Figure 5.

Blocking tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), DNAX accessory molecule 1 (DNAM-1) or leucocyte function-associated antigen 1 (LFA-1) decreases lysis of osteoclasts by interleukin-15 (IL-15) -activated natural killer (NK) cells. Osteoclasts and autologous NK cells were generated and cultured as described. Enriched osteoclasts were seeded at 5000 cells/well in a 96-well plate and labelled with ⁵¹Cr after 24 hr. (a) IL-15-activated NK cells were pre-incubated with the blocking monoclonal antibody of interest for 2 hr at 37° before co-culturing with ⁵¹Cr-labelled osteoclasts at an effector : target ratio of 10 : 1 as described. Experiment carried out with n = 7 donors. Statistical significance is calculated in relation to cells incubated with corresponding isotype-matched control immunoglobulin. (b) IL-15-activated NK cells were co-cultured with osteoclasts at different effector : target ratios with specific blocking mAb (solid lines) or corresponding isotype (dotted lines), to measure the release of ⁵¹Cr from the killed osteoclasts. Figures are representative of n = 7 donors, and experiments were performed in triplicate. The data are analysed with two-tailed, unpaired Student's t-test. *P < 0·05; **P < 0·01; ***P < 0·001.