Until now, the immune sensor TLR8 has remained in the shadows of science. A research team has now discovered how this sensor plays an important role in defending human cells against intruders. The enzymes RNaseT2 and RNase2 cut ribonucleic acids (RNAs) of bacteria into small fragments that are as characteristic as a thumbprint. Only then can TLR8 recognize the dangerous pathogens and initiate countermeasures.