IL-17 Expression by macrophages is associated with proliferative inflammatory atrophy lesions in prostate cancer patients.

Intraprostatic leukocyte function may vary depending on local inflammatory or malignant cell microenvironment. Interleukin (IL)-17 producing cells play key roles in chronic inflammation and autoimmunity. Little is known about the relevance of IL-17 producing cells at sites of prostate tissue inflammation and/or prostate adenocarcinoma. In this study, we analyzed thirty formalin-fixed paraffin-embedded whole-mount radical prostatectomy specimens of prostate cancer patients. Immunohistochemistry was employed to identify IL-17 producing cells in all sites of mononuclear cell accumulation, noting their relationships to areas of prostate cancer, proliferative inflammatory atrophy (PIA), or hyperplastic benign tissue. Levels of IL-17 producing cells were similar in zones of benign prostate tissue and areas of prostate cancer. Pronounced intraluminal and peri-glandular IL-17 producing cell accumulations were identified in the mononuclear cell infiltrates associated with PIA lesions. Glandular and peri-glandular CD68+ macrophages and neutrophils were the predominant IL-17 producing cells in PIA lesions. The accumulation of IL-17 expressing cells in PIA lesions presents direct evidence of an inflammatory microenvironment that may support the development of prostate cancer.