Characterization of immune complexes of idiotypic catalytic and anti-idiotypic inhibitory antibodies in plasma of type 1 diabetic subjects.

An increase in proteolytic activity is an early common feature of diabetes, and is associated with the development of vascular complications. We performed an extensive proteomic investigation on plasma of type 1 diabetic subjects to discover why some of them apparently lacked any measurable proteolytic activity. Activity was found enclosed in immune complexes in which Fab/(Fab)(2) displayed a serine-like catalytic activity.