Effect of islet-activating protein (IAP) upon insulin secretion from human pancreatic islets.

A new protein termed islet-activating protein (IAP) has recently been extracted from the culture medium of Bordetella pertussis, and shown to enhance insulin secretion in vivo in rats or in vitro in isolated pancreatic islets due to activation of native calcium ionophores. However, it has not been clarified whether or not IAP enhances the secretion of insulin in human pancreatic islets. In order to examine the effect of IAP on human pancreatic islets, pancreatic tissues were obtained from seven patients who had appeared normal in a glucose tolerance test prior to pancreatectomy. Insulin secretion was significantly increased in IAP treated pancreatic islets by the glucose and the arginine stimuli. It is concluded that IAP enhances the insulin secretion in response to insulin secretagogues in human pancreatic islets, suggesting the possible clinical application of IAP to diabetic patients.