• Tomislav Jukić, Ana Jurin Martić, Siniša Ivanković, Mariastefania Antica, Doroteja Pavan Jukić, Cecilija Rotim, and Mislav Jurin.
• 1Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, Department of Internal Medicine, Family Medicine and History of Medicine, Osijek, Croatia; 2Čakovec County Hospital, Čakovec, Croatia; 3Faculty of Dental Medicine and Health, Josip Juraj Strossmayer University of Osijek, Osijek, Croatia; 4Rudjer Bošković Institute, Division of Molecular Medicine, Zagreb, Croatia; 5Rudjer Bošković Institute, Division of Molecular Biology, Zagreb, Croatia; 6Faculty of Medicine, Josip Juraj Strossmayer University of Osijek, Department of Department of Gynecology and Obstetrics, Osijek, Croatia; 7Dr Andrija Štampar Teaching Institute of Public Health, Zagreb, Croatia.
• Acta Clin Croat. 2020 Jun 1; 59 (2): 351-358.

AbstractThe role of T regulatory lymphocytes (Treg) particularly in cancer is well known. The goal of the present study was to determine the contribution of these lymphocytes in the regulation of anti-tumor immunity of CBA/HZgr mice against MC-2 fibrosarcoma (4th generation of methylcholanthrene induced tumor). The levels of T lymphocytes (CD4+, CD8+ and CD4+CD25+) were determined 8 and 20 days after tumor transplantation. Further, the role of CD4+CD25+ (Tregs) in tumor-host interaction was evaluated in vitro and in vivo by using specific monoclonal antibodies. We found that splenocytes of both control and Treg depleted tumor bearing mice strongly but differently inhibited growth of tumor cells in vitro. While splenocytes of untreated mice exhibited significant decrease of this activity (from 74.4% to 62.6% and 32.95%), the splenocytes of Treg depleted mice showed increase of this activity (from 79.5% to 84.3% and 86.2%) from day 6 to day 13 and day 21 after tumor grafting, respectively. Further, upon i.v. injecting specific monoclonal anti-Treg antibody tumor immediately prior to tumor cell intracutaneous transplantation, the tumor was rejected after initial growth. In treated mice, the incidence of Treg cells was very low initially, reaching normal values two weeks later. These animals were shown to be resistant to tumor transplantation four months later.

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