Objectives: To determine peripheral frequencies of CD4(+)CD25(high)Foxp3(+) regulatory T cells (Treg) in prostate cancer (PCa) patients, and to investigate if there is a correlation between peripheral Treg and total serum prostate specific antigen (PSA) levels in PCa patients.

Methods: Peripheral blood mononuclear cells from 56 subjects undergoing diagnostic prostate biopsies (PSA >= 2.5ng/ml) were analyzed for Treg numbers. Association between the peripheral Treg and serum PSA values was first determined in the entire population, including people with no prostate pathology, PCa, and benign prostate hyperplasia (BPH) patients, and second, in 9 PCa patients before and after curative prostatectomy. In this study, the 3 groups were compared. This project was performed in the Akdeniz University Immunology laboratory, and the Urology outpatient clinic, Antalya, Turkey from December 2008 to January 2010.

Results: Peripheral Treg frequencies were significantly increased in the PCa patients (n=19, 3.23 +/- 1.59) compared with BPH patients (n=27, 1.66 +/- 0.80), and healthy subjects (n=10, 1.08 +/- 0.43) (p=0.007). The percentage of Treg in BPH patients was also significantly higher than healthy subjects (p=0.007). The increase of Treg in BPH and PCa patients was positively correlated with total serum PSA levels (r=0.75; p=0.007).

Conclusion: Peripheral Treg densities are correlated with PSA in BPH and PCa patients, suggesting that PSA may have a role in Treg induction and/or maintenance