Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 9 3 2014 09 15 311 318 EN Habib Mohammadzadeh Hajipirloo Dept. of Medical Parasitology and Mycology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran. Arezoo Bozorgomd Dept. of Medical Parasitology and Mycology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran. Shahram Shahabi Dept. of Microbiology, Immunology and Genetics, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran. Khosrow Hazrati Tappeh Dept. of Medical Parasitology and Mycology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran. Seyed Ahmad Karamati Dept. of Medical Parasitology and Mycology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2015 10 14 Background: Naltrexone, an opioid receptor antagonist shifts the immune response toward a Th1 profile. In the current study, we evaluated the efficacy of the mixture of NTX and alum, as a new adjuvant, to enhance immune response and induce protection against Leishmania major in a mouse model. Methods: BALB/c mice were immunized three times either autoclaved L.major promastigotes’ antigens alone or in combination with the adjuvant alum, naltrexone or the alum–naltrexone mixture. Both humoral and cellular immune responses were assessed two weeks after the last immunization and compared with control mice. Results: The administration of alum- NTX in combination with the parasite antigen, significantly increased production of IFN-γ, IFN-γ /IL-5 ratio,lymphocyte proliferation and improved DTH response against L. major.There was no significant difference in survival following challenge among groups. Conclusion: Immunization with the alum– naltrexone mixture as an adjuvant,in combination with the autoclaved L. major promastigotes antigens,can enhance cellular immunity and shift the immune responses to a Th1 pattern. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/397 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/397/347