FIG 4.

F. alocis stimulation of secretory vesicle and specific granule exocytosis is p38 MAPK dependent. Neutrophils were left unchallenged (basal), challenged with fMLF (300 nM, 5 min), challenged with F. alocis (MOI of 10, 30 min), or pretreated for 30 min with SB203580 followed by F. alocis challenge (SB + F. alocis). (A to D) Secretory vesicle and specific granule exocytosis were determined by the increase in plasma membrane expression of the CD35 or CD66b marker, respectively, by flow cytometry. Data are expressed as the mean channel of fluorescence (mcf) ± SEM from 5 independent experiments. (E and F) Supernatants from all of the different experimental conditions were collected, and the release of albumin or lactoferrin to determine secretory vesicle or specific granule exocytosis, respectively, was measured by ELISA. Data from albumin or lactoferrin release are expressed as means ± SEM in ng/4 × 10⁶ cells from 5 independent experiments for albumin and 6 independent experiments for lactoferrin.