Down-regulation of MHC-expression on dendritic cells in rat kidney grafts by PUVA pretreatment

Diltiazem impairs maturation and functions of human dendritic cells

The aim of this study was to define the effects of diltiazem, a calcium antagonist drug used in cardiology and in clinical transplantation, on the differentiation and maturation of human dendritic cells (DC). Herein, we demonstrate that diltiazem, in association with granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), induces monocytes to differentiate into cells with many of the characteristic of DC. However, diltiazem-induced DC express high levels of mannose receptor and Fc gamma RII and, consequently, manifest a higher endocytic activity compared with GM-CSF+IL-4-induced DC. Importantly, diltiazem-induced DCs have an impaired responsiveness to lipopolysaccharide and CD40 ligand because they produce decreased levels of IL-12 and reveal a reduced ability to stimulate alloreactive T-cell responses as well as in inducing interferon-gamma producing Th1 cells. These effects may contribute to a decreased DC-dependent T-cell activation and may help to explain the immunoregulatory function of diltiazem and its effectiveness in preventing transplant rejection.

Effects of PUVA therapy on kidney allografts: results of a randomized prospective double-blind study

After successful experimental organ transplant studies on the efficacy of PUVA therapy combining donor pretreatment with the photosensitizer 8-methoxypsoralen (P) and the ex vivo irradiation of organs with long-wave ultraviolet light (UVA) prior to transplantation, we started in 1989 the first randomized, prospective, double-blind study to clarify the efficacy of PUVA therapy in human kidney transplantation. This study included 50 kidney donors, 25 of whom were PUVA-treated. A total of 75 kidneys were transplanted in Berlin, Halle and Rostock. The complete data of these 75 recipients were available for the final evaluation. The PUVA group (n = 36) and the non-PUVA group (n = 39) were not statistically significantly different as to donor and recipient data. Regarding the results, no differences were seen in initial hospitalization time, early graft function, rejection rate, number and time of rejection episodes. After a follow-up of 24 months, both graft survival (PUVA vs. non-PUVA: 75% vs. 71.8%) and patient survival (97.2% vs. 97.4%, respectively) were comparably high. PUVA therapy did not influence the development of vascular rejection. Interestingly, the rate of late graft loss after the 6th posttransplant month was lower, but not statistically significantly so, in the PUVA than in the non-PUVA-group (2 vs. 6 graft losses). Thus, PUVA-pretreated kidneys may be associated with a reduced development of chronic rejection.

Renal ischaemia--reperfusion injury

Ischaemia-reperfusion injury is a complex interrelated sequence of events that classically involves the vascular endothelium and activated leucocytes. During the ischaemic phase the endothelium is primed both to produce free radicals and to secrete chemoattractants. The resultant neutrophil sequestration serves to amplify the injury, but damage is not confined to the postischaemic area and more generalized effects typically follow. The situation in the kidney is complex for, while ischaemia primes the tissue for reperfusion damage, it also causes early and irreversible tubular injury. Furthermore, it appears that relatively less importance should be attached to the involvement of neutrophils than at other sites, and relatively more to a local postischaemic imbalance in the levels of nitric oxide and endothelin. Despite a greater understanding of the pathogenesis of ischaemia-reperfusion injury, effective treatment remains elusive and research is hampered by apparent species and organ-specific differences.