Deficient activation of microglia during optic nerve degeneration.
Transection of an optic nerve (ON) is followed by slow removal of myelin. We studied microglia for the expression of molecules that characterize activated myelin phagocytosing macrophages: MAC-1, Fc gamma II/III receptor (FcR), MAC-2 and F4/80. In-vitro, microglia expressed all molecules and phagocytosed myelin. In-vivo, intact ON displayed high levels of MAC-1, little FcR and F4/80, and no MAC-2. The expression of these molecules was upregulated differentially in in-vivo degenerating ON: MAC-1 uniformly, FcR and F4/80 variably, and MAC-2 sporadically. The distribution of MAC-2 expression correlated best with a pattern of sporadic structural degeneration. Thus in-vivo, ON injury is followed by deficient microglia activation, which we suggest contributes significantly to the slow clearance of myelin.
Department of Anatomy and Cell Biology, Hebrew University Hadassah Medical School, Jerusalem, Israel.
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Reichert
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Rotshenker
D000818:Animals; D000943:Antigens, Differentiation / Q000378:metabolism; D002478:Cells, Cultured; D019084:Fluorescent Antibody Technique, Indirect; D037502:Galectin 3; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D007111:Immunity, Cellular; D016177:Macrophage-1 Antigen / Q000378:metabolism; D008264:Macrophages / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000276:immunology*; D009186:Myelin Sheath / Q000276:immunology; D009410:Nerve Degeneration / Q000276:immunology*; D009900:Optic Nerve / Q000276:immunology*; D010587:Phagocytosis; D017452:Receptors, IgG / Q000378:metabolism
D000943:Antigens, Differentiation; D037502:Galectin 3; D005904:Glial Fibrillary Acidic Protein; D016177:Macrophage-1 Antigen; D017452:Receptors, IgG; C036763:monocyte-macrophage differentiation antigen