Prolonged survival of microencapsulated neonatal porcine islets in mice treated with a combination of anti-CD154 and anti-LFA-1 monoclonal antibodies

Background. The aim of this study was to determine whether short-term administration of a combination of anti-CD154 and anti-LFA-I monoclonal antibodies can prolong the survival of microencapsulated neonatal porcine islets (NPI) in immunocompetent mice. Methods. Microencapsulated NPI were transplanted into the peritoneal cavity of streptozotocin-induced diabetic B6 mice that received a short-term treatment of a combination of anti-CD154 and anti-LFA-1 monoclonal antibodies. Blood glucose levels of each recipient were measured for more than 100 days posttransplantation or until graft rejection. Microcapsules were recovered to determine the presence of immune cells using immunoperoxidase staining. In addition, the levels of mouse anti-porcine immunoglobulin (Ig) G antibodies in the serum of each recipient were measured by flow cytometry. Results. Short-term administration of a combination of monoclonal antibodies resulted in significant prolongation of microencapsulated NPI xenograft survival. All treated mice (n=20) achieved normoglycemia within 10-35 days posttransplantation and 11/20 mice remained normoglycemic for more than 100 days posttransplantation. In contrast, only 1/20 of the untreated mice achieved normoglycemia and this mouse became diabetic at 17 days posttransplantation. Histological examination of the recovered microcapsules from long-term surviving treated mice revealed minimal cellular overgrowth containing intact viable islets, whereas several layers of immune cells surrounding the capsules containing nonviable islets were observed in untreated mice. The levels of mouse anti-porcine IgG was also reduced in treated recipients compared to untreated mice. Conclusions. These data demonstrate that short-term administration of anti-CD154 and anti-LFA-1 monoclonal antibodies can be effective in promoting long-term survival of microencapsulated NPI in immune-competent mice.