Increased interleukin-35 expression in tumor-infiltrating lymphocytes correlates with poor prognosis in patients with breast cancer

Abstract Interleukin-35 (IL-35) is a recently discovered inhibitory cytokine, which is firstly discovered to be produced by regulatory T cells (Tregs) and proposed as a key effector molecule of Treg function. This study aims to analyze the correlation between IL-35 expression in tumor-infiltrating lymphocytes (TILs) of breast cancer tissue and patients’ clinical characteristics. Plasma IL-35 was also determined in 60 patients with breast invasive ductal carcinoma (IDC) and 30 healthy women by enzyme-linked immunosorbent assay. IL-35 expression in the tissue specimens was analyzed by immunohistochemistry. It was shown that 39.1%, 43.6% and 17.3% of the 110 patients were absent, weak, and strong IL-35 expression in the TILs, respectively. Strong IL-35 expression in TILs was significantly associated with age >50 years, tumor size >2 cm, TNM stage III, and negative ER (All P  P P