Fig. 2: Alb activates hHv1 in human neutrophils to increase ROS production and elastase release.

a Proton currents passed by hHv1 in human neutrophils studied in the absence (left) and presence (middle) of 450 μM Alb (steps from −60 and +60 mV in 20 mV increments). Fitting activation and deactivation of currents at +60 mV offered time constants (Supplementary Table 1). Right, hHv1 currents measured at the peak of a test pulse to +60 mV after exposing neutrophils to 450 μM Fab (white bar), 450 μM Alb (gray bar), or 450 μM Alb + 20 μM C6 (red bar). Values are normalized to mean current amplitude in the absence of Alb. C6 peptide blocked 87 ± 2% of of the current activated by Alb, n = 3 cells. b Left, effect of fMLF alone or in combination with Alb on ROS production by human neutrophils. Human neutrophils (2 × 10⁵ cells) were incubated without or with 450 μM Alb, then stimulated with 1 μM fMLF. ROS was measured using luminol (relative light units, RLU). ROS production from unstimulated neutrophils is negligible (white circles). Alb (gray circles) enhanced and sustained the fMLF-stimulated ROS production compared to neutrophils stimulated with fMLF alone (black circles). Incubation with 20 μM C6 (red circles) inhibited ROS production potentiated by 450 μM Alb. Right, ROS produced 60 min after fMLF stimulation. Incubation with Alb increased ROS production by human neutrophils (gray bars); addition of C6 (20 μM, red bar) inhibited the ROS production potentiated by 450 μM Alb. 450 μM Fab had no effect on fMLF-stimulated ROS production (white bar). Values are normalized to mean ROS production by neutrophils stimulated with fMLF alone, n = 3 independent experiments. c Human neutrophils (2 × 10⁵ cells) were incubated without (black circles) or with 450 μM Alb (gray circles) and then stimulated with increasing concentrations of fMLF. ROS were measured as described in (b). Some error bars are smaller than symbols, n = 3 independent experiments. d Human neutrophils (6 × 10⁵ cells) were incubated with Alb and then stimulated with 1 μM fMLF. Total elastase release at each test condition was measured spectrophotometrically. The values are normalized to elastase release stimulated with fMLF alone (Control, white bar). A 450 μM Alb increased the elastase release by neutrophils (gray), and the increase was inhibited by 20 μM C6 (red) whereas 450 μM Fab had no effect on fMLF-stimulated elastase release (white bar), n = 3 independent experiments. Values are mean ± SEM. Source data are provided in the Source Data file.