IL-4–elicited pleural eosinophils show enhanced responsiveness in vitro.

Eosinophils were purified from pleural cavities of rats injected intrapleurally with IL-4 (5000 units/100 μL per cavity, ▪) or RPMI (100 μL/cavity, ■), and their degranulation (A) and adhesive responses (B) were quantified. Panel A shows the ability of rat pleural eosinophils to release eosinophil peroxidase (EPO) in response to the calcium ionophore A23187. Enzyme release is expressed as the percentage of total enzyme in cells lysed with Triton. Panel B shows the adhesion of rat pleural eosinophils to plates coated with fibronectin or recombinant soluble vascular cell adhesion molecule 1 (VCAM-1) (both 3 μg/mL). The results are presented as the mean ± SEM value for 3 animals per group in triplicate. A significant difference from levels in RPMI-treated rats is indicated by asterisks; 1 asterisk indicatesP < .01 and 2 indicate P < .001.