Breaking of tolerance to native DNA in nonautoimmune mice by immunization with natural protein/DNA complexes

A major event in the pathogenesis of systemic lupus erythematosus (SLE) is the breaking of tolerance to native DNA and the appearance of IgG anti-double-stranded (ds) DNA antibodies. The mechanisms of the losing of tolerance are not well understood. Continuous efforts have been made in the past to induce anti-native DNA IgG autoantibodies in non-autoimmune animals but the relevance of the approaches used to what happens in spontaneous disease is unclear. We succeeded in breaking tolerance to native DNA in nonautoimmune-prone BALB/c mice by immunization with natural DNA/protein complexes. These complexes included nucleosomes, crude commercial histone and nucleohistone preparations. The anti-dsDNA IgG response lasted for more than an year. IgG deposition in the kidneys of the animals was repeatedly shown. As DNA-specific B cells behave in many ways as non-autoreactive B cells, we suggest that the activity of the self-reactive B lymphocytes could be selectively inhibited in a way that mimics a physiological mechanism controlling the magnitude and duration of the IgG antibody response to foreign antigens.