Study About The Correlation Of The DPIV Enzyme Activity And Anti-CD26/DPIV Antibody With Sj(?)gren's Syndrome

Dipeptidyl peptidase IV (CD26/DPIV) is a 110-KDa cell-surface glycoprotein with diverse functions, it was expressed in a variety of tissues and cells, including epithelial cells and selected leukocyte substrates. At the resting state in the peripheral blood, CD26/DPIV was preferentially expressed on the helper/memory T cell population. DPIV cleaves X-Pro dipeptides from the NH2-terminus of a large variety of proteins. The expression of CD26/DPIV was tightly regulated on human T lymphocytes. Recent studies have demonstrated that CD26/DPIV cleaved a number of cytokines and chemokines such as IL-1β,IL-2,TNF-β, and altered their biological functions by altering their chemotactic potency, impairing their signaling effects, and modifying their receptor specificity. We also demonstrated that CD26/DPIV interacted physically and functionally with several molecules which played an important role in T cell function. It was co-modulated on the T cell surface with CD45, a membrane-linked tyrosine phosphatase which was critical to T cell signal transduction, the other molecules that combined with CD26/DPIV were the ADA and M6P/IGFIIR. CD26/DPIV was functionally associated with T cell signal transduction processes which were capable of transmitting signals to T cell activiation. Analysis of serum DPIV activity has been shown to be relevant to the activity of the membrane bound enzyme on normal T lymphocytes, it was also suggested that the serum CD26/DPIV originated from T lymphocytes. Recent studies have demonstrated that CD26/DPIV played a role in autoimmune diseases and other immune-mediated disorders such as SLE,RA,SS,AIDS, etc. but the conclusions were argureable. Sj?gren's syndrome (SS) was an autoimmune disorder characterized by lymphocytic infiltrates and destruction of the salivary and lacrimal grands, and sysmetic production of autoantibodies including anti-SSA antibody and anti-SSB antibody .SS may occur in a variety of connective tissue diseases, such as RA,SLE, etc. SS have two types, primary and secondary SS, however the pathogenesis of this syndrome remains unclear. To determine the role of soluble CD26/DPV in the pathophysiology of patients with SS, we studied on the DPIV enzymatic activity and the presence of anti-CD26/DPIV antibody in the sera of patients, and we also analyzed the relationship between the DPIV activity and various antibodies. The results showed that the specific activity of serum DPIV enzyme decreased and anti-CD26/DPIV antibody presenced in the serum, moreover anti-SSB antibody and anti-CD26/DPIV antibody were associated with the DPIV activity. In summary, our study suggested that the decrease of DPIV activity in the sera of SS patients could be associated with the production of anti-SSB antibody and anti-CD26/DPIV antibody, it may be involved in the pathophysiology of SS and appeared to be useful as a new disease activity measure of SS.