library_construction_protocol: Cryopreserved cells were thawed and dead cells removed by lymphoprep density gradient centrifugation. Cells were enumerated on a hemocytometer. The cells from individual donors were labelled with a unique sample tag identifier using the BD Single-Cell Multiplexing Kit. Donors were pooled in equal ratios, with the aim of loading 4000-5000 cells per donor onto a cartridge. Donors 1-4 and 5-8 were run on independent cartridges using a custom designed 701 gene panel. Manufacturers protocols were followed throughout Libraries were constructed using the BD-Rhapsody Single-Cell Multiplexing kit.