In recent years, a population of CD4 + T lymphocytes, Tfh (T follicular helper cells) has been demonstrated and seems likely to play an important role in the pathogenesis of rheumatoid arthritis. Physiologically these cells were initially described in the secondary lymphoid organs where they are essential for the survival and differentiation of B lymphocytes into antibody-secreting cells. More recently, they have been described in the blood (c Tfh for circulating T follicular helper cells) and appear to be a reflection of Tfh activity in tissues.