Quantitative indicators of TREC and KREC as predictors of the severity of acute respiratory infections in children

Аmphocyte production and indirectly reflect the state of the adaptive immune system. Their concentration in dried blood spots can be determined by quantitative polymerase chain reaction (qPCR). Currently, these markers are used for neonatal screening of primary immunodeficiency conditions. Objective: To assess TREC and KREC levels in children aged 1 to 17 years with acute respiratory infections to predict disease severity. Material and methods. A retrospective study was conducted at Children’s City Clinical Hospital No.9 named after G.N. Speransky. The study included 180 children with acute respiratory infections (105 with community-acquired pneumonia; 75 with acute respiratory viral infections) and 90 healthy children as a control group. TREC and KREC concentrations were determined in dried venous blood spots using quantitative real-time PCR. Results. TREC and KREC concentrations in children with acute respiratory infections were statistically significantly lower compared to the control group (p < 0.05). The discriminatory ability of TREC concentration was higher than that of KREC (TREC: AUC > 0.84 for all age groups; KREC: AUC 0.73 – 0.79). Children with the lowest TREC levels (first quartile) were hospitalized earlier from disease onset and had longer hospital stays. The lowest TREC levels were associated with higher incidence of respiratory failure and elevated C-reactive protein levels. Conclusion. Children with acute respiratory infections show statistically significant reduction in both TREC and KREC concentrations. Low TREC levels are prognostically unfavorable factors associated with more severe disease course.