SOCE is induced in monocytes in response to bacterial pathogens. In naïve mice or human blood monocytes, the redox sensitive ORAI1 is the predominant isoform. However, during infection, monocytes upregulate expression of the redox-insensitive isoform ORAI3, lending the CRAC-channel more resistant to ROS-mediated inactivation. This switch is important for calcium entry, ROS production and bacterial killing.