OPG/TRAIL complex in fresh T cells and culture media from PBMCs of patients with MM, and anti-TRAIL mAb effect on osteoclastogenesis. TRAIL and OPG were coimmunoprecititated by a mAb against TRAIL in PBMC fresh T-cell lysates and PBMC culture media. Mouse IgG was used as control, and a total T-cell lysate was also loaded. OPG was identified as a 55 kDa molecular weight band (A). PBMCs from patients with MM were cultured in the presence of an anti-TRAIL mAb at different concentrations ± RANKL. The anti-TRAIL mAb, added to the culture media in the absence of exogenous RANKL, significantly reduced osteoclastogenesis (B). Further, the addition of RANKL rescued the anti-TRAIL mAb inhibitory effect. The graph represents the mean values ± SE of a representative experiment.