High antigenicity of intraperitoneal insulin infusion via implantable devices: Preliminary rat studies

Intraperitoneal insulin infusion of Genapol stabilized insulin Via implanta ble devices significantly improves diabetes control and hypoglycemia freque ncy in type 1 diabetes while it increases insulin antibody levels. Causes f or this particular antigenicity remain unknown. The role of insulin modific ations occurring in the reservoir on the antigenicity observed was assessed by comparing the antigenicities of the insulin coming from the vial or fro m the pump reservoir, Rats were injected intraperitoneally with insulin sam pled either from a vial (group 1) or from a pump reservoir during a refill of a clinical trial (group 2). Two control groups, one without insulin, the second one receiving a mixture of silicone and insulin were also studied, Human insulin antibody levels were assessed by RIA 10 days after 4 weekly i mmunizations. AIA levels were higher in group 1 compared to group 2 (P = 0. 003 for the first experiment, P = 0.04 in the second experiment). The incre ased antigenicity of the insulin sampled from the implanted pump might be d ue to the insulin modifications occurring during the storage in the device. Insulin aggregates could be involved in this antigenicity since they are k nown to be antigenic and their concentration was shown to be related to the amplitude of the antigenic response.