Prevention of experimental allergic neuritis in the lewis rat with bovine P₂ protein

Protective doses of bovine P₂ protein (5, 15 or 50 μg) in incomplete Freund's adjuvant (IFA) were administered to Lewis rats and were followed 2,4 or 10 weeks later by challenging doses of either 250 μg bovine P₂ or 2.5 mg bovine PNS myelin in complete Freund's adjuvant (CFA). Protection from experimental allergic neuritis (EAN) could be achieved with a single dose of 5 μg of P₂ in IFA. There was little difference between prophylactic 5 μg and 15 μg doses of P₂. The degree of protection depended upon the interval between protective innoculation and challenge. Protection was partial at 2 weeks and maximal at 4 weeks at which time there was complete protection against P₂-induced EAN and less complete protection from myelin-induced disease. Complete protection at 4 weeks from myelin-induced EAN was achieved with a 50 μg dose. Protection lasted for at least 10 weeks (the longest interval assessed) and was complete with respect to P₂-induced EAN. Partial protection was observed in myelin-challenged animals after 10 weeks with the level of protection greater than that observed after 2 weeks.