Plasma C-peptide and serum insulin antibodies in diabetic patients receiving pancreatic transplants

Plasma C-peptideand serum insulin antibody levels were determined in 5 diabetic patients undergoing vascularized pancreatic transplantation. The grafts functioned well at first and exogenous insulin could be withdrawn, but one to 7 weeks later the grafts were rejected. After the transplantation there was an increase in the fasting plasma C-peptidelevel, and B-cell stimulation with glucose or glucagon evoked a C-peptideresponse. Healing of ischaemic damage was reflected in an increase in the C-peptidelevel. During graft rejection the C-peptide level fell. Measurementof plasma C-peptidelevels provides a direct index of the B-cell function of the pancreatic graft. After transplantation the insulin antibody level fellexponentially, with an apparent half life of 10–11 days, whereas the level of total IgG was variable. The results indicate that formation of insulin antibodies ceases immediately on removal of the immunogenic stimulus, that is, on withdrawal of xenogeneicinsulin.