Antibodies to nucleic acids in human and murine lupus

Antibodies to nucleic acid are present in the sera of patients with systemic lupus erythematosus and in the sera of NZB/NZW F1 mice, an animal model for human systemic lupus erythematosus. Sera can be fractionated by sucrose-density gradient ultra-centrifugation and individual fractions assayed for binding of radioactive DNA, RNA or DNA: RNA hydridsive DNA, RNA or DNA: RNA hybrids. Immunoglobulin determinations can also be performed on these fractions. Antinucleic acid antibody activity can be recovered both in the 19S IgM and 7S IgG fractions. Individual variations from patient to patient suggest that more detailed analysis of immunoglobulin classes may provide insights into the pathogenesis of lupus.