Histochemistry of Myelin. Xiii Digestion of Basic Protein Outside Acute Plaques of Multiple Sclerosis

Plaques of multiple sclerosis from a patient with a short clinical history were investigated by qualitative and quantitative histochemical methods. One of three plaques examined showed perivenous lymphocytic infiltration; this plaque was regarded as a particularly early acute lesion. In this plaque a relatively wide zone of diminished staining for basic protein extended outwards around the edge of the lesion. A narrower and irregular zone of diminished cerebroside staining was also seen around the plaque. Staining for phosphoglycerides and cholesterol was relatively normal up to the edge of the lesion; no zone of reduced staining for these lipids was seen outside the plaque. Proteolytic activity was increased throughout the lesion (pH 3.5 > 7.4). The two less acute plaques showed no obvious loss of basic protein and cerebroside outside the plaque. Addendum: Two further acute plaques of multiple sclerosis obtained recently, showed a similar loss of basic protein outside of lesion.