BACKGROUND: Disorders of lymphocyte subpopulations counts and NK cellsmay not only contribute to impaired elimination of pathogens, but also be an important factor in thedevelopment of generalized inflammatory reaction. The aim of the paper was the analysis of subpopulationsof lymphocytes and NK cells in children with sepsis and after recovery. MATERIAL/METHODS: The study comprised25 septic children (17 infants and 8 children aged from 1 to 3 years). The control group consisted of25 healthy children. The study was conducted in the initial phase of sepsis and then repeated 2 to 3months after recovery. In all the children, the percentage and absolute numbers of basic lymphocyte subsetsand NK cells in blood serum were evaluated. RESULTS: In the course of sepsis, the absolute number ofactivated lymphocytes T in the youngest children was higher in comparison with the control group. Afterrecovery, the percentage and absolute counts of CD4 lymphocytes in all the children and CD3/CD4 lymphocytesratio in the youngest children were considerably lower than in the control group. The percentage andabsolute number of NK cells in the youngest children after recovery were higher in comparison with thecontrol group. CONCLUSIONS: In children who underwent sepsis, depression traits of cellular immunityare observed. The occurrence of defensive system disorders after recovery may be an important factorin recurrent infections and creates the necessity of immune system monitoring in children with the historyof sepsis for the purpose of prevention.

Keywords: Case-Control Studies, Child, Preschool, Lymphocyte Subsets, Sepsis