High Prevalence of Autoantibodies Against Carbonic Anhydrase II and Lactoferrin in Type 1 Diabetes: Concept of Autoimmune Exocrinopathy and Endocrinopathy of the Pancreas

INTRODUCTION: Dysfunction of the exocrine as well as the endocrine pancreas has been reported in type 1 diabetes. Lymphocytic infiltration of the exocrine pancreas is observed in approximately half of Japanese type 1 diabetic patients. AIMS: To investigate the involvement of autoimmunity against the exocrine pancreas in type 1 diabetes. METHODOLOGY: We examined autoantibodies against human carbonic anhydrase II (ACA) and lactoferrin (ALF), antigens in the pancreatic duct cells and the pancreatic acinus, respectively, in 43 type 1 diabetic patients and 20 type 2 diabetic patients using the enzyme-linked immunosorbent assay method. RESULTS: Of 43 type 1 diabetic patients, ACA was detected in 28 patients (65%) and ALF was detected in 29 patients (67%). One or both of the antibodies were detected in 33 type 1 diabetic patients (77%). In contrast, neither ACA nor ALF were detected in type 2 diabetic patients. CONCLUSIONS: The high prevalence of both ACA and ALF strongly suggests the involvement of autoimmunity against the exocrine pancreas as well as the endocrine pancreas in some type 1 diabetic patients. We propose that these conditions be referred to as autoimmune exocrinopathy and endocrinopathy of the pancreas.