Fig. 1.

a Allogeneic NK cell products and ex vivo expansion. Total nucleated cell (TNC), CD56⁺/CD3⁻ NK cell and CD3⁺ T cell frequencies (mean ± SEM) in six apheresis products, after CD3 depletion and overnight activation with 1,000 IU/ml IL-2. b CD3 depleted clinical products (n = 6) were tested in Cr₅₁ release cytotoxic assay against K562 targets before and after ex vivo incubation with 1,000 IU/ml IL-2 at E:T ratio as shown (*p < 0.05). c Regulatory T cells increase after NK cell and IL-2 therapy. Patients with refractory lymphoma received pre-infusion chemotherapy, haploidentical donor NK cell infusion and IL-2 × 6 doses. Absolute numbers of regulatory T cells, cytotoxic CD3⁺CD4⁻ lymphocytes, serum levels of tumor necrosis factor receptor 1 and IL-10 are compared at baseline and at day 14. Mean cell frequencies ± SEM of five evaluable patients are shown (*p < 0.05). d Flow cytometric detection of T lymphocytes subsets and Treg in peripheral blood at baseline, days 0 (prior to allogeneic NK cells infusion) and 14 (following IL-2 therapy) are compared. Representative plot from patient #6 is shown