title: Immunoassays for measurement of chromogranin A and pancreastatin-like immunoreactivity in humans: correspondence in patients with neuroendocrine neoplasia.
abstract: Chromogranin A (CgA) is a useful marker of neuroendocrine tumors in humans. Here we describe and compare two immunoassay methods for determination of CgA, a radioimmunoassay (RIA) and an enzyme linked immunoassay (ELISA). The detection limit of the ELISA was lower than that of the RIA method (2 ng/ml versus 10 ng/ml, respectively), though the CgA RIA method covered a wider range than the CgA ELISA (10-920 ng/ml versus 2-500 ng/ml, respectively). There was no cross-reactivity with synthetic human and porcine pancreastatin (PST) in the two assays. There was a significant positive correlation between levels of CgA in sera from patients with carcinoid disease, measured by the two methods (r = 0.9, p < 0.0001), and the values were in the same range. Similarly, serum CgA levels in normal controls were also in the same range when assayed by the two methods. A commercially available porcine PST RIA method was evaluated, especially with respect to the influence of Sep-Pak extraction of serum on the levels of pancreastatin-like immunoreactivity (PST-LI). Ten sera from carcinoid patients were treated with Sep-Pak extraction, and levels of PST-LI were determined in non-extracted and extracted sera. There was a significant positive correlation between the concentrations of PST-LI measured in extracted and non-extracted carcinoid sera (r = 0.9, p < 0.002), and the levels were in the same range. There was also a significant positive correlation between levels of CgA and PST-LI in 49 carcinoid sera (r = 0.8, p < 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Institute of Cancer Research, University of Trondheim, Norway.
authors.forename: U
authors.initials: U
authors.lastname: Syversen
authors.forename: M B
authors.initials: MB
authors.lastname: Jacobsen
authors.forename: D T
authors.initials: DT
authors.lastname: O'Connor
authors.forename: K
authors.initials: K
authors.lastname: Rønning
authors.forename: H L
authors.initials: HL
authors.lastname: Waldum
mesh_terms: D000818:Animals; D000918:Antibody Specificity; D014408:Biomarkers, Tumor; D053379:Chromogranin A; D002864:Chromogranins / Q000032:analysis* / Q000276:immunology / Q000652:urine; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D008303:Malignant Carcinoid Syndrome / Q000652:urine; D009423:Nervous System Neoplasms / Q000276:immunology / Q000378:metabolism*; D009490:Neurosecretory Systems; D010187:Pancreatic Hormones / Q000032:analysis* / Q000276:immunology / Q000652:urine; D011863:Radioimmunoassay; D013552:Swine
chemical_list: D014408:Biomarkers, Tumor; C506150:CHGA protein, human; D053379:Chromogranin A; D002864:Chromogranins; D010187:Pancreatic Hormones; C050836:pancreastatin