Stimulatory effect of <it>Eucalyptus </it>essential oil on innate cell-mediated immune response

• Main Authors: Rasi Guido, Federici Memmo, Mercuri Luana, Zonfrillo Manuela, Andreola Federica, Vallebona Paola, Serafino Annalucia, Garaci Enrico, Pierimarchi Pasquale
• Format: Article
• Language: English
• Published: BMC 2008-04-01
• Series: BMC Immunology
• Online Access: http://www.biomedcentral.com/1471-2172/9/17

<p>Abstract</p> <p>Background</p> <p>Besides few data concerning the antiseptic properties against a range of microbial agents and the anti-inflammatory potential both <it>in vitro </it>and <it>in vivo</it>, little is known about the influence of <it>Eucalyptus </it>oil (<it>E</it>O) 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 <it>E</it>O extract is able to affect the phagocytic ability of human monocyte derived macrophages (MDMs) <it>in vitro </it>and of rat peripheral blood monocytes/granulocytes <it>in vivo </it>in absence or in presence of immuno-suppression induced by the chemotherapeutic agent 5-fluorouracil (5-FU).</p> <p>Methods</p> <p>Morphological activation of human MDMs was analysed by scanning electron microscopy. Phagocytic activity was tested: i) <it>in vitro </it>in <it>EO </it>treated and untreated MDMs, by confocal microscopy after fluorescent beads administration; ii) <it>in vivo </it>in monocytes/granulocytes from peripheral blood of immuno-competent or 5-FU immuno-suppressed rats, after <it>EO </it>oral administration, by flow cytometry using fluorescein-labelled <it>E. coli</it>. Cytokine release by MDMs was determined using the BD Cytometric Bead Array human Th1/Th2 cytokine kit.</p> <p>Results</p> <p><it>E</it>O is able to induce activation of MDMs, dramatically stimulating their phagocytic response. <it>E</it>O-stimulated internalization is coupled to low release of pro-inflammatory cytokines and requires integrity of the microtubule network, suggesting that <it>E</it>O may act by means of complement receptor-mediated phagocytosis. Implementation of innate cell-mediated immune response was also observed <it>in vivo </it>after <it>E</it>O administration, mainly involving the peripheral blood monocytes/granulocytes. The 5-FU/<it>EO </it>combined treatment inhibited the 5-FU induced myelotoxicity and raised the phagocytic activity of the granulocytic/monocytic system, significantly decreased by the chemotherapic.</p> <p>Conclusion</p> <p>Our data, demonstrating that <it>Eucalyptus </it>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.</p>