The 21-residue peptide MOG 35-55 contains an antigenic epitope responsible for the activation of CD8 encephalitogenic T cells in mice. Two truncated peptides, MOG 40-54 and MOG 44-54 were shown to bind the recombinant H-2Db protein. This complex then binds MOG specific CD8 T cells. While MOG 40-54 retained the full capability of inducing paralytic disease, MOG 44-54 only partialy causes clinical paralysis and central nervous system inflamation.