Effects of hBDs on neutrophil apoptosis. Neutrophils (10⁶ cells/mL) were incubated at 37°C for 18 h in RPMIFBS in the absence (Control) or presence of hBD-1, -2, -3, and -4 (1, 5 and 10 μg/mL), or LL-37 (1 and 5 μg/mL). Neutrophils were also incubated at 4°C for 18 h in the absence of hBDs or LL-37 (Resting). After incubation, neutrophil apoptosis was quantitated and expressed as a percentage of apoptotic cells. Data are the mean ± SD of 3 to 25 separate experiments. Values are compared between the incubation at 37°C in the absence (Control) and presence of hBDs or LL-37. ***.