Radiotherapy-induced changes of peripheral blood lymphocyte subpopulations in cervical cancer patients: relationship to clinical response A. Eric 1a , Z. Juranic 1a , N. Tisma 1a , V. Plesinac 1b,2 , N. Borojevic 1b,2 , D. Jovanovic 1c , Z. Milovanovic 1c , D. Gavrilovic 1d , B. Ilic 1a 1 Institute of Oncology and Radiology of Serbia, Belgrade, 2 University of Belgrade Medical School, Belgrade, Serbia, a Department of a Experimental Oncology, b Department of Radiology, b c Department of Pathology, c d Data Center d Summary Purpose: To determine the absolute number and percent - age of peripheral blood lymphocyte subpopulations positive (+) cells CD8 + , CD8 + NKG2D + , CD8 + , Granzyme B + (GrB), CD16 + , CD16 + NKG2D + , CD56 + and CD56 + NKG2D + in cervical cancer patients before and after radiotherapy (RT), and to analyze whether their changes are related to the clini- cal response. Materials and methods: Stage IIB - IVA cervical cancer patients received external irradiation and concomitant intra- cavitary brachytherapy. Blood samples for immunophenotypic analysis by flow cytometry were collected from each patient one day before starting RT and one day after completing RT. Fifteen healthy volunteers served as controls. Surface marker expression and granzyme B positivity were quantified on FAC- SCalibur flow cytometer. Results: Unlike their absolute numbers, the percent- ages of all analyzed lymphocyte subsets of all patients, including those with complete response (CR), were sig- nificantly increased (p <0.05) after RT. Only in patients with progressive disease (PD), CD8 + , CD8 + NKG2D + , CD16 + and CD56 + NKG2D + lymphocytes were not significantly in- creased. In healthy volunteers, the percentage of CD8 + GrB + lymphocytes was lower than in patients after RT, while the percentages of CD56 + and CD56 + NKG2D + cells were higher than in patients before RT (p <0.05). Conclusion: Our data indicate that RT , besides its direct cytoreductive effect on tumor cells, may contribute to better immunological control of cervical cancer. Key words: lymphocyte subsets, radiotherapy, treatment outcome, uterine cervical neoplasms Introduction After postulating human papillomavirus (HPV) as the cause of cervical cancer [1,2], many studies in the field of tumor immunology were carried out, in order to recognize the nature and role of cellular and humoral immune response to this tumor’s antigens [3-5]. These attempts resulted in developing prophylactic and thera- peutic cervical cancer vaccines [6-8]. Nevertheless, this cancer still has a high rate of incidence and mortality , especially in developing countries [9]. Although there are many publications dealing with RT-induced im- munosuppression [10-12], recent studies showed that R T may initiate and enhance antigen-specific immune response [13,14]. Besides, the natural killer (NK) cells also play an important role in host anti-cancer defense mechanisms [15]. They are capable of dual cytolytic activity: non-MHC-restricted cytotoxicity and anti- body-dependent cellular cytotoxicity (ADCC) [16]. The majority of NK cells express CD16 + (Fcγ R III) and CD56 surface antigens [15]. CD16 + binds the Fc region, mainly of human IgG1 and IgG3 [16]. NK cells and CD8 + cytotoxic lymphocytes may express NKG2D transmembrane stimulatory immunoreceptor, the acti- vation of which stimulates cytolysis and cytokine pro- duction by NK cells and provides costimulatory signal Correspondence to: Zorica Juranic, PhD. Institute of Oncology and Radiology of Serbia, Pasterova 14, 11000 Belgrade, Serbia. Tel: +381 11 2067210, Fax: +381 11 2685300, E-mail: juranicz@ncrc.ac.yu Received 13-05-2008; Accepted 10-07-2008 Journal of BUON 14: 79-83, 2009 © 2009 Zerbinis Medical Publications. Printed in Greece ORIGINAL ARTICLE