Purification of Fully Active Human Encephalitogenic Basic Protein on Sulfoethyl-Sephadex

Abstract

Human encephalitogenic basic protein (HEP) was obtained in high yield after chromatography on sulfoethyl-Sephadex C-50 (SE-Sephadex). The protein was shown to be homogeneous and was identical in physical properties with samples of human encephalitogenic protein obtained by other methods. It was also shown to induce typical clinical and histological experimental allergic encephalomyelitis (E.A.E.) in adult guinea pigs injected with 50 μg HEP in Freund's complete adjuvant (FCA). Gel-filtration radioimmunoassay was used to study immunogenicity, antigenicity, and antigenic cross-reactivity of HEP; seven of 11 guinea pigs injected with HEP in FCA had detectable serum antibody to 125I-HEP, indicating that the SE-Sephadex preparation was fully immunogenic and antigenic; HEP and another preparation of human encephalitogenic basic protein prepared by a different method were equally capable of inhibiting the binding between 125I-HEP and anti-HEP serum indicating that the two samples tested were antigenically identical. We believe that the new technique represents a significant technological advance because it provides a most effective and rapid method for the isolation of fully active encephalitogenic basic protein.