Treatment protocol and cell engraftment. Number of donor natural killer (NK) cells (A), γδ T cells (B), and αβ T cells (C) per microlitre. The individual symbols represent patient samples obtained at the different time points. Peripheral blood lymphocytes were analysed using fluorochrome-labelled TCRαβ, TCRγδ, CD56, and donor-specific HLA antibodies by four-colour FACS analysis. (D) Fold increase is calculated as the ratio of the cell number per microlitre on day 8 to the initial value. (E) Treatment and adoptive transfer of donor innate lymphocytes in patient 3, who had a refractory plasma cell leukaemia. In vivo expansion of HLA-B8+ haploidentical γδ T cells within the HLA-B8- recipient was followed by FACS-based chimerism analysis. Right upper quadrant shows the percentage of donor γδ T cells over time.