Altered Expression of Natural Cytotoxicity Receptors and NKG2D on Peripheral Blood NK Cell Subsets in Breast Cancer Patients

Human natural killer (NK) cells are considered professional cytotoxic cells that are integrated into the effector branch of innate immunity during antiviral and antitumoral responses. The purpose of this study was to examine the peripheral distribution and expression of NK cell activation receptors from the fresh peripheral blood mononuclear cells of 30 breast cancer patients prior to any form of treatment (including surgery, chemotherapy, and radiotherapy), 10 benign breast pathology patients, and 24 control individuals. CD3(-)CD56(dim)CD16(bright) NK cells (CD56(dim) NK) and CD3(-)CD56(bright)CD16(dim/-) NK cells (CD56(bright) NK) were identified using flow cytometry. The circulating counts of CD56(dim) and CD56(bright) NK cells were not significantly different between the groups evaluated, nor were the counts of other leukocyte subsets between the breast cancer patients and benign breast pathology patients. However, in CD56(dim) NK cells, NKp44 expressionwas higher in breast cancer patients (P = .0302), whereas NKp30 (P = .0005), NKp46 (P = .0298), and NKG2D (P = .0005) expression was lower with respect to healthy donors. In CD56bright NK cells, NKp30 (P = .0007), NKp46 (P = .0012), and NKG2D (P = .0069) expressionwas lower in breast cancer patients compared with control group. Only NKG2D in CD56(bright) NK cells (P =.0208) and CD56(dim) NK cells (P = .0439) showed difference between benign breast pathology and breast cancer patients. Collectively, the current study showed phenotypic alterations in activation receptors on CD56(dim) and CD56(bright) NK cells, suggesting that breast cancer patients have decreased NK cell cytotoxicity.