Functional immune assay using interferon-gamma could predict infectious events in end-stage kidney disease.

BACKGROUND: Infections remain the second most common cause of death in patients with end-stage kidney disease (ESKD). We aimed to evaluate non-specific cell-mediated immunity in an ESKD cohort using a functional assay applicable to routine use, QuantiFERON-Monitor (Qiagen), and assess whether it can predict infectious events. METHODS: In this prospective study, we performed the QuantiFERON-Monitor test in 80 subjects including 54 patients with ESKD. QuantiFERON-Monitor is based on the measurement of plasma interferon-gamma (IFN-γ) after stimulation of NK-cells with a TLR-7 agonist, and T-cells with a TCR agonist. Patients were subsequently followed for 6 to 12 months. RESULTS: QuantiFERON-Monitor showed lower stimulated IFN-γ production in ESKD patients (n = 54) compared to healthy donors (n = 19) (p < 0.0001) and to chronic kidney disease stage 3-4 patients (n = 7) (hemodialysis (n = 30): p < 0.01; peritoneal dialysis (n = 13): p = 0.03 and ESKD on conservative management (n = 11): p < 0.001). No significant difference in stimulated IFN-γ production was observed between ESKD patients with renal replacement therapies or conservative management. Stimulated IFN-γ production was significantly lower in patients later developing infections (13.9 [5.5-48.3] IU/mL vs 85.8 [35.5-236] IU/mL, p = 0.007). Using ROC analysis, we identified a cutoff value of 63.55 IU/mL (sensitivity = 80.95%, specificity = 79.17%, AUC = 0.78, p = 0.008) to discriminate patients at higher risk of infections. Patients with stimulated IFN-γ levels measured by QuantiFERON Monitor below 63.55 IU/mL (n = 21) had a hazard ratio of 10.71 ([3.68-31.13], p < 0.0001) for the development of subsequent infections. CONCLUSION: Monitoring of IFN-γ production after stimulation of innate and adaptive immunity may identify ESKD patients with high risk of infection. This allows for therapeutic interventions to restore cellular immunity, thereby minimizing both infections and rejections after kidney-transplantation.

Preparation of the Full Set of Recombinant Mouse- and Human-Secreted Phospholipases A2.

A family of 14-20kDa, disulfide-rich, calcium-dependent secreted phospholipases A2 (sPLA2s) that release fatty acids from the sn-2 position of glycerophospholipids can be found in mammals. They have a diverse array of tissue distribution and biological functions. In this chapter we provide detailed protocols for production of nearly all of the mouse and human sPLA2s mainly by expression in bacteria and in vitro refolding or by expression in insect cells. High-resolution mass spectrometry and enzymatic assays were, respectively, used to show that all disulfides are formed and that the enzymes are active, strongly suggesting that each sPLA2 was prepared in the structurally native form. The availability of these proteins has allowed kinetic studies to be carried out, to prepare highly selective antisera, to screen for selective inhibitors, to study receptor binding, and to study the action of each enzyme on mammalian cell membranes and their in vivo biological roles.