Frank C.-H. Chou

THE MAJOR SITE OF GUINEA‐PIG MYELIN BASIC PROTEIN ENCEPHALITOGENIC IN LEWIS RATS12

In the Lewis rat, fragment 43–88 of the highly encephalitogenic guinea‐pig basic protein has been previously shown to retain the full activity of the parent protein. In the present studies this fragment was subjected to controlled chymotryptic digestion so that cleavage occurred only at tyrosine 67, generating two peptides, residues 43‐67 and residues 68‐88. When compared on an equimolar basis peptide 68‐88 had the same encephalitogenic activity as the intact fragment and induced the same degree of immunologically specific cell response as measured by the in vitro lymphocyte stimulation test. Peptide 68‐88 was further fragmented by selective tryptic cleavage at arginine 78 after blocking lysine 73 with citraconic anhydride. The two peptides, residues 68‐78 and residues 79‐88, were not encephalitogenic, indicating that residues adjacent to the point of cleavage contribute to the active site.

Encephalitogenic protein: structure.

Amino acid sequences of encephalitogenic proteins from bovine cord and rabbit brain are reported. The bovine protein contains 45 residues. The rabbit protein is identical except for two isopolar substitutions, a dipeptide and amino acid deletion. Analysis of this protein and a 140-residue myelin basic protein indicates that the smaller protein is a portion of the larger encephalitogen. The larger myelin protein contains at least two encephalitogenic sites.

Identity of myelin basic protein from multiple sclerosis and human control brains: discovery of a genetic variant.

Abstract— Myelin basic protein was isolated from the brains of 7 multiple sclerosis and 5 control patients. When acid extracts of the delipidated brains were chromatographed on carboxymethylcellulose at alkaline pH the elution profiles were the same for the two groups of patients. Component I, the most basic species of the protein, from 2 multiple sclerosis and one control brains was fragmented by limited pepsin digestion. Tryptic peptide maps were prepared from the three major products, fragment 1–38, 39–89 plus 45–89 and 90–170. The amino acid compositions of corresponding peptides were identical except for a 50:50 substitution of serine for glycine in tryptic peptide 44–49 from one (N.L.) of the 2 patients with multiple sclerosis. Peptide 44–49. isolated from intact component 1 from the other 6 multiple sclerosis and 5 control brains, did not show this substitution. In both multiple sclerosis and control basic proteins phosphorus was present only in fragment 90–170 of component 3 in the amount of 0.22 mol of phosphorus/mol of protein. These data suggest that there is no difference in either the amino acid sequence or in the modification of basic protein from control and multiple sclerosis patients. The amino acid substitution in patient N.L. represents the first example of a mutation in basic protein.

Antigenic regions for the humoral response to myelin basic protein.

Abstract The major encephalitogenic sites in myelin basic protein (BP) † differ among animals tested. In order to define further the antigenic features of BP and to explore the possibility that antigenic sites recognized for antibody production might also differ among species, the contribution of regions of BP to the total antigenic activity of the molecule was examined in guinea pigs and rabbits. Twenty-one guinea pigs, 13 Hartley and 8 strain 13, were given a series of immunizations with bovine or guinea pig BP administered with large amounts of Mycobacterium tuberculosis . Eleven New Zealand white rabbits were immunized with bovine or guniea pig BP alone or conjugated to albumin. Antisera were tested by double antibody radioimmunoassay for reactivity with BP and BP peptides. Antisera from all guinea pigs reacted with BP and peptide 89–169 but had little or no reactivity with peptides 1–36 and 43–88. All rabbit antisera reacted well with BP, peptide 89–169 and peptide 1–36. Reactivity of rabbit antisera with peptide 43–88 was variable. It was present, usually in low titers, in 5 animals. The pattern of reactivity of rabbit antisera to BP and BP peptides was established early during the course of immunization. Rabbit antisera reactive with BP peptide 43–88 showed limited, if any, activity toward peptide 79–88, thus providing additional information about the inaccessibility or conformational dependence of the antigenic site in the molecular region of residues 79–88.

Devic's syndrome Antibody to glial fibrillary acidic protein in cerebrospinal fluid

The cerebrospinal fluid of a patient with Devics syndrome contained antiglial fibrillary acidic protein antibody. The serum level of antibody was less than that in cerebrospinal fluid, and the antibody was probably synthesized within the central nervous system. Similar antibody was not found in another patient with Devics syndrome or in patients with multiple sclerosis. The role of the antibody in the patients illness is uncertain, but is one of the few instances in which antibody against a specific brain antigen has been described in human demyelinating disease.

Search for a multiple sclerosis‐specific brain antigen

Specific reactivity of multiple sclerosis (MS) cerebrospinal fluid (CSF) IgG against central nervous system (CNS) tissue has been sought. Brain proteins were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), reacted with CSF followed by 125I-Staph protein A, and developed for autoradiography. Pooled CSF from MS patients, CSF from individual MS patients, and pooled CSF from patients with other neurologic diseases and from normal patients, were used. Proteins were extracted from the white matter of MS and normal brains and from MS plaque and peri-plaque tissue. No reactivity specific for MS was observed.