In Immunopeptidomics We Need a Sniper Instead of a Shotgun

Immunopeptidomics employs the use of mass spectrometry to identify and quantify peptides presented on the surface of cells by major histocompatibility complex (MHC; human leukocyte antigen [HLA], in humans) molecules, an essential component of adaptive immunity. Currently, immunopeptidomics follows the same or similar workflows as the more established field of shotgun proteomics, yet inherent differences between these two fields create significant drawbacks for the former. In this viewpoint, we would like to highlight such technical issues and provide suggestions for novel workflows that would increase peptide sequencing coverage, depth, and confidence, collectively enhancing the capabilities of the field of immunopeptidomics.