ISSN:
1432-0428
Keywords:
Islet amyloid polypeptide
;
Type 2 (non-insulin-dependent) diabetes
;
insulin secretion
;
immunohistochemistry
;
islet B cell
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary A novel peptide, islet amyloid polypeptide (IAPP), with structural resemblance to calcitonin gene-related peptide has recently been purified from amyloid deposits in an insulinoma and from islets of Langerhans. By immunohistochemical methods, using antisera to a synthetic undecapeptide of IAPP and to insulin, we show that freshly fixed islet B cells in man, guinea pig, rat, mouse and hamster exhibit strong IAPP-immunoreactivity while A cells are unreactive. In human autopsy material, all of 11 non-diabetic individuals had IAPP immunoreactivity of the islets. In comparison 8 of the 13 patients with Type 2 (non-insulin-dependent) diabetes had no IAPP immunoreactive cells. The proportion of islet cells having IAPP immunoreactivity exceeded 10% in only 1 of the 5 remaining diabetic patients while in all 13 patients substantially more than 10% of the islet cells contained immunoreactive insulin. IAPP-positive amyloid deposits were found in 20–99% of the islets in 12 of the Type 2 diabetic patients while 6 of 11 non-diabetic subjects had amyloid in 3–11% of their islets. In islets with IAPP-immunoreactive amyloid, very few IAPP-cells were seen despite a strong reaction of the B cells with antiserum to insulin. This study shows that IAPP is a normal islet B cell component and that IAPP immunoreactivity in B cells is diminished in Type 2 diabetes while IAPP is deposited as amyloid fibrils in the islets of Langerhans. Although the function of IAPP is unknown, its occurrence in the islet B cells and its structural relation to calcitonin gene-related peptide makes a hormonal nature probable. The present study indicates an altered expression or metabolic fate of IAPP in Type 2 diabetes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00274799
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