A novel model of demyelinating encephalomyelitis induced by monocytes and dendritic cells

Local inflammation may be a precipitating event in autoimmune processes. In this study, we demonstrate that regulated influx of monocytes and dendritic cells (DC) into the CNS causes an acute neurological syndrome that results in a demyelinating enceplialomyelitis. Expansion of monocytes and DC by conditional expression of Flt3 ligand in animals expressing CCL2 in the CNS promoted parenchymal cell infiltration and ascending paralysis in 100% of the mice within 9 days of Flt3 ligand induction. Depletion of circulating monocytes and DC reduced disease incidence and severity. Unlike the classical models of experimental autoimmune encephalomyelitis, depletion of CD4⁺ and CD8⁺ T cells did not affect disease induction. T cells and demyelinating lesions were observed in the CNS at a later stage as a result of organ-specific inflammation. We propose that alterations in the numbers or function of monocytes and DC coupled to dysregulated expression of chemokines in the neural tissues, favors development of CNS autoimmune disease.