53 Cross-reacting antibody (AB) to alfalfa seed (AS) and deoxyribonucleic acid (DNA) in systemic lupus erythematosus (SLE)

Abstract

54 CROSS-REACTING ANTIBODY (AB) TO ALFALFA SEED (AS) AND DEOXYRIBONUCLEIC ACID (DNA) IN SYSTEMIC LUPUS ERYTHEMATOSUS (SLE). E. J. Bardana, M.D., M. R. Malinow, M.D., S. Craig, and P. McLaughlin Portland, Oregon. Dietary AS reduces plasma cholesterol in rabbits and monkeys. Ingestion by a man lowered cholesterol, but caused an SLE-like illness (Lancet 1:615, 1981). Three of 5 female monkeys fed 45% ground AS in semi-purified diet (SPD) developed an SLE-like illness as opposed to none on SPD alone. Hemolytic anemia, antinuclear AB, hypocomplementemia and anti-native DNA were noted (Am. J. Kidney Dis. 1:345, 1982). Further studies incriminated germinated AS (sprouts) and suggested L-canavanine as the responsible component (Science 216:415, 1982). To explore these observations in humans, sera from 35 patients with SLE, 28 with non-SLE rheumatic disorders and 39 normals were studied by immunodiffusion for AB to: AS extract (50 mg/ml and 100 mg/ml); sonified native DNA (1 mg/ml and 0.5 mg/ml); denatured DNA (0.5 mg/ml); and rabbit thymus extract (RTE) (20 mg/ml). Eleven of 35 SLE sera (31%) and 1 of 39 normals (3%) showed precipitins to AS extract. None were seen in patients with other rheumatic disorders (p<O.OOl). Precipitating antibody to AS extract showed lines of identity to both native DNA and RTE and was partially related to levels of serum anti-native DNA. These studies show an immunogenic ligand in AS which is present in native DNA and RTE. This shared antigen may be L-canavanine which is found in large concentrations in AS and germinated AS and which may substitute for arginine in histones.