751. Microvascular and cellular responses in the optic nerve of rats with acute experimental allergic encephalomyelitis (EAE).
- Author
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Hu P, Pollard J, Hunt N, Taylor J, and Chan-Ling T
- Subjects
- Animals, Blood-Brain Barrier drug effects, CD4-Positive T-Lymphocytes immunology, CD8-Positive T-Lymphocytes immunology, Coloring Agents, Encephalomyelitis, Autoimmune, Experimental chemically induced, Encephalomyelitis, Autoimmune, Experimental immunology, Histocompatibility Antigens Class II metabolism, Horseradish Peroxidase, Immunohistochemistry, Indoles, Lymphocyte Subsets immunology, Macrophages immunology, Male, Microcirculation pathology, Microglia metabolism, Monocytes immunology, Myelin Basic Protein pharmacology, Myelin Sheath pathology, Optic Nerve immunology, Optic Nerve metabolism, Organometallic Compounds, Rats, Rats, Inbred Lew, Receptors, Antigen, T-Cell, alpha-beta immunology, Time Factors, Blood-Brain Barrier physiology, Encephalomyelitis, Autoimmune, Experimental pathology, Optic Nerve blood supply, Optic Nerve pathology
- Abstract
The optic nerve of rats with EAE was examined at various times to determine the integrity of the blood-brain barrier (BBB) and to assess monocyte-macrophage, T cell, and microglial responses. In naive control animals, leakage of horseradish peroxidase (HRP) and the presence of cells expressing major histocompatibility complex (MHC) class II antigen were evident in the meninges of the retrobulbar optic nerve. In rats with EAE, microglia in the region of the lamina cribrosa and in the regions adjacent to the meninges became activated from day 7 to 8 postinduction (pi). HRP leakage was also evident in the region of the lamina cribrosa from day 7 to 8 pi. On day 8 pi, infiltration of inflammatory cells and Monastral blue leakage were apparent in the myelinated region of the optic nerve. The intensity of these cellular and vascular changes peaked at day 12 pi, when signs of clinical disease became manifest. Monocytes-macrophages expressing MHC class II and the ED1 antigen, together with lymphocytes expressing the alphabetaT cell receptor, constituted the major proportion of cells associated with inflammatory lesions. Thus: (i) the inherent weakness of the BBB as well as the presence of both antigen (myelin) and MHC class II+ cells in the retrobulbar optic nerve are likely susceptibility factors for the frequent involvement of this region in EAE and multiple sclerosis; and (ii) activation of microglia occurs early in the pathogenesis of experimental optic neuritis.
- Published
- 1998
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