Analysis of circulating regulatory T cells (CD4+CD25+CD127-) after cryosurgery in prostate cancer

This study was performed to assess the response of regulatory T cells (Tregs) following cryosurgery in prostate cancer (PCa) patients by measuring their frequency and immune function. Blood was collected prior to and at 4 and 8 weeks after treatment in 30 patients with high-risk PCa who underwent cryosurgery and from 15 healthy volunteers. Circulating CD4(+)CD25(+)CD127(-) Tregs were isolated. Their frequency was detected by flow cytometry, and immune suppressive function was evaluated by measuring the proliferation of CD4(+)CD25(-) T cells cocultured with Tregs. The results showed that the percentage of circulating CD4(+)CD25(+)CD127(-) Tregs was increased in PCa patients compared to healthy volunteers (7.6%+/- 0.73% vs. 5.8%+/- 0.54%, P<0.001). The frequency of circulating CD4(+)CD25(+)CD127(-) Tregs was reduced 4 weeks after cryosurgery compared to before surgery (6.3%+/- 0.58% vs. 7.6%+/- 0.73%, P<0.001), and the decrease persisted for 8 weeks. However, the suppressive function of Tregs was increased in eight of 12 patients, which might contribute to cancer recurrence. Then the response of circulating Tregs is complicated after cryosurgery for PCa, and further studies are warranted.