Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 7 4 2008 12 15 203 208 Nikoo Shohreh Department of Immunology, School of Medicine, Tarbiat Modarres University of Medical Sciences, Tehra Bozorgmehr Mahmood Department of Immunology, School of Medicine, Tarbiat Modarres University of Medical Sciences, Tehra Namdar Ahmadabad Hasan Department of Immunology, School of Medicine, Tarbiat Modarres University of Medical Sciences, Tehra Mohammad Hassan Zuhair Department of Immunology, School of Medicine, Tarbiat Modarres University of Medical Sciences, Tehra Moazzeni Seyed Mohammad Department of Immunology, School of Medicine, Tarbiat Modarres University of Medical Sciences, Tehra Pourpak Zahra Immunology, Asthma and Allergy Research Institute, Tehran University of Medical Sciences, Tehran, Ir Ghazanfari Tooba Department of Immunology, School of Medicine, Shahed University of Medical Sciences, Tehran, Iran 2015 10 01 A wide range of biological activities of garlic in vitro and in vivo have been verified including its antioxidant, antitumor and anti-inflammatory effects. Indoleamine 2,3-dioxygenase (IDO) is an enzyme widely distributed in mammals and is inducible preferentially by IFN-γ. IDO degrades the essential amino acid tryptophan to form N-formyl kynurenine. In the present in vitro study, the modulatory effect of 14kDa molecule isolated from garlic on IDO induction was tested. Cultures of mononuclear cells were exposed to 14kDa garlic fraction. Then, their proliferation responses and IDO metabolites were measured. A significant down-regulatory effect of garlic on IDO activity was found and also the proliferation responses of mononuclear cells increased. If these results are verified in vivo, an explanation will be provided on how garlic may interfere in IDO induction, which paves the way for elucidating its specific therapeutic effect in preventing tumor progress. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/220 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/220/220