Inhibitory impact of PF-4 on CTAP-III processing by mast cells and neutrophils. Human skin MCs (1 × 104/mL) prestimulated with α-IgE (A) and human neutrophils (5 × 106/mL) (C) were incubated with 3 μM CTAP-III in the absence and in the presence of increasing dosages of PF-4 for 30 minutes at 37°C. For time-course studies, prestimulated MCs (B) and neutrophils (D) were incubated for increasing times with either 3 μM CTAP-III alone (▪) or in the presence of 4 μM PF-4 (□). To determine the amount of generated NAP-2, 2-μL samples of cell-free supernatants were subjected to SDS-PAGE, Western blotting, and immunochemical staining with rabbit antiserum Rα-βTG. NAP-2 was then quantified by Li-cor analysis against a standard of NAP-2 run in parallel (A-B). In panel A, results are given as the percentage of NAP-2 formed in the absence of PF-4. Data represent mean ± SD from 3 independent experiments with cells from different donors.
