An in vitro study on influence of intravenous immunoglobulin on function of T cells in cord blood of preterm infants

Objective To observe the influence of different doses of intravenous immunoglobulin (IVIG) on function of T cells in cord blood of premature infants and to explore the immunomodulating mechanism of IVIG.Methods Cord blood mononuclear cells (CBMC) were isolated by density gradient centrifugation method from 15 preterm infants born between June 1,2011 to December 31,2011 at 32 34 gestational weeks.Three groups were formed according to the concentrations of IVIG used for CMBC culturing in vitro (Group A,6 mg/ml; Group B,9 mg/ml; Group C,12 mg/ml).After 72 hours in sterile conditions,the levels of IFN 7,IL 4,IL-10 and TGF β1 in the supernatant were determined by enzyme-linked immunosorbent assay.The expression of CD4+ CD25+ Foxp3+ Treg cells was examined by fluorescent activated cell sorter.Differences among groups were compared by one way analysis of variance.For comparison between two groups,LSD test was used.Results (1) The level of IFN γ secreted by CBMC in Group C was 0.03 ± 0.02,which was much lower than that in Group A(0.18±0.08) and Group B(0.13±0.05) (F=5.72,both P＜0.01).The level of IFN-γ in Group B and Group A did not show statistical difference (P＞0.05).Compared with Group A(0.03±0.01),the level of IL4 was much lower in Group B (0.02±0.01) and Group C(0.01±0.01) (F=20.38,both P＜0.01),while no significant difference was shown between Group B and Group C (P＞0.05).(2) No significant difference was found in the expression of CD4+CD25+Foxp3+Treg cells among different groups (F 0.67,P＞0.05).(3) The level of IL 10 in Group C was 3.02 ± 3.79,which was significantly lower than that in Group A (10.78±5.44) and Group B (6.90±4.64)(F=4.68,P＜0.01 and 0.05).The level of IL-10 inGroup B was still lower than that in Group A (P＜0.05).The levels of TGF-β1 in Group C(8.44± 13.71) and Group B(16.15 ±13.94) were significantly lower than that in Group A(30.23 ± 16.32) (F=5.22,P＜0.01,P＜0.05),but there was no significant difference between Group B and Group C (P＞0.05).Conclusions IVIG might inhibit the function of Th cells in CBMC of preterm infants in a dose dependent manner.IVIG could inhibit the function of natural Treg cells by regulating the secretion of cytokines IL-10 and TGF-β1 in a dose dependent effect. Key words: Immunoglobulins, intravenous ;  Fetal blood ;  T-lymphocytes ;  Infant, premature