Neutrophils from patients with HNC do not show spontaneous suppression of T-cell activation. (A-B) Purified T cells from control donors were cultured with anti-CD3 and anti-CD28 antibodies (red bars) and in the presence of neutrophils from control donors (blue bars) or patients with HNC (A: green bars, 8 donors tested in duplicate) or patients with MC (B: green bars, 3 donors tested in duplicate), and/or indicated stimuli. Cells were harvested after 5 to 6 days and analyzed by flow cytometry for CFSE dilution among CD4⁺ T cells (8 donors tested in duplicate). (C-D) PBMCs from healthy controls (red square), HNC patients (blue circle, 8 patients tested in duplicate), or MC patients (green triangle, 3 patients tested in duplicate) were analyzed by flow cytometry and divided into 3 separate cell populations: lymphocytes (L), monocytes (M), and low-density neutrophils (LDNs). Shown is a representative plot (C) and the percentage of cells of each indicated cell population (D). Error bars indicate SEM. *P < .05, **P < .01, ***P < .001, ****P < .0001.