Identification of the encephalitogenic epitopes of CNS proteolipid protein in BALB/c mice

It was previously shown that BALB/c mice were susceptible to experimental autoimmune encephalomyelitis induced by immunization with proteolipid protein (PLP). To determine the encephalitogenic epitopes of PLP in BALB/c mice, mice were immunized with successively smaller pools of 20-mer peptides spanning the PLP molecule from amino acid 30 to amino acid 206. Immunization with PLP_180-199 resulted in clinical EAE in 9/15 mice (mean max clinical score of 3.3), and immunization with PLP_185-206 induced clinical EAE in 7/21 BALB/c mice (mean maximum score of 3.7). No relapses in disease were observed. No EAE was observed in BALB/c mice immunized with PLP_185-199 (n=15), PLP_178-191 (n=13) or other regions of PLP (n=15). Passive transfer of PLP_180-199-primed lymph node cells into naïve BALB/c mice resulted in EAE (2/2 mice, max score of 4.0). One-micron toluidine blue stained sections from the spinal cord of EAE-affected BALB/c mice revealed features typical of EAE in other strains, including mononuclear cell infiltration, myelin loss, and axonal loss.