Preparation and In Vitro Evaluation of a New Extracorporeal Dialyzer with Immobilized Insulin

A specific extracorporeal immunoadsorbent system has been developed that has potential application for the treatment of complications related to the presence of plasma insulin antibodies, namely severe insulin resistance and autoimmune hypoglycemia. The immunoadsorbent system described here makes use of a commercially available cellulose‐based, hollow‐fiber hemodialyzer. Optimal conditions for the coupling of insulin to cellulose matrices were found to involve activation with 1,4‐butanediol diglycidyl ether and reaction with insulin at pH 7.4. The insulin‐dialyzer prepared under these conditions contained 35.5 mg to 37.9 mg of insulin which correspond to a theoretical binding capacity of 887.5 to 947.5 units of insulin. Recirculation of human plasma with high insulin antibody titers through the insulin‐dialyzer resulted in the clearance of 82–99% and 50–83% of high affinity and total insulin antibodies, respectively. The clearance of insulin antibodies approached a steady state after 15 minutes of recirculation at a flow rate of 50 ml/min. Regeneration of used insulin‐dialyzers was accomplished by treatment with 0.02 M citrate buffer pH 3.2, which restored their ability to clear 90% and 40% of high affinity and total insulin antibodies, respectively. The principle of the insulin‐dialyzer may find application in other disease states where removal of specific antibodies or other high molecular weight species may be of therapeutic value.