Enumeration of CD3ˉCD56⁺CD16⁺ and NKG2D⁺ Natural Killer Cells in Breast Cancer Patients

Introduction: Breast cancer is a malignant disease of breast tissue. The immune system consists of cells, molecules, and organs that play a vital role in eliminating pathogens, toxins, allergens, and tumor cells. Cytotoxic T cells (CD8+) and natural killer (NK) cells are the major effector cells responsible for killing tumor cells. Objective: This study was designed to determine the percentage of NK cells, NK cell subsets (CD56brightCD16- and CD56dimCD16+), and the activating receptor NKG2D in the peripheral blood of breast cancer patients. Study Design: Prospective case control Place and duration: This study was conducted between August 2017 and March 2018 at INMOL Hospital, Lahore, Pakistan. Methodology: This was a comparative study that included 80 subjects (40 healthy controls and 40 breast cancer patients). The study included patients diagnosed with ductal carcinoma in situ (DCIS, n=6), invasive ductal carcinoma (IDC, n=33), and invasive lobular carcinoma (ILC, n=1). According to the American Cancer Society criteria (2017), the majority of patients were classified as grade 2 (n=25), followed by grade 3 (n=12) and grade 1 (n=3). Additionally, forty healthy controls, aged 26 to 60 years, with no history of malignancy or chronic disorders, were included. Results: The mean ± SD of NK cells were higher in breast cancer patients (9.5 ± 5.2) compared to healthy controls (8.5 ± 5.3); however, the difference was not statistically significant (p = 0.39). The expression of NKG2D was higher in the control group (67 ± 16.3) compared to patients (52 ± 28.1), and this difference was statistically significant (p = 0.005). Breast cancer patients had a higher mean ± SD for the CD56bright subset (1.8 ± 1.1) compared to healthy controls (1.1 ± 0.5), and this difference was statistically significant (p = 0.001). Similarly, breast cancer patients had a higher mean ± SD for the CD56dim subset (12.4 ± 8.2) compared to healthy controls (11.2 ± 5.7); however, this difference was not statistically significant (p = 0.445). Conclusion: The current study suggested that breast cancer patients modulate the abundance of NK cell subsets and alter the expression of NKG2D on the surface of peripheral blood NK cells which may decrease NK cell cytotoxicity.