Myelin lipophilin-induced experimental allergic encephalomyelitis in guinea pigs

Experimental allergic encephalomyelitis (EAE) is an autoimmune disease of the central nervous system (CNS). Studies have shown that the encephalitogen responsible for EAE is the basic protein (BP) found inCNS myelin and is, perhaps, the only encephalitogenic component of the CNS. Purified lipophilin, a hydrophobic lipoprotein of myelin, was tested for its ability to induce EAE in guinea pigs. Animals challenged with myelin lipophilin (in CFA) developed clinical and histological signs of EAE which were indistinguishable from those developed by animals challenged with myelin BP (in CFA). Both lipophilin and BP induced and elicited delayed type hypersensitivity in animals challenged with either antigen and the development of delayed type hypersensitivity correlated with eventual onset of clinical signs of disease. The absence of BP from the lipophilin preparation used in this study was documented by several purification procedures and chemical modification of tryptophan in lipophilin, destroyed its ability to induce EAE. These results demonstrate that myelin lipophilin is encephalitogenic and induces a cell-mediated immune disease of the CNS similar, if not identical, to BP-induced EAE. Tryptophan, which is known to be an essential residue in the BP-determinant for disease in guinea pigs, is required for the encephalitogenic activity of lipophilin.