Assessing assay absorption artefacts in in vitro cell responses to particles

In this study, we assessed the issue of coal particles absorbing extracellular proteins and tested the effects of different culture conditions and processing strategies to address this issue. Our data show that there is no effective strategy to solve this problem. We agree with previous reports that cytokine binding experiments should be performed to implement appropriate correction factors in order to calculate the accurate production of secreted cytokines in the supernatant of cell culture experiments. This is an underappreciated issue in many published studies on the comparative potency of particles from different sources.