Crystals, paracrystals, and rigid tubules in multiple sclerotic brain and spinal fluid

Brain and spinal fluid were obtained post mortem from an individual with multiple sclerosis who died following carbon monoxide inhalation. Electron microscopic examination of the plaque region revealed a crystalline structure (repeat unit 380 to 410 A) within rough endoplasmic reticulum of astrocytes, a paracrystal (160 to 220 A) within the cytoplasm of astrocytes, and rigid tubules (outer diameter 320 to 450 A) within a cell in the lumen of a capillary. The paracrystal was enclosed by the glial fibrils. A second crystalline material was observed within cells in the 15,000 X g pellet from spinal fluid. The ultrastructural pattern of this second crystal was generated by three sets of parallel lines; a given set was intersected by the other two sets. The crystal had only two different repeat units (410 to 450 A; 310 to 350 A) since the smaller dimension was common for two sets of lines. The two crystals were large; the one in astrocytes had a length of 52,000 A and that in spinal fluid sediment was 62,000 A. These structures were observed in the one multiple sclerotic brain obtained at autopsy but were not detected in multiple sclerotic brains that had been frozen for extended periods. Plaque regions and grossly normal white matter were homogenized and the 1000 X g supernatant of this material was fractionated in a continuous CsCl-sucrose density gradient. Long tubules (320 to 500 A diameter) were observed in the 1.24 to 1.26 density region. The major proteins of the 1.24 to 1.26 fraction had molecular weights clustered at 40,000 to 45,000, 88,000 to 130,000, and 300,000.