Amylase {alpha}-2A Autoantibodies: Novel Marker of Autoimmune Pancreatitis and Fulminant Type 1 Diabetes Mellitus.

Objective: The pathogenesis of autoimmune pancreatitis (AIP) and fulminant type 1 diabetes (FT1DM) remains unclear, although it is known that immune-mediated processes severely compromise the endocrine and exocrine functions in both diseases. Methods: We have screened a lambdaTriplEx2 human pancreas cDNA library with serum from a patient with AIP and obtained positive clones. Sequence analysis revealed that seven out of 10 clones were identical to human amylase alpha-2A. Using a recombinant C-terminal amylase alpha-2A protein, we developed an enzyme-linked immunosorbent assay system to detect autoantibodies against human amylase alpha-2A. Results: All 15 serum samples from patients with AIP recognized the recombinant protein, while sera from 25 patients with chronic alcoholic pancreatitis and sera from 25 patients with a pancreas tumor did not. Interestingly, 88% (15/17) of patients with FT1DM were positive for an autoantibody against amylase alpha-2A. These antibodies were detected in 21% of patients with acute-onset type 1 diabetes (AT1DM, 9/42) and 6% of type 2 diabetic patients (4/67). Conclusions: These results suggest that an autoantibody against amylase alpha-2A is a novel diagnostic marker for both AIP and FT1DM, and that clinically and immunologically, AIP and FT1DM are closely related.

Endo T, Takizawa S, Tanaka S, Takahashi M, Fujii H, Kamisawa T, Kobayashi T.
Diabetes. 2008 Nov 10