OC expression of TRAIL and its receptors. OC expression of TRAIL and its death (DR4) and decoy (DcR2) receptors was analyzed by RT-PCR (A) and Western blotting (B). Fully differentiated OCs were obtained in unfractionated as well as T-cell–depleted MM PBMC cultures (the latter following the addition of M-CSF and RANKL). The OCs generated in the absence of T cells overexpressed TRAIL DR4 receptor at both mRNA (A) and protein levels (B). On the contrary, the OCs from T-cell–depleted cultures overexpressed DcR2 at both mRNA (A) and protein levels (B). No significant difference was found in TRAIL expression. The intensity of the bands was quantified by densitometry (histograms) and normalized to GAPDH.