Antibody-based signal amplification for single-cell proteomics by mass spectrometry

Single-cell proteomics by mass spectrometry (scp-MS) detects thousands of proteins per cell, yet low-abundant proteins routinely detected by antibody-based methods are challenging to quantify in the single-cell proteome. To address this, we developed antibody peptide tags (AbTags) - MS detectable tandem peptide barcodes coupled to antibodies which provide signal amplification, enable absolute quantification, and are quantified alongside endogenous proteomes by scp-MS. As proof-of-concept, AbTags quantify cytokine-induced PDL1 expression, undetectable by scp-MS.