1Cancer Immunology Group, Shiraz Institute for Cancer Research, School of Medicine
2Department of Obstetrics and Gynecology, School of Medicine
3Professor Alborzi Clinical Microbiology Research Center, Nemazee Hospital, Shiraz University of Medical Sciences, Shiraz, Iran
Background: Ovarian cancer is the fifth leading cause of death from malignancy in women. CD4 +CD25+FoxP3+ regulatory T (Treg) cells are a subset of T lymphocytes with great inhibitory impact on immune response. Objectives: To investigate the percentage of CD4 +CD25+FoxP3+ regulatory T cells in the peripheral blood of the Iranian patients with epithelial ovarian cancer compared to healthy women and to evaluate the correlation of the Treg cell percentage with clinicopathological characteristics including cancer stage and CA-125 serum level. Methods: Seventeen women with epithelial ovarian cancer and 20 healthy subjects were enrolled in the study. Peripheral blood mononuclear cells were stained at the surface, for CD4 and CD25 molecules, followed by fixation, permeabilization and intracellular staining for FoxP3 molecule. After processing and flowcytometry analysis, prevalence of Treg cells was determined as the percentages of CD25 +FoxP3+ cells among CD4+ lymphocytes. Results: Despite no difference in the percentage of total CD4+ lymphocytes, analysis indicated that Treg cell percentage was significantly higher in ovarian cancer patients than controls (5.7 ± 3.1% versus 2.8 ± 1.4%, p=0.002). A trend toward higher Treg cells was observed in higher stages of ovarian cancer (III+IV) in comparison to lower stages (I+II) (6.5 ± 3.2% vs. 4.44 ± 2.7%, p=0.2). Higher percentage of Treg cells was also observed in the patients with high CA125 (CA-125 >100 U/mL) in comparison to those with low CA-125 serum level (CA-125 ≤100 U/mL) although the difference was not significant (6.44 versus 4.18%, p=0.19). Conclusion: Increased frequency of Tregs in ovarian cancer might participate in immune suppression in these patients. The findings collectively suggest the likely impact of Treg cell–targeted immunotherapy in ovarian cancer.