The specific aims of the National Hematopoietic Progenitor Cell Processing Core remain similar to those from the previous PEGT grant period, to provide NIH-funded investigators with large numbers of enriched human hematopoietic stem cells or other cell populations to facilitate their basic research and pre-clinical studies. The Core will accomplish this by first procuring sufficient amounts of starting material for large-scale processing and cell selection. The Core operates a donor recruitment program to obtain G-CSF mobilized and non-mobilized collections from normal volunteers, and also obtains cadaveric bone marrow from the Northwest Tissue Center and National Disease Research Interchange. The Core processes these collections to obtain large numbers of enriched cell subsets, the types of selections offered include CD34, CD14, CD19, CD22, CDS, CD4, or CDS. The Core characterizes these cells by 3 or 4-color flow cytometry, cryopreserves aliquots for long-term storage, and ships components to requesting investigators. During the previous PEGT the Core performed over 80 large-scale enrichments for CD34, with average final purities >90% and yields of 60%. Additional selections for CD14 (n=40) and T-cells (n=20) have also been performed, with even higher final purities and yields. The Core has distributed over 3,500 vials of enriched cells to more than 60 different investigators from more than 30 institutions, at a greatly reduced cost relative to commercial suppliers. In summary, this Core will continue to provide a unique and critical service in support of NIH funded research, supplying investigators with large numbers of enriched cell populations for in vitro experimentation, animal model testing, and pre-clinical evaluations.