Moreover, an increased expression of Il-17 in herniated and degenerated lumbar intervertebral discs has been reported, indicating a possible role of this cytokine in the chronification of pain. While the innate immune Cabergoline system has been found to play an important role in acute pain, T-Lymphocytes as key players of the adaptive immune system are supposed to be of major importance in the pathogenesis of chronic pain. In patients with complex regional pain syndrome and in those suffering from abacterial chronic pelvic pain, a TH1/TH2 imbalance with increased numbers of TH1 cells has been shown. The role of both T cell Eptifibatide subsets has extensively been analyzed in tumor growth and in the development of inflammatory and autoimmune diseases. Recently published data also indicate an involvement of both T cell subsets in the development of chronic pain. For example, in patients with postherpetic neuralgia, increased Treg numbers have been found. In addition, there is evidence that these cells play a central role in endogenous recovery from neuropathic pain. Due to the antagonistic functions of TH17 and Treg cells, and in analogy to the well-known TH1/TH2 paradigm, the ratio between TH17 and Tregs is increasingly used to characterize immune responses. In CLBP, however, specific alterations in the adaptive immune system have not conclusively been analyzed, yet. In the current study, we investigated cytokine profiles and T helper cell subset compositions in CLBP patients and healthy controls. Our results indicate that CLBP is associated with characteristic alterations of T helper cell subsets: The TH17/ Treg ratio was significantly decreased. We further provide evidence that these alterations persist even in those patients exhibiting significant pain reduction after participation in a standardized multimodal therapy program. During a prospective recruitment period of two years, all patients seeking treatment for nonspecific CLBP at our pain clinic were assessed for study specific inclusion and exclusion criteria. Inclusion criteria were CLBP defined as low back pain persisting longer than two month, not attributable to a recognized specific pathological condition and planned participation in a specific 4 week multimodal outpatient program.