<qa>  What is the effect of anti-TNF therapy on the number of osteoclast precursorsOsteoclastic bone resorption depends on both the capacity to generate osteoclasts osteoclastogenesis and on individual osteoclast activity. The investigators objective is to study the effect of anti-TNF therapy on the number of osteoclast precursors in the peripheral blood of patients with Rheumatoid Arthritis, on in vitro osteoclastogenesis and on osteoclast activity before and during the treatment of patients with Rheumatoid Arthritis with Adalimumab. 