Antioxidative and immunomodulatory role of melatonin, sodium selenite, N-acetyl-L-cysteine and quercetin on human umbilical blood.

We have previously reported on the DNA oxidative damage and oxygen stress in healthy term neonates. The aim of the present study was to investigate the antioxidative and immunomodulatory role of melatonin, sodium selenite, N-acetyl-L-cysteine and quercetin on umbilical blood. The single cell gel electrophoresis (comet) assay was used for DNA oxidative damage. The lymphocytes proliferation and natural killer (NK) activity in umbilical blood were assayed by (3)[H]-thymidine uptaken and MTT methods. Results using comet assay showed protection by melatonin, N-acetyl-L-cysteine (NAC) and quercetin, and a protective and damaging effect by selenite sodium. Melatonin, sodium selenite, NAC and quercetin greatly promoted the lymphocytes proliferation to IL-2. NK activity of the umbilical blood was significantly increased by melatonin and sodium selenite, but was not affected by NAC and quercetin. These data suggest that antioxidants are able to protect umbilical blood mononuclear cells against oxygen stress and affect oxygen stress mediated immune function inhibition of umbilical blood. These results will supply new experimental data for using umbilical blood to treat diseases.