In vitro anti-DNA antibody synthesis by peripheral blood lymphocytes from systemic lupus erythematosus (SLE) patients after native DNA (nDNA) stimulation was studied by the Farr assay after digestion with deoxyribonuclease I. Active SLE lymphocytes synthetized IgG and anti-DNA antibody with nDNA stimulation but inactive SLE and normal lymphocytes did not. Binding of 14C-labeled Ig and [3H]DNA showed that DNA-binding Ig was actively secreted by SLE lymphocytes. SLE antilymphocyte antibody (ALA)-sensitive T cells (SLE+ T cells) and unreactive T cells (SLE- T cells) were separated by anti-human Ig antibody-coated dishes to determine their effect on antibody synthesis. Inactive SLE B cells synthetized both IgG and anti-DNA antibody after nDNA stimulation with autologous SLE- T cells but stimulation with SLE+ T cells did not result in synthesis of either. Normal B cells did not synthetize IgG even with autologous SLE- T cells. These results indicate that active and inactive SLE patients have autoreactive lymphocytes against nDNA which synthetize anti-DNA antibody and are regulated by ALA-sensitive T cells (possibly deficient in active SLE).
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