Affects of immunosuppression on circulating dendritic cells: An adjunct to therapeutic drug monitoring after heart transplantation

Objectives: Recent evidence emerges dendritic cells (DCs) as pharmacological targets of immunosuppressive drugs. Therefore, in this study we monitored DCs in peripheral blood to compare the effects of calcineurin inhibitors (CNI: cyclosporine, tacrolimus) and mammalian target of rapamycin inhibitors (sirolimus, SRL, everolimus, ERL) basis-immunosuppressive therapies in human heart transplanted (HTx) recipients. Methods: We compared HTx recipients which were converted from either CNI to ERL (severe renal dysfunction, n=8), or from SRL to ERL (approval of ERL for HTx, n=8) with 20 healthy human controls. Twenty four after the last CNI or SRL dose recipients were treated with ERL/BID on clays 1-3. Peripheral blood was collected at trough in the morning before and on day 4 after conversion. Percentages of positive myeloid and plasmacytoid DC (in and pDC) subsets in peripheral blood were analysed by flow cytometry. The status of maturation was further characterised by flow cytometry analysis of % expression of CD83 and % expression of various intracellular cytokines (IL-1 beta, TNF-alpha, IL-8, IL-12), respectively. Results: HTx recipients had higher % positive mDCs regardless the immunosuppressive therapy compared to controls (p < 0.05). Whereas, % positive pDCs were only significantly lower in recipients converted from CNI to ERL compared to controls (p < 0.05). The data consolidate the finding that the subset ratio pDCs/mDCs was lower in recipients compared to controls. But after conversion from CNI or SRL to ERL the ratio increased towards pDCs. Percentages of expression of CD83 on mDCs were not different among the recipient groups and controls. Recipients with CNI and SRL had higher % expression of IL-12 and lower % expression of IL-1 beta compared to controls (p < 0.05). However, after conversion to ERL% expression of both IL-12 and IL-1 beta returned to control values in both groups. Conclusions: The results showed that analysis of immunosuppression of circulating DCs in peripheral blood may be an adjunct to therapeutic drug monitoring to optimize immunosuppressive therapy after HTx. (c) 2006 Published by Elsevier B.V.