[Regulatory cytokines in the response to the allogeneic renal transplant]

The outcome of the kidney allograft mainly depends on the immune response and on its complex regulation, where the cytokine network and other mediators play an important role. At present, kidney biopsy is the most useful tool for monitoring the transplant rejection and the diagnosis of the associated nephropathies, in spite of the invasiveness of the procedure. Thus, it is of great interest to find alternative tools for diagnosis. The evaluation of regulatory cytokines is a simple procedure of low cost that could be useful to increase the sensitivity of the detection of polymorphic differences, to predict the graft acceptance and for the early detection of rejection. Recent studies suggest that the high production of pro-inflammatory mediators, such as Th1 cytokines, could be detrimental, whereas the production of anti-inflammatory regulatory cytokines, such as interleukin (IL)-10 and tumor necrosis factor (TGF)-beta, could be beneficial for graft survival. In the early stages, the cellular cytotoxicity is activated by the Th1 response and the detection of cytotoxic molecules is associated to the acute rejection. Later, the balance between pro and anti-inflammatory mediators and the regulation of their levels could be more important. In this regard, TGF-beta is also fibrogenic and a high local production can contribute to kidney damage. On the other hand, the increased production of IL-10 in response to the allogeneic stimuli could be, in most cases, an important marker of long-term acceptance.