ABSTRACT
TSH receptor (TSHR) autoantibody (TRAb) is the serological hallmark of Graves' disease (GD). Third-generation enzyme-linked immunosorbent assays (ELISAs) using monoclonal TRAbs instead of TSH have been found useful for TRAb analysis recently. For the first time, a mouse monoclonal antibody (mAb) against TSHR was analyzed for TRAb detection and compared with human mAb M22 and TSH by the same competitive binding assay technique. A mouse monoclonal antibody (T7) binding to the TSH receptor and inhibiting TSH binding was generated and used for TRAb analysis in a third-generation ELISA. Obtained TRAb levels were compared with a second-generation TRAb assay employing bovine TSH and a third-generation assay with human mAb M22 as TSHR-binding reagents by investigating 89 patients with GD, 56 with Hashimoto's thyroiditis (HT), 73 with non-autoimmune thyroid diseases, 17 with rheumatoid arthritis, and 100 healthy subjects. The T7-based TRAb ELISA did not reveal a significantly different assay performance (area under the curve [AUC]) in contrast to the TSH and M22-based TRAb ELISAs by receiver operating characteristic (ROC) curve analysis (AUC-T7 0.967, AUC-TSH 0.972, AUC-M22 0.958, p > 0.05, respectively). After adjustment of cutoffs by ROC, all three TRAb ELISAs demonstrated sensitivities and specificities above 89.9% and 96.0%, respectively. Both third-generation TRAb ELISAs showed a tendency for a higher prevalence of TRAb positives in HT in contrast to the second-generation ELISA. Mouse mAbs against the TSHR may be used for the reliable detection of TRAb by third-generation TRAb ELISA. The earlier reported higher sensitivity of third-generation TRAb ELISA in GD needs to be considered in the context of a slightly lower specificity regarding HT.
Subject(s)
Antibodies, Monoclonal/immunology , Enzyme-Linked Immunosorbent Assay/methods , Immunoassay/methods , Immunoglobulins, Thyroid-Stimulating/immunology , Receptors, Thyrotropin/immunology , Animals , Arthritis, Rheumatoid/immunology , Female , Graves Disease/immunology , Hashimoto Disease/immunology , Humans , Male , Mice , Middle Aged , ROC Curve , Sensitivity and Specificity , Thyroiditis, Autoimmune/immunologyABSTRACT
BACKGROUND: Glycoprotein 2 (GP2), the pancreatic major zymogen granule membrane glycoprotein, was reported to be elevated in acute pancreatitis in animal models. METHODS: Enzyme-linked immunosorbent assays (ELISAs) were developed to evaluate human glycoprotein 2 isoform alpha (GP2a) and total GP2 (GP2t) as specific markers for acute pancreatitis in sera of 153 patients with acute pancreatitis, 26 with chronic pancreatitis, 125 with pancreatic neoplasms, 324 with non-pancreatic neoplasms, 109 patients with liver/biliary disease, 67 with gastrointestinal disease, and 101 healthy subjects. GP2a and GP2t levels were correlated with procalcitonin and C-reactive protein in 152 and 146 follow-up samples of acute pancreatitis patients, respectively. RESULTS: The GP2a ELISA revealed a significantly higher assay accuracy in contrast to the GP2t assay (sensitivity ≤3 disease days: 91.7%, specificity: 96.7%, positive likelihood ratio [LR+]: 24.6, LR-: 0.09). GP2a and GP2t levels as well as prevalences were significantly elevated in early acute pancreatitis (≤3 disease days) compared to all control cohorts (p<0.05, respectively). GP2a and GP2t levels were significantly higher in patients with severe acute pancreatitis at admission compared with mild cases (p<0.05, respectively). Odds ratio for GP2a regarding mild vs. severe acute pancreatitis with lethal outcome was 7.8 on admission (p=0.0222). GP2a and GP2t levels were significantly correlated with procalcitonin [Spearman's rank coefficient of correlation (ρ)=0.21, 0.26; p=0.0110, 0.0012; respectively] and C-reactive protein (ρ=0.37, 0.40; p<0.0001; respectively). CONCLUSIONS: Serum GP2a is a specific marker of acute pancreatitis and analysis of GP2a can aid in the differential diagnosis of acute upper abdominal pain and prognosis of severe acute pancreatitis.
