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

The selective removal of circulating antibody specific for DNA was effected with an immunoabsorbent consisting of DNA cellulose incorporated into agar gel. Antisera to DNA obtained from a 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in vitro through experimental and control columns by a dual channel haemodialysis pump and serial aliquots were withdrawn and assayed for antibody.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.