title: Detection of autoantibodies to amylase by ELISA: comparison of detection of macroamylase and free autoantibody.
abstract: New ELISAs for detecting macroamylase or free autoantibodies to amylase were tested with 48 samples that had been characterized by gel chromatography and electrophoresis. The macroamylase ELISA, with anti-IgG or anti-IgA for detection, detected macroamylase in 28 of 33 samples known to contain macroamylase (85% sensitivity), whereas the ELISA for free autoantibody to amylase was positive for only 11 samples. Specificities of both ELISAs were 93%. Among 28 true positives detected with the macroamylase ELISA, 22 contained IgA, 3 contained IgG, and 3 contained both immunoglobulins. Detection of IgM added no true positives. ELISA responses (y) were proportional to log [macroamylase concentration by chromatography (x)] from 0 to 1200 U/L: y = 5.15 x + 1.66; r = 0.72; Sy x = 1.65. As new tools for detecting macroenzymes consisting of enzyme-autoantibody complexes, the ELISAs show that some autoantibodies are detected more sensitively as antibody-antigen complexes than as free antibody.
authors.affiliation: Department of Pathology, University of Alabama at Birmingham 35233-7331.
authors.forename: G L
authors.initials: GL
authors.lastname: Hortin
authors.forename: A L
authors.initials: AL
authors.lastname: Summerfield
authors.forename: T R
authors.initials: TR
authors.lastname: Wilhite
authors.forename: C H
authors.initials: CH
authors.lastname: Smith
authors.forename: E L
authors.initials: EL
authors.lastname: Branum
authors.forename: J F
authors.initials: JF
authors.lastname: O'Brien
authors.forename: M
authors.initials: M
authors.lastname: Landt
mesh_terms: D000681:Amylases / Q000097:blood* / Q000276:immunology*; D001323:Autoantibodies / Q000097:blood*; D002850:Chromatography, Gel; D004587:Electrophoresis, Agar Gel; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods* / Q000706:statistics & numerical data; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D012680:Sensitivity and Specificity
chemical_list: D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D000681:Amylases; C001663:macroamylase