Activation-induced cell death and total Akt content of granulocytes show a biphasic course after low-dose radiation.

Low-dose radiation (single doses from 0.3 to 1.0 Gy) in clinical practice is mostly used to treat patients with several inflammatory diseases and painful degenerative disorders. Low-dose radiation is known to exert anti-inflammatory effects. However, the molecular and cellular mechanism are not fully analysed and most of the observed effects are based on empirical studies. We investigated the effects of low-dose radiation on the activation-induced cell death of polymorph nuclear granulocytes (PMN). A biphasic appearance of cell death in irradiated PMN was observed, displaying a relative maximum at 0.3 Gy and minimum at 0.5 Gy, respectively. This biphasic course of cell death was coincident with the protein level of total cellular Akt. We conclude that low-dose radiation exerts immunomodulatory effects on PMN contributing to the observed anti-inflammatory effects in clinical applications.