en Radiation Biology Radiation Biology تحقيق بديع Original Research <div style="text-align: justify;">Background: The current study was designed to compare the genes expression levels of&nbsp;MHC-П,&nbsp;IL-8&nbsp;and&nbsp;IgM&nbsp;in the head kidney and liver (central organs), as well as gill tissue (mucosal surface) of juvenile rainbow trout.&nbsp;Materials and Methods:&nbsp;Juvenile rainbow trout were immunized with gamma-irradiated and formalin inactive trophonts with/without alginate nanoparticles against&nbsp;Ichthyophthirius multifiliis. On day 20 after bath-immunization, fish in all the treatments, except negative control, were exposed to live trophonts. On the 30^th&nbsp;day, fish tissues were analyzed by real-time PCR.&nbsp;Results:&nbsp;The&nbsp;IL-8&nbsp;expression up-regulated in the kidney, hepatic and gill of immunized fish with irradiated and formalin inactive trophonts plus alginate nanoparticles and non-immunized fish challenged with live trophonts (P<0.05). The&nbsp;MHC-II&nbsp;showed up-regulation in gill and kidney of immunized fish and non-immunized fish challenged with live trophonts while hepatic&nbsp;MHC-П&nbsp;was up-regulated in immunized fish with formalin inactive trophonts plus alginate nanoparticles (P<0.05). A significant increase in the&nbsp;IgM&nbsp;expression was detected in gills of immunized fish with irradiated trophonts with/without alginate nanoparticles and formalin inactive trophonts plus alginate nanoparticles (P<0.05). The renal&nbsp;IgM&nbsp;showed up-regulation in all of treatments (P<0.05). A significant increase in the hepatic&nbsp;IgM&nbsp;expression was in immunized fish via irradiated trophonts with/without alginate nanoparticles (P<0.05).&nbsp;Conclusion:&nbsp;These findings indicated that the higher expression of&nbsp;IgM, MHC-II and IL-8&nbsp;at the gill, kidney and liver could prove the potential of the entire treatments to enhance both mucosal and systemic immune responses in immunized fish with gamma irradiated trophonts against&nbsp;I. multifiliis.</div> <div style="text-align: justify;">&nbsp;</div> Rainbow trout, gamma- irradiated Ichthyophthirius multifiliis, alginate nanoparticles, systemic immune response. 955 962 http://ijrr.com/browse.php?a_code=A-10-1-887&slc_lang=en&sid=1 M. Heidarieh haidariehm81@gmail.com, 7900319475328460020393 7900319475328460020393 Yes Nuclear Science and Technology Research Institute, Karaj, Iran M. Akbari 7900319475328460020394 7900319475328460020394 No Department of Fisheries Science, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Iran H. Unger 7900319475328460020395 7900319475328460020395 No Animal Production and Health Laboratory, International Atomic Energy Agency (IAEA), Vienna, Austria