Peter Schmeits researched the detection of substances that are toxic to immune cells by culturing different cell lines in plastic containers and exposing them to toxic and non-toxic substances for immune cells. He then measured the effects on the activation of all genes (roughly 22,000 messenger RNAs). This generated new insights into the substances' modes of action. Previous research has identified a group of twenty-five marker genes that can predict the toxicity of a substance for the immune system, which was confirmed in a new experiment using different substances. This alternative method may one day be replicated using animal studies