Bcl-xL antisense but not scrambled oligodeoxynucleotides partially inhibit cytokine-mediated rescue of spontaneous eosinophil apoptosis. (A) Eosinophils lost the expression of Bcl-xL protein after in vitro culture for 24 hours (see Fig 2B). In these cells, IL-5–induced Bcl-xL expression within 24 hours (total cell culture time: 48 hours). Whereas scrambled Bcl-xL oligodeoxynucleotides (sc Bcl-xL) had no effect on IL-5–mediated upregulation of Bcl-xL protein levels, no significant induction of Bcl-xL protein expression was observed in eosinophils treated with Bcl-xLantisense molecules (as Bcl-xL). The same data were observed using GM-CSF to upregulate Bcl-xL protein expression (not presented). This figure is representative of five independent experiments. (B) Bcl-xL antisense but not scrambled oligodeoxynucleotides partially inhibited the effects of GM-CSF and IL-5 on eosinophil viability (*; P < .001). In addition, no significant effects of the oligodeoxynucleotides on spontaneous eosinophil death were observed (not presented). Means ± SEM of six independent experiments are presented. (C) Bcl-xL antisense and scrambled oligodeoxynucleotides-treated eosinophils were cultured in the presence of IL-5 as described in Materials and Methods for a total of 48 hours. Cells were stained with Giemsa-May-Grünwald (Diff-Quik). Apoptotic eosinophils are characterized by reduced cell volume as well as nuclear condensation. Some cells demonstrate secondary necrosis (lower panel, the two cells in the right margin; these cells show complete nuclear fragmentation). In these experiments, we did not observe any cell death that was the result of primary necrosis. The Bcl-xL antisense-treated cell populations demonstrated much more apoptosis. Data are representative of three independent experiments.
