Methods for preparing T cell populations useful for a variety of purposes requiring a highly active, long-lived T cell population. The T cell populations are enriched for: nave T cells (TN), memory stem cells (TSCM) and central memory T cells (TCM). These cell populations can be derived from peripheral blood mononuclear cells (PBMC) by both: 1) depleting unwanted cell populations such as CD14 expressing myeloid cells and CD25 expressing cells; and 2) enriching for CD62L expressing memory and nave T cells.

The present invention provides cellular tags including an extracellular region, a transmembrane region, and an optional intracellular region. The extracellular region comprises an IL5 receptor alpha (IL5Ra) sequence linked to a transmembrane domain, and the recombinant polypeptide cannot function in signal transduction. The cellular tags can be operably linked to transgenes. The expression of the cellular tag allows identification, detection, selection, and ablation of cells expressing the transgene and the cellular tag. In some embodiments the genetically modified host cell comprises a transgene comprising a polynucleotide coding for a chimeric antigen receptor comprising a ligand binding domain, and a polynucleotide coding for a cellular tag. Pharmaceutical formulations produced by the method, and methods of using the same, are also described.