The immune response to myelin proteolipid protein in the Lewis rat: identification of the immunodominant B cell epitope.

The polyclonal antibody response of the Lewis rat to bovine myelin proteolipid protein (PLP) has been investigated following immunisation with either the purified protein or bovine central nervous system myelin. In both situations, the carboxyl-terminal sequence of PLP was identified as the immunodominant domain of this protein and epitope mapping demonstrated that the carboxyl-terminal amino acid, phenylalanine276, was a critical requirement for antibody recognition of this epitope. This single epitope accounted for approximately 78% and 56% of the antibody response to PLP in rats immunised with PLP or bovine myelin, respectively. Polyclonal rat antibodies specific for this carboxyl terminal epitope of PLP were also obtained following immunisation with a synthetic 20 amino acid oligopeptide analogue of the carboxyl-terminal sequence of PLP. Western blotting demonstrated this antibody response was specific for the PLP and DM-20 components of mammalian central nervous system myelin. In contrast, no major PLP epitopes were detected within the PLP amino acid sequences 35-58 and 91-150, the other major hydrophilic domains of this protein.