IL-5 and z-VAD.fmk prevent phosphatidylserine externalization, but only IL-5 prevents loss of ΔΨm in eosinophils.

Freshly isolated eosinophils (0 hour) or eosinophils incubated in the absence (−IL-5) or presence of IL-5 (10⁻¹⁰ M) or z-VAD.fmk (100 μM) for 24 hours were assessed for ΔΨm and PS exposure as described in “Materials and methods.” (A) Flow cytometry histograms of 10 000 events showing percentage cells exhibiting reduced ΔΨm or increased PS exposure. At 0 hours, eosinophils were also treated with the mitochondria uncoupling agent, mCCP, as a positive control for loss of ΔΨm (open histogram, figure in parentheses). Results are representative of 6 separate experiments. (B) Percentage eosinophils with reduced ΔΨm (open bars) or PS externalization (filled bars). Results are expressed as mean ± SE of 6 separate experiments. Asterisk indicates that IL-5 and z-VAD.fmk significantly inhibited PS exposure compared with medium control (−IL-5), but only IL-5 inhibited loss of ΔΨm (P < .05).