Type III interferons in community-acquired pneumonia in children

The relevance of community-acquired pneumonia is due to its widespread prevalence in pediatric practice, due to high level of morbidity and mortality in this pathological condition. Anti-infectious protection is of great importance in prevention of community-acquired pneumonia, primarily, the state of innate immunity, including cellular and humoral immune response. Among the factors of innate immunity, cytokines play an important role, being the most important mediators that control and regulate immune and inflammatory responses via complex networks and serve as biomarkers of many diseases. A single cytokine may be secreted by different cells and exhibit both pro-inflammatory and anti-inflammatory activity, depending on its context, thus causing multiple immune responses. Among cytokines, interferons play a significant role, being among sufficient factors of innate immunity. The study determined the level of type III interferons (IFNλ2 (IL-28A) and IFNλ3 (IL-28B)) in blood serum of 117 children with community-acquired pneumonia aged 1 to 18 years with an X-ray confirmed diagnosis of community-acquired pneumonia, hospitalized at the Departments of Respiratory Infections at the Pediatric Clinical Hospitals No. 7 and 8 in Chelyabinsk. All children were represented by 3 age groups, according to the generally accepted critical periods of immune system maturation, i.e., 1 to 3 years old; 4 to 7, and 8 to 18 years old. The comparison group was recruited during routine medical examination of healthy children and consisted of 28 subjects who did not show any signs of acute respiratory viral infection at the time of examination, and had no detectable chronic diseases. The purpose of this study was to determine the concentration of type III interferons in blood serum of children with community-acquired pneumonia at different ages, and to assess changes in indices, depending on the severity of the disease. According to the results of the study, we have revealed that the serum concentrations of type III interferons, in particular, IFNλ2 (IL-28A) and IFNλ3 (IL-28B) among the children with community-acquired pneumonia, were significantly higher in the subgroup of children with severe pneumonia. Significant differences in concentrations of type III interferons were shown for the children in different age groups, which may be due to peculiar features of immune system activation at different age periods and immaturity of immune system in children.