The Expression And Clinical Significance Of CD4⁺CD25⁺CD127^low/- Regulatory T Cell In Infants And Neonates Undergoing Major Surgy

Objective: CD4⁺CD25⁺ CD127^low/-regulatory T cells (Treg) play a critical role in suppressing the development of autoimmune disease, in controlling potentially harmful inflammatory responses, and in maintaining immune homeostasis. however,their expression and function after sugery remain unknown.The aim of this study was to examine CD4⁺CD25⁺ CD127^low/-regulatory T cells expression on peripheral blood in infants and neonates undergoing major surgy.Methods:The subjects were 24 patients which include 13 neonates,11 infants.Blood samples were obtained before the operation ,at the end of the operation,and 1,3,7 days after the operation. CD4⁺CD25⁺ CD127^low/- regulatory T cells on peripheral blood (PB),TLR2 and TLR4 expression on peripheral blood mononuclear cells(PBMCs) were analyzed by flow cytometry with IL-17 levels on plasma were analyzed by ELISA.RESULT:1.A significantly increased of Tregs population in neonates was observed by day 1 after operation(P<0.05).And then remained elevated for at least six days. The Tregs population in infants were unchanged at 1 day postoperation but was significantly increased by day 3 after operation (P<0.05), also remained elevated for at least four days. 2.A significantly dereased frequency of TLR2 and TLR4 in infants were observed at the end of operation (P<0.05).and then recoverd to the preperative values on postoperative day 1(P>0.05). TLR2 in neonates showed the same changes with infants ;TLR4 had no significant change compared with preoperative values(P>0.05). 3. The IL-17 levels in neonates was unchanged at the end of operation,1,3 day postoperation but were significantly increased by day 7 after operation(P<0.05). The IL-17 levels in infants were unchanged after operation.Conclusion:The expression of TLR on monocytes in infants and neonates undergoing major surgery were downregulated by operation, with a significantly increased of Tregs population in infants and neonates were observed by day 1 or day 3 after operation,which can suppress immune responses and increase the risk of infection. The IL-17 levels in neonates were significantly increased by day 7 after operation, which suggest neonates may have been undergone bacterial infection.The present study may offer new insights for postoperative modulation of innate immunity and adaptive immunity under surgical stress.