Specific removal of DNA antibodies in vivo with an extracorporeal immuno-adsorbent.

The selective removal of circulating antibody specific for DNA was affected with an immuno-absorbent consisting of DNA-cellulose incorporated into agar gel. Antisera to DNA obtained from patient with systemic lupus erythematosus was circulated in vitro through experimental and control columns by a dual channel haemodialysis pump and serial aliquots were withdrawn and assayed for antibody. A 65% reduction in DNA binding of serum was achieved at a flow rate of 210 ml/min over a 4-hr period with no release of 125I-labelled DNA from the column into the serum. For in vivo studies, 2-6-3-8 kg rabbits were actively immunized with methylated bovine serum albumin conjugated to single-stranded DNA (MBSA-ssDNA). Whole blood was pumped from the femoral artery through an immuno-adsorbent composed of ssDNA-cellulose in an agar matrix. Results showed significant reductions in ssDNA binding activity over various periods after connection of the rabbit's circulation to the immuno-adsorbent with only minimal changes in BSA binding during the same period. Little release of incorporated 125I-labelled DNA from the column as assayed in the blood and tissues of the experimental animals occurred during the procedure. The immuno-adsorbent columns showed no residual cellular debris or thrombotic material. These results suggest that this immuno-adsorbent system may be used to specifically withdraw circulating DNA antibodies in vivo. Such a system may have clinical potential for specific therapy of systemic lupus erythematosus.