TRIM21, an enzyme involved in intracellular substrate degradation, can recognize viruses and bacteria that enter the cytosol when they are coated with antibodies. Just as it tags complex molecules for elimination, it can direct these infectious microorganisms to lysosomes through a mechanism its discoverers have termed antibody-directed xenophagy (ADX). Scientists at the Medical Research Council (MRC) Laboratory of Molecular Biology (LMB) in Cambridge, U.K., have identified the genes involved in this antibody-dependent degradation pathway, which acts as an antimicrobial process, and reported their findings in Molecular Cell on June 4, 2026.