Levels of circulating natural killer T and natural killer cells in breast cancer patients.

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e22034 Background: Invariant natural killer T (iNKT) cells are a unique subset of T lymphocytes that express markers characteristic of both T cells and natural killer (NK) cells. Following activation, iNKT cells rapidly produce a variety of cytokines and activate many other immune cells, thus iNKT cells are key mediators of innate immune responses (IIR) against tumors. The aim of this study was to assess the percentage (%) of iNKT, NKT-like, and NK cells in the peripheral blood of healthy volunteers (HV) and breast cancer (BC) patients. Methods: The % of circulating iNKT (Va24Ja18+CD3+), NKT-like (CD3+CD16CD56+), and NK (CD3-CD16CD56+) cells was analyzed by standardized flow cytometry in 22 newly diagnosed stage 0-3 BC patients and 27 HV. Luminal A BC was defined as ER/PR+≥1%, HER2- Ki67<20%. Differences between groups were assessed using the Mann-Whitney U test for nonparametric data and ANOVA for ≥ 3 groups. Results: iNKT cells % in BC patients (ages: 37-75) was significantly lower compared to HV (ages: 21-64) (Mean: 0.32 vs 0.12, p=0.0036). Among BC patients, NK cells were lower in patients aged ≥50 yrs (p=0.003) and with BMI ≥ 30 (p=0.0036). NK cell % was higher in Asians compared to other races. Patients with luminal A BC, which generally have the best prognosis, have a significantly higher % of NKT-like cells. Conclusions: Interestingly our data shows that older and obese BC patients have lower % of circulating NK cells, while patients with luminal A tumors have a higher % of NKT-like and a lower % of iNKT cells. Further studies on the effects of BMI and aging on IIR as well as functional studies are needed to better understand immunosenescence-related increasing incidence of cancers and IIR-mediated anti-tumor activity in BC patients. [caption]iNKT, NKT-like, and NK cells (% lymphocytes) by age, BMI, race, and pathology in BC patients.[/captions] [Table: see text]