Immunological basis for the use of TNFalpha-blocking agents in ankylosing spondylitis and immunological changes during treatment.

TNFalpha is expressed in high amounts at the site of inflammation in ankylosing spondylitis, which provided the basis to initiate treatment studies with TNF-blocking agents. We could show that the immunological effects of infliximab and etanercept differ in patients with AS, although the clinical effect was similarly good. While infliximab induced a downregulation of the production of the T-helper 1-cytokines IFNgamma and TNFalpha, etanercept treatment triggered rather an upregulation of these cytokines secreted by T cells after in vitro stimulation.