The cytotoxicity of select neutrophils in breast cancer patients and the role of chemokines in neutrophil cytotoxicity.

e22148 Background: Recent research in murine breast cancer models demonstrates that primary breast tumors can mobilize select neutrophils, which have the unique capacity to inhibit metastatic seeding in the lung through cell-kill mechanisms. (Granot Z et al. Cancer Cell. 2010). In both breast cancer patients and healthy women, we investigated whether neutrophils were cytotoxic to breast cancer cell lines. We also assessed whether serum chemokines were associated with neutrophil cytotoxicity. Methods: Neutrophils were purified from the blood of 59 randomly selected newly diagnosed pre-operative breast cancer patients without evidence of metastatic disease, 50 metastatic breast cancer patients, 15 DCIS patients, and 45 healthy female volunteers with no history of cancer. Cytotoxicity was evaluated by incubating neutrophils with luciferase labeled MDA-MB-231 cells. Luciferase activity was measured as a reflection of % cytotoxicity. Serum was also isolated from breast cancer patients and healthy volunteers. Millipore Milliplex Human Cytokine Plex Kit was used to assess the concentration of 42 different chemokines in each of the serum samples. Results: In comparison to healthy volunteers whose mean neutrophil cytotoxicity to MDA-MB-231 cells was 6.5%, pre-operative breast cancer patients demonstrated a mean neutrophil cytotoxicity of 13.4%, p<0.0001, metastatic patients mean neutrophil cytotoxicity was 19.4%, p <0.003 and DCIS patients had a mean neutrophil cytotoxicity of 11.7%. p <0.01. By Kruskal-Wallist test, the relative concentrations of three chemokines, Il.1a, MCP.1 and TNF-a, were found to have a statistically significant association with neutrophil cytotoxicity (p-value: 0.005, 0.002, 0.0005 respectively). Conclusions: Our work demonstrates the cytotoxic role of select neutrophils in the peripheral blood of breast cancer patients as contrasted with neutrophils from healthy women. We further demonstrate that select chemokines appear to be correlated with neutrophil cytotoxicity, in varying concentrations. Further studies are needed to evaluate the prognostic and therapeutic role of cytotoxic neutrophils as well as the role of chemokines in neutrophil cytotoxicity.