Serum IgM repertoire reactions to MBP/CFA immunization reflect the individual status of EAE susceptibility

Lewis rats develop experimental allergic encephalomyelitis (EAE) in respons e to immunization with myelin basic protein (MBP) in CFA, while Fischer rat s are usually resistant. These strains, while comparably producing anti-MBP antibodies,also differ in their repertoire reactions to immunization, as m easured by patterns of serum IgM reactivity with various autologous protein s. We have now scored IgM repertoire reactions to MBP/CFA immunization afte r treatments that alter EAE susceptibility in either strain. The results sh ow that abrogation of EAE susceptibility in Lewis rats by a previous experi ence of T cell-induced passive EAE provoked a novel set of IgM reactivities that otherwise characterized the Fischer's repertoire reaction. Conversely , these reactivities were delayed in the response of Fischer rats that had been rendered EAE-susceptible by cyclophosphamide. Another IgM reactivity w ith a significant association to individual EAE severity in Lewis rats beha ved reciprocally. Together with previous results, these observations sugges t that putative regulatory mechanisms concordantly affect EAE resistance an d IgM repertoire reactions, operating naturally in Fischer rats and abrogat able by cyclophosphamide treatment, whereas naturally suppressed, but resto rable in Lewis rats. Other treatments altering EAE susceptibility, however, did not share these characteristics and may thus be mediated by other (C) 2000 Academic Press.