High molecular weight substances with insulin immunoreactivity.

Substances which react with anti-insulin antibodies, but have a higher molecular weight than insulin are described. They have been studied by various authors in pancreatic adenomas, pancreas extracts, serum and cell-free systems. Proinsulin was the first of these products to be discovered, followed by its precursor, pre-proinsulin, and subsequently by a whole series of substances of ill-defined composition and more or less similar properties, grouped under the heading of "high molecular weight immunoreactive insulin" (HWIRI).