Selective expansion of NK/LAK from IL-2–activated PBSCs.

PBSCs were incubated in 24-well plates at 1 × 10⁶ T/NK (CD3⁺/CD56⁺CD3⁻) lymphocytes per milliliter and cultured for 7 days in RPMI 1640 with 10% human AB serum supplemented with rIL-2 (1000 IU/mL). (A) Immunophenotyping of PBSC cultures was performed at day 0 (left vertical panel), day 4 (center vertical panel), and day 7 (right vertical panel) by 4-color flow cytometry with the use of the combinations of FITC-, PE-, PerCP-, and APC-conjugated mAbs CD4/CD8/CD3/CD45, CD25/CD56/CD3/CD45, and HLA-DR/CD69/CD3/CD45. One representative experiment showing the expansion of CD56^brightCD3⁻ NK/LAK cells is presented. (B,C) Cytolytic activity of cultures at days 2 (white bars), 4 (gray bars), and 7 (black bars), depicted as the percentage of lysis at a 6.25:1 E/T ratio against tumor targets. In panel B, results are presented as mean ± SEM (n = 10) percentage of lysis against K562, Daudi, and the 2 NB cell lines IGR-NB1 and IGR-NB2. Panel C shows a representative experiment displaying the cytolytic activity of immunopurified CD3⁻CD56⁺ NK/LAK cells on autologous NB tumor cells freshly isolated from invaded bone marrow (AUTO-NB) compared with lysis of allogeneic targets (NB1 and DAUDI).