CD16 + monocytes in breast cancer patients: expanded by monocyte chemoattractant protein‐1 and may be useful for early diagnosis

Summary Human peripheral blood monocytes are a heterogeneous population, including CD14 + CD16 ‐ ‘classical’ monocytes and CD14 + CD16 + ‘proinflammatory’ monocytes. CD16 + monocytes are expanded in various inflammatory conditions. However, little is known about the CD14 + CD16 + monocytes in patients with breast cancer. We detected CD14 + CD16 + monocytes in 96 patients with breast cancer and 54 control subjects using flow cytometry. Receiver‐operating characteristic (ROC) curve analysis was used to determine the feasibility of CD14 + CD16 + monocytes as an indicator for diagnosis of breast cancer. We found that the frequency of CD14 + CD16 + monocytes showed a significantly greater increase in breast cancer patients than in controls (16·96% versus 10·84%, P  < 0·0001). The area under the ROC curve for CD14 + CD16 + monocytes was 0·805 [95% confidence interval (95% CI): 0·714–0·877, P  = 0·0001]. Furthermore, the levels of CD16 + monocytes were significantly negatively associated with the tumour size and pathological staging. In vitro , we showed that CD14 + CD16 + monocytes were expanded significantly when the purified CD14 + monocytes were exposed to Michigan Cancer Foundation (MCF)‐7 cells‐conditioned medium (MCF‐CM) or, separately, to monocyte chemotactic protein 1 (MCP‐1). Neutralizing antibodies against MCP‐1 inhibited the expansion of CD14 + CD16 + monocytes by MCF‐CM. Collectively, our findings indicated that MCP‐1 can expand CD14 + CD16 + monocytes in patients with breast cancer. Furthermore, the CD14 + CD16 + monocyte may be a useful indicator in early diagnosis of breast cancer.