The changes of immunin function in pediatric patients with severe sepsis

Objective To investigate the association of immunological indicators with the severity and prognosis of pediatric patients with severe sepsis. Methods We enrolled 82 pediatric patients with severe sepsis admitted to pediatric intensive care unit (PICU) at Shanghai Children′s Hospital between March 2013 and February 2017 as septic group.Fifteen healthy children served as control group.The blood samples were collected within 24 hours after admission and on day 7 after treatment.The levels of immunoglobulin (IgG, IgM and IgA) were analyzed by automatic special protein analyzer, and the proportion of T-lymphocyte subgroup (CD3+ , CD4+ , CD8+ and CD19+ ) and natural killer (NK) cells (CD16+ and CD56+ ) in peripheral blood were detected by flow-cytometry. Results The levels of IgG, IgM and IgA had no statistical differences between septic group and control group(P>0.05). Interestingly, the proportion of NK cells in pediatric patients with severe sepsis was significantly lower compared to the control group, and the number of NK cells was significantly increased after 7 days treatment compared with that within 24 hours after admission[(3.7±1.9)% vs.(11.5±1.9)%, P<0.05]. In addition, the proportions of T-lymphocyte subgroups including CD3+ , CD4+ and CD8+ were significantly decreased in patients of septic group compared with control group[(62.8±8.5)% vs.(70.9±2.3)%, (33.3±7.0)% vs.(39.8±1.8)% and(22.6±2.8)% vs.(34.8±15.6)%, respectively, all P<0.05]. Moreover, the proportions of NK cells, CD3+ and CD4+ T lymphocytes subsets in peripheral blood of patients with severe sepsis were positively associated with pediatric critical illness score(P<0.05), and negatively associated with pediatric risk of mortality score Ⅲ and the number of dysfunction organs(all P<0.05). Furthermore, the proportions of NK cells and CD3+ and CD4+ T lymphocytes in peripheral blood of non-survivor with severe sepsis were significantly lower than those in the survivor[(1.5±0.5)% vs.(4.7±1.4)%, (55.1±5.0)% vs.(66.4±7.4)%, (29.7±5.2)% vs.(35.0±7.2), P< 0.05]. Conclusion The proportion of NK cells and CD3+ and CD4+ T lymphocytes subsets in peripheral blood decreases in pediatric patients with severe sepsis, which is associated with severity and prognosis of severe sepsis. Key words: Severe sepsis; Immunoglobulin; T-lymphocytes subsets; Natural killer; Children,