ACTIVATION OF PLASMACYTOID DENDRITIC CELLS IN NEUROMYELITIS OPTICA PATIENTS.

Introduction: Neuromyelitis optica (NMO) is an inflammatory demyelinating disease of the central nervous system (CNS) in which lesions occur predominantly in the spinal cord and optic nerves. Since the discovery of the antibody to aquaporin-4 (AQP4), NMO has been regarded primarily as an antibody-mediated disease. The production of antibodies is dependent on various and complex mechanisms. Plasmacytoid dendritic cells (pDCs) are known for their ability to produce IFN-α, and the type I interferon contributes to the production of autoantibodies. The aim of this research was to investigate the function of pDCs in the blood of NMO patients. Materials and Methods: Twelve patients with NMO were studied. The pDCs were isolated using magnetic bead separation and the expression of indoleamine 2,3-dioxygenase (IDO) e IFN-a was determined by real time PCR. Results: Although the 12 NMO patients were under immunosuppressive treatment, the results showed that the pDCs from peripheral blood were activated and presented increased expression of IFN-α, with simultaneous low expression of IDO. Discussion and Conclusion : The production of type I interferon frequently results in the development of autoantibodies and autoimmune disease. The research results demonstrated an increased expression of IFN-α by pDCs in patients with NMO, even during treatment with immunosuppressive drugs. A low expression was also observed of IDO, responsible for the degradation of tryptophan and stimulation of regulatory T lymphocytes. These findings may explain, at least in part, the increase of anti-aquaporin-4 antibody production in this group of patients. [ABSTRACT FROM AUTHOR]