Role of Amylase-α2A Autoantibodies in the Diagnosis of Autoimmune Pancreatitis.
OBJECTIVE
Several serological markers have been reported in autoimmune pancreatitis (AIP) patients. However, only serum IgG4 (sIgG4) is available in clinical practice for AIP diagnosis. Antiamylase α antibodies (AMY-α Abs) have been proposed to diagnose AIP. This study evaluates the utility of AMY-α Abs and sIgG4 for AIP diagnosis.


METHODS
Twenty-five AIP patients, 84 disease control groups (31 chronic pancreatitis, 30 acute pancreatitis, 23 pancreatic adenocarcinoma), and 59 healthy donors were prospectively studied. The AMY-α Abs were determined by homemade enzyme-linked immunosorbent assay and sIgG4 by nephelometry.


RESULTS
Increased sIgG4 were detected to be present in 52% of AIP, 5% in control groups, and 0% in healthy donors, and AMY-α Abs, respectively, in 76%, 36%, and 2%. sIgG4 was elevated in 92% of the 13 patients with type 1 AIP, but in none of 3 with type 2 and of 8 with not otherwise specified AIP. The AMY-α Abs were present in 79%, 67%, and 75% of type 1, type 2, and not otherwise specified AIP, respectively. Sensitivity and specificity of AMY-α Abs were 76% and 78%, and of sIgG4 50% and 94%. By combining the 2 serological markers, sensitivity was 41%, and specificity was 99%.


CONCLUSIONS
The AMY-α Abs may help to diagnosis of AIP and to differentiate AIP subtypes.
From the *Immunology Service, Hospital Universitario Marqués de Valdecilla-IFIMAV, Santander, Spain; and †Department of Medicine, Pancreas Center, University of Verona, Verona, Italy.
María
M
Sánchez Castañón
Valeria
V
Zuliani
Antonio
A
Amodio
Pietro
P
Campagnola
Anna
A
Granato
Armando
A
Gabbrielli
Luigi
L
Benini
Marcos
M
López Hoyos
Luca
L
Frulloni
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D001323:Autoantibodies / Q000097:blood*; D001327:Autoimmune Diseases / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D015415:Biomarkers / Q000097:blood*; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D008297:Male; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D055292:Pancreatic alpha-Amylases / Q000276:immunology*; D010195:Pancreatitis / Q000097:blood* / Q000175:diagnosis / Q000276:immunology; D050500:Pancreatitis, Chronic / Q000097:blood / Q000175:diagnosis / Q000276:immunology; D012680:Sensitivity and Specificity; D055815:Young Adult
D001323:Autoantibodies; D015415:Biomarkers; D007074:Immunoglobulin G; C513534:AMY2A protein, human; D055292:Pancreatic alpha-Amylases