Levels of TREC and KREC molecules significance determining in peripheral blood for predicting the outcome of COVID-19 disease in the acute period

The disease caused by the highly contagious SARS-CoV-2 virus – “novel coronavirus infection (COVID-19)” – had killed more than 6.5 million people at the end of December 2022. The severity of the manifestation of the infectious process varies from asymptomatic forms to rapid progression to life-threatening conditions requiring emergency measures. One of the factors, the severity of which affects the outcome of the disease, is lymphopenia, the cause of which may be a violation of lymphopoiesis. The identification of laboratory markers of a high risk of mortality in patients with COVID-19 plays an important role in improving patient care algorithms and increasing their survival. Levels of TREC and KREC molecules in peripheral blood, respectively, can serve as molecular markers of the severity of T and B lymphopenias. The aim of our work was a comparative analysis of the levels of TREC and KREC molecules in the peripheral blood of surviving and deceased patients with COVID-19. The material was whole blood samples obtained from 1745 people, including: 1028 patients diagnosed with novel coronavirus infection (COVID-19) (ICD-10 code – U07.1), of which 937 patients recovered and 91 died; 717 apparently healthy individuals (control group). The levels of TREC and KREC molecules were assessed by quantitative multiplex Real-time PCR using the TREC/KREC-AMP PS reagent kit (Federal Scientific Research Institute Pasteur, St. Petersburg). Statistically significant differences in the levels of KREC and TREC molecules between the control group and patients, both surviving and deceased, were established. A significant decrease in median concentrations of KREC molecules was shown in patients with a lethal outcome compared with survivors (p = 0.0019, 95% CI). Among the deceased patients, in 63.7% of cases, the levels of TREC or KREC molecules were reduced relative to the corresponding age norms. Of these, in 20.9% of cases, both analytes were reduced in patients. When assessing the diagnostic significance of the levels of the analytes under study for predicting the outcome of the disease, the area under the AUC curve for KREC was 0.63±0.029, which indicates the average strength of the prognostic model of the patient's death depending on the level of KREC in the blood. The constructed model is statistically significant (p = 0.002). Monitoring laboratory parameters of patients with COVID-19, including those who died, allows you to determine the prognostic factors that are most significant for assessing the outcome of the disease. Based on the assessment of the KREC level, a predictive model with high specificity reflects the risk of death in patients with COVID-19. Thus, the quantitative determination of the level of KREC molecules in the peripheral blood can be attributed to the methods of preventive personalized diagnostics aimed at improving the survival of patients.