Basic lymphocyte subsets during the post-traumatic period in children

Severe trauma remains a leading cause of disability and mortality among children over 1 year. This study aimed to assess the dynamics of peripheral blood lymphocyte subpopulations in pediatric trauma, depending on severity, complication risks, and general prognosis in pediatric trauma. A total of 118 children with severe mechanical trauma (ISS ≥ 16) were included. According to the Severe Injury Outcomes Scale (OISS), 60 patients had a favorable outcome; 51, with unfavorable outcome, and fatal outcome was documented in 7 cases. On the basis of clinical course, the subgroups with septic complications (PSC, n = 23) and multiple organ dysfunction syndrome (MODS, n = 19) were discerned. Flow cytometric analysis of lymphocyte subpopulations (CD3+, CD19+, NK cells) was conducted on days 1, 3, 5, 7, 10, and 14 post-trauma, with return to age-specific reference values. A comparison group included 34 children with mild or moderate trauma (ISS 16), and a control group consisted of 60 age- and sex-matched healthy children. The laboratory findings revealed a significant and sustained reduction in CD3+, CD19+, and NK lymphocyte counts in children with severe trauma as early as day 1, with partial recovery by days 5-7. In children with mild trauma, these changes were less pronounced. Persistent lymphopenia, especially, in CD3+ and NK cells was significantly associated with MODS, PSC, and poor outcomes. These results confirm the prognostic relevance of dynamic monitoring of lymphocyte subpopulations as sensitive markers of immune dysfunction in the context of severe trauma and its complications. Inclusion of cellular immune parameters into risk stratification protocols may enhance the early identification of children at high risk for adverse outcomes and suggest targeted therapeutic interventions.