Figure 4.

Both extracellular and endogenous PBEF contribute to the inhibition of neutrophil apoptosis. (A) Polyclonal anti-PBEF Ab (1:500) added to the culture medium neutralized the antiapoptotic effects of recombinant PBEF/GST, but in contrast to the effects of inhibition of PBEF translation with antisense, oligonucleotide did not block the antiapoptotic effects of LPS; n = 4, *P < 0.05 versus controls. (B) Anti-PBEF Ab (1:500), however, significantly blocked the inhibitory activity of conditioned medium (CM) from LPS-treated neutrophils. Mean ± SD, n = 3, *P < 0.05 versus controls, **P < 0.05 versus conditioned medium alone (no anti-PBEF Ab added). (C) While antisense pretreatment prevented the inhibitory effects of LPS exposure, addition of inhibitory concentrations of rPBEF/GST was unable to restore the inhibitory effect, suggesting that inhibition of apoptosis requires both extracellular and intracellular or endogenous PBEF; n = 3.