To investigate whether exposure to a 1950 MHz W-CDMA radiofrequency field induces activation of microglial cells at the exposure limit of the average whole-body SAR levels of up to 2 W/kg, changes in major histocompatibility complex (MHC) class II expression and cytokine production in microglial cells were evaluated.
Major histocompatibility complex (MHC) class II is considered the most common marker for activated microglial cells in vivo and in vitro.
Primary cultures of microglial cells (= immune cells of central nervous system) were prepared from neonatal rats. After exposure, the cell cultures were transferred to an incubator and maintained for 24 or 72 h. Positive control cells were treated with lipopolysaccharide or interferon-gamma.
|Exposure duration||continuous for 2 hr|
Exposure to W-CDMA radiofrequency fields (at SAR values of 0.2, 0.8, and 2.0 W/kg) failed to induce MHC class II expression in microglial cells. Furthermore, no increase in production of cytokines in the cell cultures following exposure were observed.
Based on these results, the authors conclude that radiofrequency field exposure does not affect or activate microglial cells in the brain and that exposure to radiofrequency fields may not function as a direct signal of microglial activation.