ANTIBODIES TO BRAIN INTEGRAL MEMBRANE-PROTEINS IN SYSTEMIC LUPUS-ERYTHEMATOSUS

Wheat germ lectin affinity chromatography and temperature-induced phas e separation with Triton X-114 were evaluated for the isolation of sur face neuronal antigens from rat and human brain and from human neurobl astoma cell lines IMR-6 and SK-N-SH. Both techniques yielded surface p roteins which were free of contamination by intracellular proteins but temperature-induced phase separation was technically less demanding a nd less expensive, required a shorter assay time and resulted in a sup erior quantity and quality of isolated proteins. Rat brain surface pro teins were used for characterization of antineuronal antibody reactivi ty in sera from patients with systemic lupus erythematosus (SLE). West ern blotting identified reactivity in 15 of 75 (20%) SLE sera compared to five of 95 (5%) normal controls (P 0.006). In rat brain the molecu lar weight of the individual proteins identified ranged from 59 kDa to 22 kDa. Six of these were also present in human brain and two were pr esent in neuroblastoma cell lines. Absorption studies indicated that s ome of the antigenic proteins were either restricted to brain tissue o r shared with other non-neuronal tissues. These techniques should faci litate the characterization of antineuronal antibody reactivities and lead to a clearer understanding of their role in the pathogenesis of a utoimmune neurologic disease.