Monocyte-induced NK cell inactivation: role of reactive oxygen and nitrogen metabolites.

Here in a co-cultivation system of natural killer (NK) cells and K562 cells, monocytes (MO) and/or interleukin (IL)-2/phytohemagglutinin (PHA) were administered. After MO were administered, reactive oxygen metabolites (ROM)/reactive nitrogen metabolites (RNM) productions increased, while tumor necrosis factor (TNF)-β/interferon (IFN)-γ levels and NK cell cytotoxicity (NCC) decreased, the changes of which after administering tiopronin (TIP) or glutamylcysteinylglycine (GSH) were opposite. In conclusions, the activated MO could inhibit the NK cell activity to kill K562 cell by secreting ROM and RNM. And TIP and GSH could scavenge both ROM and RNM to reverse the inhibitory effect of MO.