PBMCs were stimulated for as above in the presence of 2.5µg/ml anti-CD107α, 1.25µg/ml anti-CD107b (BD Bioscience) and 10µM TAPI-2 (VWR International, West Sussex, UK). Following stimulation, cells were resuspended in cytometry buffer (PBS + 0.05% sodium azide + 2mM EDTA + 2% fetal calf serum) and stained with isotope-tagged antibodies before being acquisition on the CyTOF as previously described19 (link).