Circulating Plasmacytoid and Myeloid Dendritic Cells in Breast Cancer Patients: A Pilot Study

Dendritic cells (DC) are a class of bone marrow-derived cells found in the blood, epithelia, and lymphoid tissues, and are the most efficient antigen presenting cells. The number and function of DC can change dramatically in cancer patients. The aim of this study is to correlate the levels of circulating DC subsets with clinical characteristics in breast cancer patients.

Peripheral blood samples were collected from 53 untreated breast cancer patients before surgery between January 2013 and November 2013. Forty-one healthy, age-matched volunteers served as the control group. The phenotypes of circulating plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) were determined using fluorescence activated cell sorting assays. Correlations between DCs immunophenotypes and clinicopathologic characteristics of these breast cancer patients were then determined.

Patients with breast cancer had higher levels of pDCs (p = 0.046). No relationships were observed with tumor stage and intrinsic subtype. Estrogen receptor (ER) positive patients had higher levels of mDCs than ER negative patients (p = 0.025) and human epidermal growth factor receptor 2 (HER-2) positive patients had higher levels of pDCs than HER-2 (p = 0.040). No relationships were observed with T stage, N stage, Ki67 index, histologic grade, nuclear grade, and lymphovascular invasion. In multiple regression analysis, patients with HER-2 positive breast cancer had higher levels of pDCs than HER-2 negative patients (p = 0.026).

An increase of pDCs in the peripheral blood of breast cancer patients was observed and patients with HER-2 positive breast cancer had higher levels of circulating pDCs than did HER-2 negative patients. Our results suggest that expression of DCs can differ according to breast cancer subtype and indicate that, with further investigation, DC expression has the possibility of being presented as a prognostic factor.