SiteCELL enables on-site PBMCs purification and cryopreservation for immune single cell profiling of diverse ancestries

Single cell genomics has improved our knowledge of immune function and heterogeneity. In recent years, the steady increase in the number of cells and individuals profiled as part of large multinational projects has enabled the characterization of cellular differences across human populations and ancestries. However, methods for collecting and processing peripheral blood mononuclear cells (PBMCs) for downstream single cell sequencing are difficult to implement in remote and rural settings. This has resulted in a lack of representation of underserved communities across the Global South in current initiatives. Hence, we developed SiteCELL, a method that enables purification and cryopreservation of PBMCs from whole blood at the site of collection using minimal laboratory equipment and without electricity. By comparing matched samples of purified PBMCs, we showed that SiteCELL performs as well as ficoll density gradient (FDG), both in laboratory and rural settings. This method ensures accurate recovery of cell type proportions and excels in reducing stress and minimizing variability across sampling batches. These advantages make it particularly well suited for implementation in challenging settings across countries, thereby enabling the inclusion of underrepresented ancestries in cellular atlases.