Autoantibodies to neuroblastoma cell surface antigens in neuropsychiatric lupus

A human neuroblastoma cell line, LA-N-1 was used as a target cell in a I131 radiolabeled staphylococcal protein-A (I131-SpA) binding assay, to characterize the pattern of antineuronal activity of human sera in fifty-four cases of systemic lupus erythematosus (SLE) including twenty-six patients with neuropsychiatric manifestations of SLE (LE-CNS), out of which ten were pediatric patients aged eleven to eighteen years, thirty-six normal donors and sixteen rheumatoid arthritis patients. The IgG binding activity of normal control sera with LA-N-1 neuroblastoma cells was determined to be 998 +/- 490 cpm I131-SpA, per 5 micrograms LA-N-1 protein (mean +/- SD), 2936 +/- 2607 cpm I131-SpA per 5 micrograms LA-N-1 protein for rheumatoid arthritis patients, 5109 +/- 3304 cpm I131-SpA per 5 micrograms LA-N-1 protein for SLE patients. The binding activity of for LE-CNS patients sera was: 10 565 +/- 2993 and 15 346 +/- 2993 cpm I131-SpA per 5 micrograms LA-N-1 protein, for the pediatric and adult group of patients respectively. Absorption assays disclosed that the antineuronal IgG autoantibody detected in the LE-CNS group of patients is cross reacting with human adult brain, while the anti-neuronal activity of rheumatoid arthritis and SLE patients could be removed by sequential absorption with homogenates of human lung, liver, and kidney, fetal calf serum, human muscle and human lymphocytes. We conclude that detection of autoantibodies binding to LA-N-1 human neuroblastoma cells may be helpful in the diagnostic workup of pediatric and adult LE-CNS patients.