Neutrophils respiratory burst is not impaired under cyclosporine treatment following liver transplantation.

Abstract

Polymorphonuclear neutrophils (PMNs) may serve immunoregulatory and effector roles in different limbs of the immune response to infection. Superoxide production by PMNs under cyclosporine therapy after kidney transplantation is impaired (1). We investigated whether the respiratory burst (RB) of PMNs in patients undergoing cyclosporine treatment after orthotopic liver transplantation is depressed similarly. After ethics committee approval, blood samples were obtained from healthy blood donors (n=10) and from liver allograft recipients (n=10) who had been treated with cyclosporine and prednisolone. Only patients without clinical signs of infection or rejection and with a stable cyclosporine trough level between 180–240 ng/ml were included. The quantity of superoxide anion formed intracellularly during RB was determined by oxidation of nonfluorescent dihydrorhodamine to fluorescent rhodamine (2). The RB was induced by either phorbol-myristate-acetate (PMA), Escherichia coli, or priming with recombinant tumor necrosis factor alpha (TNF-α) followed by N-formyl-methionyl-leucyl-phenylalanine (FMLP) stimulation. Prestimulation of neutrophils quantified by negative controls was <5% in all samples; neutrophils’ RB (mean±standard deviation %) was ascertained at an average of 5000 vital cells per measurement. The results were expressed as a percentage of stimulated PMNs compared with the negative controls. No differences could be found between the percentage of superoxide anion-producing PMNs from healthy blood donors after stimulation with PMA (73.9±19.9%), E. coli (47.6±19.9%), and TNF-α/FMLP(47.4±14.7%) compared with those from liver allograft recipients after activation with PMA (71.6±17.8%), E. coli (57.2±14.8%), or TNF-α/FMLP (58.2±16.9%) (Fig. 1). Figure 1: Percentage of activated neutrophils producing superoxide anions during the respiratory burst after stimulation with PMA (73.6±19.2; 72.0±18.7), E. coli (47.6±19.9; 57.2±14.8) or TNF-α/FMLP (47.4±14.7; 58.2±16.9) in healthy blood donors and liver allograft recipients (n=10, mean±SD %).In the early stage of bacterial and fungal infections, PMNs play a decisive role in the nonspecific cellular immune defense. In addition to adherence, chemotaxis, migration, and phagocytosis, the functions of PMNs include an oxygen- and energy-consuming process, the so-called RB. After activation, this nicotinamide adenine dinucleotide phosphate-dependent enzyme reaction leads to the production of oxygen radicals which denature the phagocytized micro-organisms (3). The clinical importance of the formation of oxygen radicals manifests itself clearly in those patients with chronic granulomatosis. Because of a defect of the NADPH-oxidase, this disease leads to a disturbance in the production of oxygen radicals and, consequently, to life-threatening bacterial infections (4). Cyclosporine, predominantly used as immunosuppressive drug following organ transplantation, inhibits FMLP and PMA-induced superoxide anion formation in kidney-transplantation undergoing chemoluminescent analysis (1). We used flow cytometric analysis, which, in contrast to chemoluminescent analysis, allows the determination of intracellular enzyme activity after dead/alive discrimination, and moreover, is cellgroup specific. In a previous in vitro investigation, we found an approximate inhibition of neutrophils’ RB of 25% (P <0.001) under 10-fold therapeutic cyclosporine concentrations (2000 ng/ml) (5). We now could demonstrate that superoxide production is not impaired under cyclosporine treatment after liver transplantation. K. Jaeger1 Heine D. Scheinichen E. R. Kuse