 cells were infected with VV for various time intervals and used in the triggering assays, an enhanced triggering of the effectors corresponding to the time of enhanced susceptibility of the target cells to lysis was detected. Quantitative decreases in H-2Kk and Dk class I antigens were observed following VV infection of target cells as measured by FACS analysis using alloantibodies. Qualitative changes in H-2 class I antigens were also observed, as detected by a loss in VV-infected target cell susceptibility to lysis by allospecific cytotoxic T lymphocytes (CTL) at a time when they were highly sensitive to killing by NK cells and VV-specific CTL. These results show that virus-infected targets may become innately more sensitive to lysis by NK cells at discrete time points after infection and that the susceptibility to lysis correlates with enhanced triggering of NK cells and reduced H-2 class I antigen expression.
进行了一项时间进程研究，以确定痘苗病毒（VV）感染的靶细胞在感染后的一段特定时间内是否更易被小鼠自然杀伤（NK）细胞介导的裂解作用所影响。使用活化的NK细胞进行短期（如4小时）检测，以避免NK细胞被干扰素（IFN）进一步体外激活，并测试靶细胞对裂解作用的固有敏感性。随着感染的进展，VV感染的L929细胞对NK细胞裂解的敏感性增加，在感染后约24小时达到峰值，随后下降至低于未感染细胞的水平。这种易损窗口并非由于效应细胞/靶细胞结合物数量的增加，随着VV感染的进展，其数量持续减少。通过45Ca2+的流入来测量NK细胞的激活。用IFN处理的靶细胞诱导的45Ca2+摄取较少，而用环己酰亚胺处理靶细胞会导致更多的45Ca2+流入效应细胞。当L929细胞用VV感染不同时间间隔并用于激活检测时，检测到与靶细胞对裂解作用敏感性增强的时间相对应的效应细胞激活增强。通过使用同种抗体的FACS分析测量，在靶细胞被VV感染后观察到H-2Kk和Dk I类抗原的定量减少。还观察到H-2 I类抗原的定性变化，表现为在VV感染的靶细胞对同种特异性细胞毒性T淋巴细胞（CTL）裂解敏感的同时，它们对NK细胞和VV特异性CTL杀伤高度敏感时，其对裂解的敏感性丧失。这些结果表明，病毒感染的靶细胞在感染后的离散时间点可能对NK细胞的裂解作用天生更敏感，并且对裂解的敏感性与NK细胞的激活增强和H-2 I类抗原表达减少相关。
