BACKGROUND Besides few data concerning the antiseptic properties against a range of microbial agents and the anti-inflammatory potential both in vitro and in vivo, little is known about the influence of Eucalyptus oil (EO) extract on the monocytic/macrophagic system, one of the primary cellular effectors of the immune response against pathogen attacks. The activities of this natural extract have mainly been recognized through clinical experience, but there have been relatively little scientific studies on its biological actions. Here we investigated whether EO extract is able to affect the phagocytic ability of human monocyte derived macrophages (MDMs) in vitro and of rat peripheral blood monocytes/granulocytes in vivo in absence or in presence of immuno-suppression induced by the chemotherapeutic agent 5-fluorouracil (5-FU). METHODS Morphological activation of human MDMs was analysed by scanning electron microscopy. Phagocytic activity was tested: i) in vitro in EO treated and untreated MDMs, by confocal microscopy after fluorescent beads administration; ii) in vivo in monocytes/granulocytes from peripheral blood of immuno-competent or 5-FU immuno-suppressed rats, after EO oral administration, by flow cytometry using fluorescein-labelled E. coli. Cytokine release by MDMs was determined using the BD Cytometric Bead Array human Th1/Th2 cytokine kit. RESULTS EO is able to induce activation of MDMs, dramatically stimulating their phagocytic response. EO-stimulated internalization is coupled to low release of pro-inflammatory cytokines and requires integrity of the microtubule network, suggesting that EO may act by means of complement receptor-mediated phagocytosis. Implementation of innate cell-mediated immune response was also observed in vivo after EO administration, mainly involving the peripheral blood monocytes/granulocytes. The 5-FU/EO combined treatment inhibited the 5-FU induced myelotoxicity and raised the phagocytic activity of the granulocytic/monocytic system, significantly decreased by the chemotherapic. CONCLUSION Our data, demonstrating that Eucalyptus oil extract is able to implement the innate cell-mediated immune response, provide scientific support for an additional use of this plant extract, besides those concerning its antiseptic and anti-inflammatory properties and stimulate further investigations also using single components of this essential oil. This might drive development of a possible new family of immuno-regulatory agents, useful as adjuvant in immuno-suppressive pathologies, in infectious disease and after tumour chemotherapy.

中文翻译：

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桉树精油对先天细胞介导的免疫反应的刺激作用。

背景除了关于对一系列微生物制剂的防腐性能和体外和体内抗炎潜力的数据很少外，人们对桉树油 (EO) 提取物对单核细胞/巨噬细胞系统的影响知之甚少，其中一种针对病原体攻击的免疫反应的主要细胞效应物。这种天然提取物的活性主要通过临床经验得到认可，但对其生物学作用的科学研究相对较少。在这里，我们研究了 EO 提取物是否能够影响体外人单核细胞衍生的巨噬细胞 (MDM) 和体内大鼠外周血单核细胞/粒细胞的吞噬能力，​​在存在或存在由化疗剂 5-氟尿嘧啶诱导的免疫抑制的情况下(5-FU)。方法通过扫描电子显微镜分析人类MDMs的形态学激活。吞噬活性的测试如下：ii) 口服 EO 后，通过使用荧光素标记的大肠杆菌的流式细胞术，在免疫活性或 5-FU 免疫抑制大鼠的外周血中的单核细胞/粒细胞中进行体内检测。使用 BD Cytometric Bead Array 人 Th1/Th2 细胞因子试剂盒测定 MDM 释放的细胞因子。结果 EO 能够诱导 MDM 的激活，显着刺激它们的吞噬反应。EO 刺激的内化与促炎细胞因子的低释放相结合，需要微管网络的完整性，这表明 EO 可能通过补体受体介导的吞噬作用起作用。EO给药后在体内也观察到先天细胞介导的免疫反应的实施，主要涉及外周血单核细胞/粒细胞。5-FU/EO联合治疗抑制了5-FU诱导的骨髓毒性并提高了粒细胞/单核细胞系统的吞噬活性，化疗显着降低。结论 我们的数据表明，桉树油提取物能够实施先天细胞介导的免疫反应，为这种植物提取物的额外用途提供科学支持，除了关于其防腐和抗炎特性的数据，并刺激进一步研究也使用单一这种精油的成分。这可能会推动开发一种可能的新免疫调节剂家族，可用作免疫抑制病理学的佐剂，