What does the term 'bystander effect' in radiation biology refer to?

The term 'bystander effect' in radiation biology refers to the phenomenon where cells that have not been directly irradiated still exhibit effects as a result of their neighboring cells receiving radiation. This indicates that the impact of radiation exposure is not limited to just the irradiated cells; instead, it can also influence adjacent cells through various mechanisms, such as signaling pathways, inflammatory responses, or the release of reactive species. This effect highlights the complexity of radiation interactions within tissues and underlines the importance of considering not just the directly exposed cells, but also those in proximity that may convey or receive biological signals.