Nonclassical MHC class Ib–restricted cytotoxic T cells monitor antigen processing in the endoplasmic reticulum

The aminopeptidase ERAAP trims peptides loaded onto MHC class I molecules and can be targeted during evasion of the immune response by pathogens. Shastri and colleagues show that inhibition of ERAAP identifies a protective nonclassical MHC presentation pathway involving Qa-1.