Evaluation of interferon gamma release assay to measure t-cell response in COVID-19 patients from intensive care units and inpatient departments

Interferon gamma release assay (IGRA) is an in vitro blood test to measure interferon gamma (IFN-γ) released from antigen-specific T cells after stimulation with pathogen-specific peptides. In this study, it was aimed to investigate the T-cell response using IGRA and to compare various laboratory values in Coronavirus Disease (COVID-19) patients hospitalized either in hospital inpatient departments or in intensive care units. A total of 100 patients (50+50) who were identified as positive for COVID-19 through the molecular method in Selcuk University Faculty of Medicine Infectious Diseases Service and Reanimation Intensive Care Unit were included in the study. IFN-γ levels in blood samples collected from patients were determined using the QuantiFERON Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) (QIAGEN, Germany) kit. The patients' gender, age, c-reactive protein (CRP), aspartate aminotransferase (AST), alanine transaminase (ALT), interleukin (IL)-6, lymphocyte count, procalcitonin, and D-dimer results were obtained from the hospital automation system. Thirty-eight of the IGRA test results were negative, 44 were positive and 18 were inconclusive. The age of patients with negative IGRA test results was significantly higher (p