Immune cells fight infectious intruders, for example, or search for incipient cancers. Therefor, they are constantly migrating through the tissues of our body. But in the wrong place, immune cells like neutrophil granulocytes can cause damage: If these white blood cells infiltrate tumours, this is often associated with a poor prognosis for patients. This is why they could benefit from drugs that prevent neutrophils from migrating into tumours. Until now, this migration has been investigated using conventional video microscopy. Researchers (University of Duisburg-Essen, Leibniz-Institut für Analytische Wissenschaften) have developed a microscope for the high throughput analysis of compounds.