Characteristics of a soluble nuclear antigen precipitating with sera of patients with systemic lupus erythematosus

Abstract

Precipitating antibodies which reacted with soluble extracts of different human tissues or nuclei including nuclei from calf thymus were found in sera of patients with systemic lupus erythematosus. The antigen was different from DNA and histone, but was associated with protein fractions and insensitive to deoxyribonuclease, ribonuclease and trypsin, but sensitive to periodate treatment. The reactivity was detected by Ouchterlony double-immunodiffusion and by immunoelectrophoresis techniques. The reactive serum factor was shown to migrate in the gamma globulin fraction. The antigen was provisionally termed ‘Sm’ and the reactivity was described to be found in approximately 75% of SLE patients but only very few patients with other disorders.