Autoantibodies in systemic lupus erythematosus.

Lupus anti-DNA may have higher homology with germline than those from normal subjects. However, in NZB/NZW mice, bacterial DNA is more antigenic than mammal DNA, which could indicate an antigen-driven origin. High-affinity antibodies to double-stranded DNA cross-react with small nuclear ribonucleoprotein and ribosomal P proteins. These cross-reactive anti-DNA may penetrate live cells. Antibodies to ribosomal P proteins are associated with neuropsychiatric, renal, and hepatic lupus involvement. IgG antibodies to (H2A-H2B)-DNA complexes antedate procainamide-induced lupus. Autoantibodies to some La/Ro peptides in a mother indicates that her children may develop neonatal lupus and determine who will have congenital heart block. Perinuclear antineutrophil cytoplasmic antibodies are present in 25% of systemic lupus erythematosus patients without correlation with anti-DNA or disease activity. Different antiphospholipid antibodies require different protein cofactors for reactivity. Those to anionic phospholipids require beta 2-glycoprotein I, whereas anti-phosphatidylethanolamine antibodies require kininogen or its binding protein. Antibodies to phospholipid-free beta 2-glycoprotein I are associated more strongly with clinical antiphospholipid syndrome than are antiphospholipid antibodies.