Neutrophil granulocytes, a type of immune cell, are indispensable for the defense against pathogens. However, if they migrate into injured tissue, for example into the brain after a stroke, they can promote chronic inflammation and cause long-term damage. To analyse the proteins of neutrophils in sites of inflammation and thus their functional dynamics, it takes millions of these immune cells – a problem, because often only few cells are found in these sites. Researchers at ISAS, the University Hospital Essen and the University of Münster have therefore developed a method that enables mass spectrometric analysis using just 1,000 neutrophils.