Effects of enzyme blockers on eosinophil chemotaxis into nitrocellulose micropore filters (5-μm pore size). Eosinophils remained untreated or were treated for 30 minutes at 37°C (humidified atmosphere 5% CO₂) with staurosporine (10 ng/mL), tyrphostin-23 (10 ng/mL) (left panel), WTN (10 nmol/L), or IBMX (1 μmol/L) (right panel). After washing twice, 50 μL of human eosinophils at 1 × 10⁶ cells/mL were added to the upper wells and were allowed to migrate for 60 minutes at 37°C (humidified atmosphere; 5% CO₂) toward chemoattractants or medium control. After fixing and staining of the filters migration depth was quantified microscopically. Data are expressed as mean ± SEM of the “Chemotaxis Index,” which is the ratio between the distance cells migrate toward test substances and that toward control medium. n = 6. Statistical analyses: Mann-Whitney U-test after Kruskal Wallis analysis of variance (P < .01); n.s., not significant; *, P< .05; **, P < .01.