Figure 2.

Effects of protease inhibitors on EPC release from activated eosinophils. Eosinophils (1×10⁶ cells ml⁻¹) were preincubated with medium, chymostatin, leupeptin or E64-d at 1×10⁻⁶ M for 15 min at 37°C and ECP release was induced with (a) IgG beads (2.5 mg ml⁻¹ beads) plus rIL-5 (10 ng ml⁻¹) after a 4 h incubation or with (b) PAF (1×10⁻⁷ M) or (c) calcium ionophore A23187 (1×10⁻⁷ M) after a 15 min incubation. The amount of ECP released into the medium was assayed with an ECP RIA kit. Values are expressed as means±s.d. of triplicate samples per assay from eight different donors. The total cellular ECP in eosinophils (405 ng per 1×10⁶ cells) was determined and values were expressed as percentages of the total cellular ECP concentration. Chymostatin produced a significant reduction in ECP release (^*P<0.01). Data were analysed by Student' t-test and the range of basal ECP release into the medium under conditions of no pretreatment and no stimulation was 8–12 ng l⁻¹. (n=8).