Specifity of SN on eosinophil chemotaxis into nitrocellulose micropore filters (5-μm pore size). Maximal effective concentrations of SN (0.1 μmol/L), SP (0.1 nmol/L), or IL-8 (1 nmol/L) with or without SN-antibody (dilution 1:1,000) and anti-human IL-8 antibody (10 μg/mL), respectively, were placed in the lower wells of the chamber. RPMI 1640/0.5% BSA alone or with each antibody served as control. Thereafter 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) (left panel). In another set of experiments cells were pretreated with SN (0.1 μmol/L) for 10 minutes, washed twice, and thereafter allowed to migrate towards chemoattractants or medium (right panel). 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.