Islet transplantation--synergism between antilymphocyte and antimacrophage agents.

The aim of this study was to assess the efficacy of a combination of antimacrophage (silica) and antilymphocyte (antilymphocyte serum and cyclosporin A) agents in suppressing islet allograft rejection across a major histoincompatibility in rats. Isolated islets were obtained using the collagenase digestion and Ficoll gradient separation technique and transplanted intraportally into streptozotocin-induced diabetic recipients. Of the three agents used alone only cyclosporin A prolonged graft survival (median of 10 days), a combination of antilymphocyte serum (ALS) and cyclosporin A prolonged graft survival to a median of 23 days, and a combination of ALS, cyclosporin A, and silica prolonged survival to a median of 74 days. The role of macrophages in rejection is still undefined but the synergism between antimacrophage and antilymphocyte agents provides further evidence of their importance in islet allograft rejection.