Table 1 Summary of key immune cells and cytokines found in the tumor microenvironment of prostate cancer

Treg

Definition is constantly refined; however, FoxP3 is consistently expressed. Highly prevalent in prostate cancer tissues. Potential roles include immunosuppression, allowing tumors to escape from immunosurveillance

[9, 11, 13, 84]

Th17 cells

CD4⁺ T cells that express high levels of IL-17. The number of Th17 cells in tumors inversely associates with tumor grade, and the number of Th17 cells in peripheral blood inversely correlates with time to progression in patients with prostate cancer

[10, 17, 18]

Macrophages

Recruited to tumors by chemotactic factors such as CCL2. Produce a variety of pro-inflammatory factors that promote angiogenesis and tumor growth. The increased amount of tumor-infiltrating macrophages directly associates with an unfavorable prognosis

[85–88]

IL-6

A pro-inflammatory cytokine. Elevated levels of IL-6 are associated with prostate cancer biochemical recurrence. Promote prostate cancer cell growth in vitro and in vivo

[40, 42, 54]

RANKL

Produced by activated T cells and osteocytes. Target dendritic cells to promote antigen presentation. Tumors can directly produce RANKL or induce RANKL expression from the TME, resulting in osteoclastogenesis and tumor-induced bone resorption

[58, 60, 72, 83]