Department of Anesthesiology, Pain and Perioperative Medicine, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115, USA.
Anesth Analg. 2011 Apr;112(4):830-8. doi: 10.1213/ANE.0b013e31820dcabb. Epub 2011 Mar 8.
Sedative drugs modify immune cell functions via several mechanisms. However, the effects of sedatives on immune function have been primarily investigated in neutrophils and macrophages, and to the lesser extent lymphocytes. Lymphocyte function-associated antigen-1 (LFA-1) is an adhesion molecule that has a central role in regulating immune function of lymphocytes including interleukin-2 (IL-2) production and lymphocyte proliferation. Previous clinical studies reported that propofol and isoflurane reduced IL-2 level in patients, but midazolam did not. We previously demonstrated that isoflurane inhibited LFA-1 binding to its counter ligand, intercellular adhesion molecule-1 (ICAM-1), which might contribute to the reduction of IL-2 levels. In the current study, we examined the effect of propofol, midazolam, and dexmedetomidine on LFA-1/ICAM-1 binding, and the subsequent biological effects.
The effect of sedative drugs on T-cell proliferation and IL-2 production was measured by calorimetric assays on human peripheral blood mononuclear cells. Because LFA-1/ICAM-1 binding has an important role in T-cell proliferation and IL-2 production, we measured the effect of sedative drugs on ICAM-1 binding to LFA-1 protein (cell-free assay). This analysis was followed by flow cytometric analysis of LFA-1 expressing T-cell binding to ICAM-1 (cell-based assay). To determine whether the drug/LFA-1 interaction is caused by competitive or allosteric inhibition, we analyzed the sedative drug effect on wild-type and high-affinity LFA-1 and a panel of monoclonal antibodies that bind to different regions of LFA-1.
Propofol at 10 to 100 μM inhibited ICAM-1 binding to LFA-1 in cell-free assays and cell-based assays (P < 0.05). However, dexmedetomidine and midazolam did not affect LFA-1/ICAM-1 binding. Propofol directly inhibits LFA-1 binding to ICAM-1 by binding near the ICAM-1 contact area in a competitive manner. At clinically relevant concentrations, propofol, but not dexmedetomidine or midazolam, inhibited IL-2 production (P < 0.05). Additionally, propofol inhibited lymphocyte proliferation (P < 0.05).
Our study suggests that propofol competitively inhibits LFA-1 binding to ICAM-1 on T-cells and suppresses T-cell proliferation and IL-2 production, whereas dexmedetomidine and midazolam do not significantly influence these immunological assays.
镇静药物通过多种机制改变免疫细胞功能。然而，镇静剂对免疫功能的影响主要在中性粒细胞和巨噬细胞中进行了研究，而在淋巴细胞中则研究较少。淋巴细胞功能相关抗原-1（LFA-1）是一种黏附分子，在调节包括白细胞介素-2（IL-2）产生和淋巴细胞增殖在内的淋巴细胞免疫功能方面发挥着核心作用。先前的临床研究报告称，异丙酚和异氟烷降低了患者的 IL-2 水平，但咪达唑仑没有。我们之前的研究表明，异氟烷抑制 LFA-1 与其配体细胞间黏附分子-1（ICAM-1）的结合，这可能导致 IL-2 水平降低。在本研究中，我们研究了异丙酚、咪达唑仑和右美托咪定对 LFA-1/ICAM-1 结合的影响，以及随后的生物学效应。
通过人外周血单核细胞的比色测定法测量镇静药物对 T 细胞增殖和 IL-2 产生的影响。由于 LFA-1/ICAM-1 结合在 T 细胞增殖和 IL-2 产生中具有重要作用，我们测量了镇静药物对 LFA-1 蛋白与 ICAM-1 结合的影响（无细胞测定法）。然后通过流式细胞术分析 LFA-1 表达的 T 细胞与 ICAM-1 的结合（基于细胞的测定法）。为了确定药物/LFA-1 相互作用是竞争性还是变构抑制引起的，我们分析了镇静药物对野生型和高亲和力 LFA-1 以及一组结合 LFA-1 不同区域的单克隆抗体的影响。
10 至 100μM 的异丙酚在无细胞测定法和基于细胞的测定法中均抑制 ICAM-1 与 LFA-1 的结合（P<0.05）。然而，右美托咪定和咪达唑仑不影响 LFA-1/ICAM-1 结合。异丙酚通过竞争性结合与 ICAM-1 接触区域附近的 LFA-1 直接抑制 LFA-1 与 ICAM-1 的结合。在临床相关浓度下，异丙酚而非右美托咪定或咪达唑仑抑制 IL-2 的产生（P<0.05）。此外，异丙酚抑制淋巴细胞增殖（P<0.05）。
我们的研究表明，异丙酚竞争性抑制 T 细胞上 LFA-1 与 ICAM-1 的结合，并抑制 T 细胞增殖和 IL-2 的产生，而右美托咪定和咪达唑仑则不会显著影响这些免疫学测定。
