Complement-fixing islet-cell antibodies in type-I diabetes: possible monitors of active beta-cell damage.

Evidence is presented for the existence of a separate species of islet-cell antibodies which fix complement. Investigations in type I diabetics, non-diabetic polyendocrine patients, and unaffected first-degree relatives of type I diabetic probands show that the complement-fixing islet-cell antibodies are more closely related to the onset of clinical disease than the conventional islet-cell antibody, and they tend to disappear more rapidly. The complement-fixing antibodies may reflect damage of pancreatic beta cells more selectively and may be preferable to the conventional antibody as a serological marker for studying the natural history of type I diabetes.