The distribution of myelin basic protein in central nervous system lesions of multiple sclerosis and acute experimental allergic encephalomyelitis.

To obtain more information about early events in central nervous system myelin injury in multiple sclerosis (MS), a comparative study was conducted of the distribution of myelin basic protein (BP) in tissue lesions of both MS and experimental allergic encephalomyelitis (EAE). Sixteen postmortem specimens containing lesions from 4 persons with MS and the brains of 14 guinea pigs with acute EAE induced with BP were studied. Cryostat sections of quick-frozen material were fixed, treated with rabbit antibody to BP, and processed by immunoperoxidase techniques. The reaction of antibody to BP was reduced or absent in MS lesions but normal in uninvolved surrounding tissue. Alterations in BP generally paralleled changes in staining of myelin by histological methods. Marked diminution of reactivity with anti-BP occurred in early lesions of MS and extended far beyond any identifiable inflammatory elements. In both parenchyma and perivascular areas, lipid-laden macrophages in MS plaques frequently contained BP material in addition to a variable amount of endogenous peroxidatic activity. Compared with MS, BP was relatively well preserved in brains of guinea pigs with EAE. At the light microscopy level, normal-appearing patterns of BP existed adjacent to the perivascular cellular infiltrates, and macrophages containing BP material were rare. The results of this study suggest differences between MS and acute EAE in both removal of BP from the central nervous system and its subsequent disposal.