BACKGROUNDAdvances in transplantation immunology show that the balance between dendritic cells (DCs) and their subsets can maintain stable immune status in the induction of tolerance after transplantation. The aim of this study was to investigate if DCs and DC subpopulations in recipient peripheral blood are effective diagnostic indicators of acute rejection following kidney transplantation.

METHODSImmunofluorescent flow cytometry was used to classify white blood cells (WBCs), the levels of mononuclear cells and DCs (including the dominant subpopulations, plasmacytoid DC (pDC) and myeloid DC (mDC)) in peripheral blood at 0, 1, 7, and 28 days and 1 year after kidney transplantation in 33 patients. In addition, the blood levels of interleukin-10 (IL-10) and IL-12 were monitored before and after surgery. Fifteen healthy volunteers served as normal controls. Patients were undertaking hemodialysis owing to uremia before surgery.

RESULTSThe total number of DCs, pDC, and mDC in peripheral blood and the pDC/mDC ratio were significantly lower in patients than controls (P < 0.05). Peripheral DCs suddenly decreased at the end of day 1, then gradually increased through day 28 but remained below normal levels. After 1 year, levels were higher than before surgery but lower than normal. The mDC levels were higher in patients with acute rejection before and 1 day after surgery (P < 0.005). There was no significant difference in IL-10 and IL-12 levels between patients with and without acute rejection.

CONCLUSIONThe changes in DCs and DC subpopulations during the acute rejection period may serve as effective markers and referral indices for monitoring the immune state, and predicting rejection and reasonably adjusting immunosuppressants.