Antigenic determinants on bovine encephalitogenic protein. Localization of regions that induce transformation of lymph node cells from immunized rabbits

Evolutionary divergence in the structure of myelin basic protein: comparison of chondrichthye basic proteins with those from higher vertebrates

A basic protein has been purified from the CNS myelin of the gummy shark (Mustelus antarticus). Electroblotting was used to examine the capacity of rabbit antisera raised against this electrophoretically pure protein to recognize myelin basic protein from higher vertebrates. The antisera bound to two shark proteins including the original polypeptide antigen and to chicken, bovine, and human myelin basic proteins. Thus, the shark protein appeared to possess antigenic determinants that have been retained through evolutionary divergence of these proteins. Whereas bovine basic protein caused experimental allergic encephalomyelitis in guinea pigs, animals that received injections of the shark protein showed neither clinical nor histological signs of this disease. However, tests for delayed-type hypersensitivity and for Arthus reaction following injection with the shark protein revealed a T-cell-mediated response to this antigen and substantial cross-reactivity with higher vertebrate basic proteins. Analysis of the amino acid composition of the shark protein, and comparison of its tryptic peptide map with that of the bovine protein, revealed substantial changes in the amino acid sequence. Although the shark protein has some antigenic determinants in common with the proteins from higher vertebrates, it appears that much of the structure differs.

Cell-mediated immune response to guinea pig and bovine basic proteins of myelin in Lewis and PVG rats and their hybrids

The in vitro cell-mediated immune response of rat lymph node cells (LNC) to guinea pig and bovine encephalitogenic protein (EP) has been studied with a LNC transformation test. LNC were obtained from either Lewis, PVG, or F1 (Lewis x PVG) rats 28 days after challenge with guinea pig or bovine EP in Freund's complete adjuvant (FCA) of different mycobacterium content. No differences between the strains or their hybrids in LNC response could be shown if stimulated with sensitizing EP, despite the great differences in capacity for disease development in those animals. Nor did a fivefold lowering of the amount of mycobacterium content in FCA, when guinea pig EP was used at challenge, lessen the in vitro response, although this reduces the disease development. Sensitization with guinea pig EP causes an in vitro cross-reactivity to bovine EP and the reciprocal cross-reactivity probably also exists. In rabbits, this cross-reactivity in both directions was clear-cut. LNC from Lewis rats challenged with guinea pig EP in FAC, with the higher amount of mycobacterium, showed in vitro responses to tested peptides of this EP; the amino acid sequences of these were: 1-42, 43-88, 89-169, and HNB-89-169 (89-169 blocked at the tryptophan-residue by hydroxynitrobenzylation).

Leukocyte migration in agarose, a study on multiple sclerosis

The effect of low concentrations of bovine encephalitogenic protein on the migration of human peripheral leukocytes in agarose was studied. A concentration of 0.3 mug/ml of the protein stimulated the migration of cells from many donors, including some healthy subjects. An indirect technique suggested that the migration enhancement is due to the production of soluble factor, possibly corresponding to the leukocyte migration enhancement factor described by others. The frequency of subjects whose cells could be stimulated and the recorded degree of stimulation tended to be higher in a group of patients with multiple sclerosis than in a group of healthy subjects. When the effect of some of the main peptide fragments of the protein was studied on cells that were stimulated by the intact protein, one or more of these peptides sometimes induced the opposite effect: a migration inhibition. There is, apparently, a complex balance between enhancing and inhibiting factors acting on leukocyte migration in vitro; and the character of the antigen seems to be one important factor.