Time course of leukocyte accumulation induced by injection of recombinant rat interleukin 4 (IL-4) into rat pleural cavities.

Rats were injected intrapleurally with IL-4 (5000 units/100 μL per cavity; ▪) or RPMI (100 μL/cavity; ■), and leukocyte migration into the pleural cavity was quantified at different times after the injection. Results are expressed as the number of cells × 10⁶ per cavity and presented as the mean ± SEM value for 3 or 4 animals. A significant difference from levels detected in RPMI-treated animals is indicated by asterisks; 1 asterisk indicates P < .01 and 2 indicateP < .001.