Dear Julieta, for us 50ng/ml to 100ng/ml for 2-3h incubation works well with differentiated THP-1 macrophages. You need to check different concentration (better in range 10-100ng/ml) for your preferred time interval and perform Trypan blue/MTT assay for ensuring Cell Viability. Also, as per our experience, its not necessary that a high concentration with induce more ROS. There will be plateau phase.