title: A serum factor cross-reactive with antibodies to a determinant of rabbit encephalitogenic sequence 65-74 of myelin basic protein.
abstract: A serum factor, cross-reactive with antibodies to a defined determinant of myelin basic protein (residues 66-71), has been found in the sera of nine mammalian species where it may function as a specific neuroautotolerogen. In equilibrium competitive inhibition radioimmunoassays the factor appears to be completely competitive with synthetic peptide S24 (TTHYGSLPQKG) at high affinity and is therefore termed MBP-SF-24 (myelin basic protein serum factor of the S24 type). The bulk of the activity can be recovered by ammonium sulfate fractionation at 61.1% saturated ammonium sulfate (SAS), pH 7, (fraction E) after removal by precipitation at pH 7 of the 37.5, 42.6, 47.5, and 51.4% SAS fractions (fractions A-D), including the immunoglobulins, and before removal by precipitation at pH 5 of the albumin fraction (fraction F). The factor, by its retention on XM300 during ultrafiltration of fraction E, can be purified 20-fold from serum proteins without much loss through a combination of SAS fractionation and ultrafiltration. The yield of MBP-SF-S24 in fraction E may range from a low 26 pmol S24 equivalents from 10 ml in sheep serum to a high 1.7 nmoles from 10 ml rat serum. The serum factor is reactive at high affinity with each of two populations of S24-reactive antibodies in one rabbit reagent antiserum and with one of two populations of S24-reactive antibodies in another. It appears to express a determinant involving residues THYGSL (66-71) of myelin basic protein with the same conformation as found in intact S24.
authors.forename: E D
authors.initials: ED
authors.lastname: Day
authors.forename: G A
authors.initials: GA
authors.lastname: Hashim
authors.forename: K J
authors.initials: KJ
authors.lastname: Lazarus
authors.forename: P Y
authors.initials: PY
authors.lastname: Paterson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D001798:Blood Proteins / Q000032:analysis* / Q000276:immunology; D002417:Cattle; D003429:Cross Reactions; D004285:Dogs; D000939:Epitopes; D006168:Guinea Pigs; D051379:Mice; D004676:Myelin Basic Protein / Q000032:analysis / Q000276:immunology*; D011817:Rabbits; D051381:Rats; D012756:Sheep; D013045:Species Specificity; D013552:Swine; D014462:Ultrafiltration
chemical_list: D000906:Antibodies; D001798:Blood Proteins; D000939:Epitopes; D004676:Myelin Basic Protein; C032632:myelin basic protein-serum factors