 Osteoclastogenesis: PBMCs will be isolated from 50 ml of blood by Ficoll-Hypaque gradient and the number of CD14 OC precursors will be determined by FACS. The whole population of PBMCs will be plated in 48-well tissue culture plates containing a bone slice or a glass slide, and the cells will be allowed to differentiate for 21 days in the presence of recombinant RANKL 75 ngml and M-CSF 10 ngml. The cells are then fixed and stained for TRAP activity and with hematoxylin. The number of TRAP cells containing three or more nuclei will be counted in each well. Triplicates will be used for each patient. In parallel wells the cells will be incubated in the same conditions but in the presence of Adalimumab in concentration comparable to that found in vivo after treatment. 