Gan Xiaohu, Zhang Ling, Solomon George F, Bonavida Benjamin
Department of Microbiology and Immunology, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
Brain Behav Immun. 2002 Jun;16(3):227-46. doi: 10.1006/brbi.2000.0615.
Norepinephrine (NE) has been shown to inhibit human peripheral blood-derived natural-killer (NK) cell cytotoxicity (NKCC) in vitro. We demonstrate in this study that NE not only inhibits IL-2-activated NKCC but antibody-dependent cellular cytotoxicity (ADCC) as well. NK cytotoxicity by purified NK cells against K562 (NKCC) and against Raji cells (ADCC) were inhibited by NE (1-100 microM) by more than 50% in a 4-h (51)Cr release assay. The mechanism underlying the inhibition has been examined. NK cytotoxicity is dependent on target recognition and formation of NK-target conjugates, and activation by IL-2 is dependent on the secretion of cytokines (such as TNF-alpha) by NK cells. We hypothesized that the inhibition of NK functions by NE may be due to disruption of NK-target conjugation, blocking programming for lysis, and/or inhibition of cytokine secretion. Pretreatment of human peripheral blood mononuclear cells (PBMC) with NE for 15 min significantly reduced the binding to K562 cells by CD16(+) NK lymphocytes. In the presence of K562 cells, NE down-regulated the expression of CD16 (FcgammaRIII) by human PBMC, an NK cell receptor responsible and necessary for ADCC and cytokine secretion. We also demonstrate that NE inhibited the IL-2-mediated up-regulation of the activation marker CD69. At concentrations of 10(-6) to 10(-5) M, NE inhibited TNF-alpha, IFN-gamma, and GM-CSF secretion by NK cells, which are essential for IL-2-driven NK maturation and functions. In addition, using single-cell analysis, NE pretreatment of lymphocytes reduced the frequency of killer cells in the NK-K562 conjugate population in a concentration-dependent manner, indicating an inhibition of the programming for lysis by NK cells. In summary, these data demonstrate that NE-induced inhibition of NK cytotoxicity is manifested at multiple levels, including a modification of NK cell receptor ligation to target cells, blockade of NK cytokine secretion necessary for NK maturation and differentiation, and inhibition of the target-induced activation of the cytotoxic mechanism(s) in NK cells. Thus, sympathetic activation, as often induced experimentally, may profoundly impair natural cellular immunity through varied measurable pathways.
去甲肾上腺素（NE）已被证明在体外可抑制人外周血来源的自然杀伤（NK）细胞的细胞毒性（NKCC）。我们在本研究中证明，NE不仅抑制IL-2激活的NKCC，还抑制抗体依赖性细胞毒性（ADCC）。在4小时的（51）铬释放试验中，NE（1-100微摩尔）可使纯化的NK细胞对K562细胞的细胞毒性（NKCC）和对Raji细胞的细胞毒性（ADCC）抑制超过50%。我们对抑制作用的潜在机制进行了研究。NK细胞毒性依赖于靶细胞识别和NK-靶细胞共轭物的形成，而IL-2的激活则依赖于NK细胞分泌细胞因子（如TNF-α）。我们推测，NE对NK功能的抑制可能是由于破坏了NK-靶细胞共轭、阻断裂解编程和/或抑制细胞因子分泌。用NE预处理人外周血单个核细胞（PBMC）15分钟，可显著降低CD16（+）NK淋巴细胞与K562细胞的结合。在有K562细胞存在的情况下，NE可下调人PBMC中CD16（FcγRIII）的表达，CD16是一种对ADCC和细胞因子分泌起作用且必需的NK细胞受体。我们还证明，NE可抑制IL-2介导的激活标志物CD69的上调。在10^-6至10^-5 M的浓度下，NE可抑制NK细胞分泌TNF-α、IFN-γ和GM-CSF，这些细胞因子对IL-2驱动的NK细胞成熟和功能至关重要。此外，通过单细胞分析，用NE预处理淋巴细胞可使NK-K562共轭群体中的杀伤细胞频率以浓度依赖的方式降低，这表明NE抑制了NK细胞的裂解编程。总之，这些数据表明，NE诱导的NK细胞毒性抑制在多个层面上表现出来，包括改变NK细胞受体与靶细胞的连接、阻断NK细胞成熟和分化所需的NK细胞因子分泌，以及抑制靶细胞诱导的NK细胞细胞毒性机制的激活。因此，如实验中经常诱导的交感神经激活，可能通过多种可测量的途径严重损害天然细胞免疫。
