Increase in IL-15 concentration and donor chimerism in lymphoablated recipients after NK-cell infusion. (A) IL-15 concentration was evaluated in the serum of all patients at different time points after NK-cell infusion. Each curve corresponds to one different patient. (B) CD56⁺CD3⁻ cells were enumerated in the PB of all patients by flow cytometry at different time points after NK-cell infusion. Baseline corresponds to the day before chemotherapy was started. The results are the mean ± SD of all patients. (C-D) The percentage of donor chimerism, as tested on whole blood, was evaluated in the PB (C) and BM (D) by VNTR analysis in all treated patients (n = 13). Ten of 13 patients were fully evaluable all over the different time points, whereas in the remaining patients, particularly during the neutropenic phase after chemotherapy, cell concentration did not allow a reliable VNTR analysis. Here are reported the results of all positive patients (n = 7 for PB and n = 4 for BM). In the remaining evaluable patients, no donor chimerism was observed.