INDUCTION OF EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS BY MYELIN PROTEOLIPID-PROTEIN-SPECIFIC T-CELL CLONES AND SYNTHETIC PEPTIDES

Proteolipid protein (PLP) is the major protein of central nervous system (CNS) myelin. SJL(H-2s) mice immunized with a synthetic peptide corresponding to PLP residues 139-151 (HSLGKWLGHPDKF) develop acute experimental allergic encephalomyelitis (EAE). In the present study a T cell line and 4 clones were derived from SJL/J mice following immunization with this synthetic peptide. Severe clinical and histological EAE could be induced by adoptive transfer of the peptide-specific T cell line and 3 of 4 T cell clones. The T cell line/clones all responded strongly to PLP peptide 139-151 in in vitro proliferative assays. However, two different reactivity patterns emerged when truncated PLP peptides 141-150 and 141-149 were tested, suggesting that more than 1 epitope may be present within the PLP 139-151 determinant. To evaluate the encephalitogenic potential of the truncated peptides, we compared the ability of 2 truncated PLP peptides to induce EAE in vivo and proliferative responses in vitro. Immunization with PLP peptide 141-150 induced acute EAE in about 70% of mice tested, but PLP peptide 141-149 induced a comparatively mild form of EAE in 4 out of 9 mice tested. Lymph node cells from mice immunized with these peptides showed in vitro proliferative responses to each of the peptides, but the response to peptide 139-151 was always strongest. These combined in vivo and in vitro data further define the epitopes involved in PLP-induced EAE in SJL mice. Furthermore, the availability of multiple PLP-specific T cell clones will enable us to study the diversity of the T cell repertoire to PLP.