Myeloid suppressor cells are commonly found in tumors and contribute to the immunosuppressive microenvironment. In Science Immunology, Condamine et al. identify a population of suppressive polymorphonuclear cells present in the circulation and within tumors obtained from patients with cancer. These human suppressor cells express the lectin-type oxidized low-density lipoprotein receptor LOX-1 and exhibit differences in gene expression that distinguish them from normal neutrophils obtained from the same patients and healthy donors. This distinct gene profile is associated with the induction of endoplasmic reticulum stress and expression of the transcription factor sXBP-1. Treatment of normal neutrophils with thapsigargin leads to their acquisition of immunosuppressive activity, whereas inhibitors of XBP-1 prevent such activity. These findings provide a new tumor biomarker, LOX-1, and suggest a means by which such cells might be targeted for therapeutic benefit.

Sci. Immunol. 1, aaf8943 (2016)