Utilization of anti-acinar cell monoclonal antibodies in the purification of rat and canine islets.

We have developed two immunological methods of islet purification using anti-acinar cell monoclonal antibodies (McAb). Pancreatic digestion with collagenase followed by depletion of acinar cells with McAb and complement or magnetic immunomicrospheres (MIMS) yields large numbers of intact islets. We compared the islets thus obtained with either handpicked (HP) islets, or islets separated on density gradients alone, for yield, purity, in vitro in sulin secretory capacities, and in vivo functional viability. Exposure of canine acinar tissue to the cytotoxic McAb resulted in a seven-fold enrichment in islet concentration, with preparations of 65% to 87% purity. Islet yield, however, was impaired by the procedure of McAb treatment, reducing the average yield from the control digestate of 40,000 to 60,000 islets/pancreas by 40% to 45%. Using the MIMS method in the rat model, the islet yield was 73% that obtained by the HP method (378 +/- 8 vs 519 +/- 31 per pancreas). The purity of the MIMS isolated islets was 84 +/- 1.9%, ranging from 75% to 95%. Analysis of the complement and MIMS treatments by in vitro static glucose tests and the capacity to restore normoglycemia after isografting in streptozotocin-induced diabetic rats indicates that the functional integrity of the islets was not affected by the purification process.