Figure 7: SLPI inhibits production of IP3. (a) Preloading neutrophils (1 × 105/mL) with SLPI (480 nM) significantly reduced the accumulative levels of IP1 induced by fMLP (1 μM) or IL-8 (1.2 nM) activation (final reaction volume of 200 μL). Positive controls included U73122 (5 μM) and pertussis toxin (PTX, 500 ng/mL). (b) Cells remained untreated or preloaded with SLPI (480 nM), electropermeabilized in the presence or absence of 1 μM IP3 and then stimulated with fMLP (1 μM) or IL-8 (1.2 nM) for 10 sec. (c) and (d) Neutrophils were isolated from healthy individuals and the effect of SLPI (240 or 480 nM) on the cell chemotactic index induced by fMLP (1 μM) or IL-8 (1.2 nM) was determined in the presence (■) or absence (con, □) of 1 μM IP3. SLPI had no significant inhibitory effect on neutrophil chemotaxis in the presence of augmented cytosolic IP3. Each point is the mean ± S.E. ( , NS: no significant difference, and * and ** calculated by Student’s -test).