The Influence of Insulin on Local Amyloidosis of the Islets of Langerhans and Insulinoma

Summary Amyloid-containing islets of Langerhans from the pancreas of 75 diabetics and one case of an amyloid-containing insulinoma were investigated. By light and electron microscopy, amyloid deposits were observed between the B cells and adjacent capillaries. The cytoplasm of B cells and extracellular amyloid display immunohistological binding of anti-insulin antibody. Correspondingly, ferritin-labeled anti-insulin antibody was found by electron microscopy on and between the amyloid fibrils. Insulin or proinsulin (or a protein closely related to insulin) thus appears to be a.component of the protein which constitutes the amyloid. The molecular weight and mode of deposition of this form of …