S132 Abstracts / Toxicology Letters 211S (2012) S43–S216 P20-02 Effects of nanoparticles of titanium dioxide on the immune response to virus infection Wataru Watanabe 1 , Hiroki Yoshida 1 , Akihiko Hirose 2 , Katsuhiko Konno 1 , Masahiko Kurokawa 1 1 Kyushu University of Health and Welfare, Japan, 2 National Institute of Health Sciences, Japan Nanomaterials are ubiquitously used as industrial materials but their safety for human health is poorly known. To evaluate immunotoxicity of the nanoparticles of titanium dioxide, effects of the particles on the immune response to respiratory syncytial virus (RSV) infection in macrophages in vitro and mouse model in vivo were assessed. Titanium dioxide, MT-500B (rutile, 35 nm in diameter), was used in this study. RAW264.7 cells were treated with or without MT- 500B for 24 h. Subsequently, the cells were infected with the A2 strain of RSV and incubated for 72 h. After incubation, the amounts of TNF-alpha in the culture supernatants of the cells were measured by ELISA. Female (6 weeks old) BALB/c mice were exposed to MT- 500B intranasally at 0, 0.5 or 5 mg/kg under anesthesia. On day 5 after MT-500B exposure, the mice were infected with 1 × 10 6 PFU of RSV under anesthesia. MT-500B suppressed significantly (P < 0.05) the production of TNF-alpha in RSV-infected RAW264.7 cells. In a murine RSV infec- tion model, the levels of both TNF-alpha and IL-6 in bronchoalveolar lavage fluid of RSV-infected mice exposed to MT-500B decreased significantly (P < 0.05) compared with the control on day 1 post- infection. Although the pulmonary viral titers were not influenced due to MT-500B exposure, the gene expression of a chemokine RANTES in the lung tissues of RSV-infected mice were enhanced significantly (P < 0.05) compared with the control on day 5 post- infection. Thus, the nanoparticles of titanium dioxide might affect the immune cells and/or system responding to RSV infection. doi:10.1016/j.toxlet.2012.03.483 P20-03 Establishment of an in vitro photoallergen test using NCTC2544 cells and IL-18 Valentina Galbiati 1 , Sara Bianchi 1 , Veronica Martinez 2 , Montserrat Mitjans 2 , Emanuela Corsini 1 1 Università degli Studi di Milano, Italy, 2 Universitat de Barcelona, Spain Purpose: Differentiation between photoallergenic and photo- toxic reactions induced by low molecular weight compounds represents a current problem. The use of keratinocytes as a potential tool for the detection of photoallergens as opposed to photoirritants is considered an interesting strategy for developing in vitro methods. We have previously shown that IL-18 produc- tion in the human keratinocyte cell line NCTC2455 was a good model for screening sensitizers. The purpose of this work was to explore the NCTC2544 model as an in vitro model to identify photoallergenic and discriminate from phototoxic chemicals. Meth- ods: The effect of UVA radiation (3 J/cm 2 ) over NCTC2544 cells irradiated and non irradiated, and treated with increasing con- centrations of various compounds including negative compounds (irritants and allergens), ibuprofen and acridine (photoirritants); ketoprofen and chlorpromazine (photoirritant and photoaller- gen); benzophenone, 4-ter-butyl-4-methoxy-dibenzoylmethane, 2-ethylexyl-p-methoxycinnamate and 6-methylcumarin (photoal- lergens) was investigated. Twenty four hours after exposure, cytotoxicity was evaluated by the MTT assay, while the produc- tion of IL-18 was measured by a commercially available ELISA kit. Results: At the maximal concentration assayed with non cytotoxic effects, allergens and photoallergens induce the production of IL- 18, whereas irritants and photoirritants failed, indicating that the NCTC2544 assay can also be used to identify in vitro photoallergens. Acknowledgments: This project was funded by Ministero dell’Istruzione, dell’Università e della Ricerca (IT10B3A3AA) and by Ministerio de Ciencia e Innovación (IT2009-0014). doi:10.1016/j.toxlet.2012.03.484 P20-04 Investigation of sensitizing potency of some cosmetic mixtures Ozge Cemiloglu Ulker 1 , Ilker Ates 1 , Aysegul Atak 2 , Asuman Karakaya 1 1 Ankara University Faculty of Pharmacy, 2 Gazi University Faculty of Medicine, Turkey Balsam of Peru and Fragrans mix are commonly used in cosmetic products. In the present study, ex vivo Loval Lymph Node Assay- BrdU was used to evaluate the dermal sensitization potential of this cosmetic mixtures in order to improve animal welfare. The stimulation index values and estimated concentration (EC3) values were calculated and potency classification was found for each mixture. Ear thickness was also measured to determine the differentiation index (DI) which demonstrates the proportion of non-specific activation due to irritating properties of test com- pounds. Th1 cytokines (IL-2, IFN-) and Th2 cytokines (IL-4, IL-5) releases from lymph node cell culture as non-radioactive endpoints were investigated. According to the results of ex vivo LLNA-BrdU assays, EC3 val- ues were found to be 3.09% (moderate) for balsam of peru and 4.44% (moderate) for fragrance mix. As the differentiation index was found bigger than one for each test compounds, irritant effect was not detected for all applied concentrations. Cytokine analyses results indicate that both Th1 and Th2 cytokines are involved in the regulation of murine contact allergy and can be considered as useful endpoints. doi:10.1016/j.toxlet.2012.03.485 P20-05 Effect of administration of safranal on prevention of experimental autoimmune encephalomyelitis (EAE) Azam Bakhtiarian 1 , Fatemeh Ghasemi-Sakha 2 , Keyvan Keramati 3 , Seyyed-Mohammad Moazzeni 4 , Mohammad-Mehdi Eftekharian 5 , Vahid Nikoui 6 1 Tehran Univ. of Medical Sciences, Iran, 2 Islamic Azad University of Damghan, Iran, 3 Semnan University, Semnan, Iran, 4 Tarbiat Modarres University, Tehran, Iran, 5 Hamedan University of Medical Sciences, Iran, 6 Tehran University of Medical Sciences, Iran Purpose: Saffron as a herbal drug, considered because of a vari- ety of aspects such as anti-tumor, anti-inflammatory, antioxidant and anti-convulsant effects. In this study the anti-oxidant effects of safranal in EAE disease (the animal model of MS disease) is inves- tigated. Methods: In this experimental study, male mice C57BL/6