Figure 6.

Blocking tumour necrosis factor-related apoptosis-inducing ligand (TRAIL), DNAX accessory molecule 1 (DNAM-1) or leucocyte function-associated antigen 1 (LFA-1) promotes osteoclast-mediated bone erosion in a co-culture of osteoclasts and natural killer (NK) cells. Enriched osteoclasts were seeded on bone slices at 5 × 10⁴/well, autologous interleukin-15 (IL-15) -activated NK cells were added the following day at an effector : target ratio of 1 : 1 and co-cultured for 3 days in the presence of the blocking monoclonal antibody (mAb) of interest. Survival of active osteoclasts was quantitatively measured by bone degradation, C-terminal type I collagen fragments (CTX-I), in the conditioned media. (a) Osteoclasts and IL-15-activated NK cells were co-cultured with blocking mAb as described. The results are shown for independent experiments of n = 8 donors. (b) NK cells and osteoclasts were co-cultured with different concentrations of blocking mAbs at 0·1 μg/ml, 1 μg/ml and 5 μg/ml (or 10 μg/ml). Data shown is obtained from n = 4 donors. (c) Bone slices were stained with haematoxylin and resorption pits were quantified using an Immunospot Image Analyser. Images and graphs represent the results of experiments performed with n = 4 donors. *P < 0·05; **P < 0·01.