Defective granule mobilization by FHL-5 neutrophils. Degranulation of neutrophils was examined in 1- day-old blood of healthy adults (n = 11) and fresh cord blood (n = 6) of healthy adults; and in fresh blood of FHL-5 patient A, 1-day-old blood in patient B, and 1-day-old blood in patient C. This was done by monitoring the release of (A) lactoferrin (specific granules) and surface exposure of (B) CD66b (secretory, tertiary, and specific granules) on stimulation with PAF/fMLF, and the release of (C) elastase (azurophilic granules) and surface exposure of (D) CD63 (azurophilic granules) on stimulation with cytoB/fMLF, respectively. Concentrations (ng/mL) of released factors, or the mean fluorescence intensities of surface markers for stimulated (white, blue, green, red) and unstimulated (black parts of the bars) cells are shown. The values shown are averages ± SEM from at least 2 independent experiments, each performed in triplicate, with the exception of patient A, who was evaluated once; *, P < .05; n.s., nonsignificant; Grubbs outlier test. Note that granule release is essentially absent in all 3 patients.