Thyroid
Abstract E-Poster Presentation
Jeffery A. Houtz, BS
Scientific Affairs
Quidel Corp.
Athens, Ohio, United States
Lynn Miao, MD
Principal Scientist
Quidel Corporation
Athens, Ohio, United States
Lynn Miao, MD
Principal Scientist
Quidel Corporation
Athens, Ohio, United States
Jeffery A. Houtz, BS
Scientific Affairs
Quidel Corp.
Athens, Ohio, United States
Two rapid homogenous bioassays, named as Turbo TSI and Turbo TBI, have been developed to either quantitatively detect Thyroid Stimulating Antibodies (TSAb) or qualitatively detect Thyroid Blocking Antibody (TBAb) in Autoimmune Thyroid Disease (ATID) patient sera. The two bioassays do not require cell culture, sample dilution, washing or cell lysis steps, resulting in a dramatically reduced turnaround time to 60 minutes. This study was designed to demonstrate the high specificity of the two bioassays in comparison with the TSHR Autoantibody (TRAb) ELISA Kit (Kronus).
Methods:
Six serum samples containing the same concentration of human monoclonal thyroid stimulating antibody (M22) with different concentrations of thyroid blocking antibody (K1-70) were prepared. The same sample set was tested by the Turbo TSI and TBI bioassays, as well as the TRAb ELISA concurrently. The TSAb concentration (IU/L) for each sample was measured by the Turbo TSI bioassay and the % Inhibition of luciferase expression for each sample was determined by the Turbo TBI bioassay. Twenty clinical samples obtained from suspected AITD patients were also analyzed by the two bioassays and the IgG fraction was then removed from those clinical samples using NAb™ Protein G Spin Columns (0.2 mL). Both IgG-depleted sera along with purified IgG fractions were tested by either Turbo TSI or TBI bioassay.
Results:
The Turbo TSI Bioassay only detects M22 without cross reacting with K1-70 at 200 ng/mL. The Turbo TBI Bioassay only detects K1-70 without cross reacting with M22 at 50 ng/mL. When both types of the antibodies coexist in the samples, the two bioassays detect either a net stimulatory or a net inhibitory effect of TSI and TBI. Meanwhile, the TRAb ELISA Kit detects combined M22 and K1-70 nonspecifically. Of twenty clinical samples, nine of them were TBAb positive and eleven of them were TSAb positive. After removal of IgG fractions from those samples, the TBI positive samples became negative and the TSI positive samples decreased their TSI concentrations by 72% to 100%. The purified IgG fractions showed either TSI or TBI levels near to their original samples.
Discussion/Conclusion:
The detection of two types of thyroid autoimmune antibodies by the two rapid homogenous bioassays has been demonstrated by the IgG depletion study. The activity of both TSAb and TBAb measured in each bioassay can be removed almost completely by depleting IgG factions from their serum samples and the same level of antibody activity can be detected in the purified IgG fractions. Unlike the TRAb assay, the Turbo TSI and TBI bioassays can distinguish between TSAb and TBAb and detect both antibodies specifically.