Abstract

P 245

Plasmacytoid dendritic cells (PDC) in patients with acute retinal necrosis (ARN) syndrome

Bergua A.¹, Kittan N.², Haupt S.², Donhauser N.², Korn K.², Kruse F. E.¹, Schmidt B.^2
1Department of Ophthalomology, ²Institute of Clinical and Molecular Virology, Erlangen-Nürnberg University, Erlangen

Objective: The first-line recognition of viruses and virus-infected cells is mediated via the innate immune system. An important component are the plasmayctoid dendritic cells (PDC), which have been identified as major producers of type I interferons (IFN). Severe viral infections in non-immunocompromised patients may result from selective defects in the innate recognition of these viruses. Acute retinal necrosis (ARN) caused by herpes simplex virus (HSV) or varicella zoster virus (VZV) is a severe disease in otherwise immunocompetent individuals. This study aims to find a potential connection between ARN and a selective defect in the innate immunity of these patients.
Methods: 8 patients and 16 healthy controls were included into the study. Patients and controls were matched according to age and sex. Isolation of PBMC/PDC and FACS analysis from EDTA-anticoagulated blood: PBMC of patients and controls were isolated using Ficoll gradient centrifugation. PDC were purified from PBMC in a two step LS/MS column isolation procedure using the BDCA-4 cell isolation kit (Miltenyi Biotech, Bergisch-Gladbach, Germany). Both PBMC (1x106 cells) and PDC (1x104 cells) were exposed to different stimuli. FACS analysis was performed on EDTA blood to determine PDC, MDC, and NK cell counts.
Results: The amount of IFN-alpha produced by PDC after exposure to different stimuli was considerably lower in patients (0.27%) compared to controls (0,44%) (p=0.02). A PDC-decrease was found in controls while suffering respiratory infections or diarrhea. PDC were reduced in vitreous and peripheral blood. An influx of CD8+ cells and T-regulatory cells into vitreous was observed in acute episodes of ARN.
Conclusions: Non-immunocompromised patients with severe herpes virus retinitis showed both numerical and functional deficits in native immune system. This support a multifactorial model in the etiology of ARN.

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