To make CMV-specific T cells (Viralym-C cells), small pieces of protein called peptides that come from CMV were mixed with blood cells from healthy donors. These peptides train a kind of white blood cell called T cells to recognize and kill cells that are infected with CMV. These T cells were then grown in special growth factors in special flasks in the lab. Once we made sufficient numbers of cells, we tested them to make sure they recognized cells infected by CMV, and then we froze them.