Species cross-reactivities of antisera reacting with myelin basic peptide 43-88. Applications for the detection of peptide in rabbit plasma.

Previous investigations have demonstrated that the detection and measurement of peptides of myelin basic protein (BP) by immunochemical procedures are heavily dependent on the conformation of BP peptides and the specificities of antisera to these peptides. In the present study a double antibody-radioimmunoassay was used to assess the species specificity of antisera from 4 rabbits and 2 sheep against myelin basic protein (BP) peptide 43-88. Although some antisera showed broad reactivity, others were selective for species of BP used in the immunogen. By optimizing the reaction of one of the sheep anti-human peptide 43-88 for detection of rabbit BP peptide 43-88, it was possible to detect immunoreactive BP peptide 43-88 in the plasma of rabbits previously injected with bovine BP peptide 43-88 and complete Freund's adjuvant (CFA). Peptide could be detected in plasma for 1-2 days immediately after subcutaneous injection and again between days 20 and 50. Plasma antibody to rabbit BP peptide 43-88 also appeared 15-20 days after immunization and persisted often in an oscillatory pattern reciprocal for the peptide level. Neither peptide nor antibody was detected in the plasma of normal rabbits or of rabbits injected with bovine spinal cord homogenate-CFA, bovine renal homogenate-CFA or CFA alone. There was no relationship of the level of immunoreactive BP peptide 43-88, antibody to this peptide or their patterns to clinical or neuropathological changes in the animals. Quantitation and analysis of BP peptides in body fluids of animals with diseases affecting central nervous system myelin may provide information relevant to human demyelinating diseases.