Fig. 1

Photographs of the animals and histological pictures of the accumulation of IgG in the spinal MNs of inoculated mice and from human autopsy samples. a The accumulation of ip administered ALS IgG in the spinal MNs of mice (one is indicated by an arrow) detected by direct immunohistochemistry with FITC-labeled antibody reacting with human IgG. Fluorescence picture. The bar indicates 30 μm for each picture: (a–c). b The accumulation in the spinal MN of a mouse of ip inoculated IgG from a goat immunized with the homogenate of the ventral horn of the bovine spinal cord, visualized with FITC-labeled anti-goat IgG. Direct immunohistochemistry. Both the MNs and the cell processes contain goat IgG, and the external membrane of the MNs is immunostained (indicated by an arrow). c Slight IgG immunoreactivity in the spinal MNs of mice (one is indicated by an arrow) after the ip inoculation of normal human IgG. d The mouse on the left was inoculated with IgG obtained from the deceased sALS patient whose spinal cord is shown in (e). The body posture of the animal appears unusual, reflecting some decrease in muscle strength, but obvious paresis did not develop. The mouse on the right was completely paralyzed after the ip injection of IgG from a goat with EAGMD. e Immunohistochemical picture of the ventral horn MNs from the lumbar region of the spinal cord of a patient who died of ALS. IgG accumulation can be detected in granular form in the cytoplasm of the MNs with peroxidase-labeled anti-human IgG as a dark reaction product. (One is indicated by the arrow.) The bar represents 60 μm. f The spinal MNs from autopsy sample of the lumbar spinal cord of a patient without CNS disease exhibits minimal immunostaining for human IgG with the same immunohistochemical reaction as in (e) (arrow)