A pilot study for the evaluation of an interferon-gamma release assay (IGRA) to measure T-cell immune responses after SARS-CoV-2 infection or vaccination in a unique cloistered cohort

Background: Assessment of T-cell responses to SARS-CoV-2 antigens may be of value to determine long-lasting protection to breakthrough infections or reinfections. Interferon-gamma release assay is a validated method to test cellular immunity in mycobacterial infections and has been proposed for patients with SARS-CoV-2 infection or vaccination. Methods: Quantitative IgG to spike and qualitative IgG to nucleocapsid antigens were determined by chemiluminescence microparticle immunoassay using the Architect® platform (Abbott®), and interferon-gamma release assay against two Qiagen® proprietary mixes of SARS-CoV-2 spike protein (antigen-1 and antigen-2) were performed for a selected group of subjects. Results: A total of 121 subjects in a cloistered institution after a COVID-19 outbreak were studied. IgG-spike levels and interferon-gamma concentration were highest among subjects after two doses of vaccine, followed by patients with a longer history of past COVID-19 and no vaccination. Best cut-off for interferon-gamma assay was 25 IU/μL for all subgroups of individuals and the two sets of SARS-CoV-2 antigens studied. Conclusions: Testing T-cell response may be of clinical utility to determine immunity after exposure to SARS-CoV-2 antigens, with the interferon-gamma concentration of 25 IU/μL as the best cut-off either after infection or vaccination.

IFN-Gamma and IL-2 Secretion after ESAT-6-CFP-10 (EC-610) Fusion Antigen Stimulation from Patients with Active Lung Tuberculosis and Latent Lung Tuberculosis

The Secretion of IFN-Gamma and IL-2 After ESAT-6-CFP-10 Fusion Antigen Stimulation in Active and Latent TB Patients. This study held to discover how immune responses work and to know the pathogenesis of active TB and latent TB patients. This study used PBMC to stimulate T Cells with ESAT-6 and CFP-10 antigen fusion, and measure the level of IFN-gamma and IL-2 with ELISA antibody sandwich (U-Cytech). 16 ml of blood were drawn to 5 tubes. ESAT-6 CFP-20 inducted one tube with QuantiFERON for IFN-gamma assay. The other four tubes were PBMC isolated using Ficoll-Paque, and pre-incubated with stimulation of ESAT-6 CFP-10 fusion antigen for 24-72 hours at 370 C and measured using T-Spot and ELISA reader. We got from this study that there are no significant differences in IFN-gamma levels for both groups with active TB and latent TB. Measurement of IL-2 levels showed significant differences between the two group.