Usefulness of Lymphokine‐activated Killer Cells Generated from Bone Marrow Mononuclear Cells for the Purging of Residual Tumor Cells in Peripheral Blood Stem Cell Graft

Lymphokine‐activated killer (LAK) cells were generated from bone marrow mononuclear cells (BM), and the usefulness of the BM‐LAK for purging of residual tumor cells in autologous peripheral blood stem cell (PBSC) graft was determined. The BM and peripheral blood lymphocytes (PBL) were obtained from the same bone marrow donors. The BM‐LAK and PBL‐LAK were generated by incubation with interleukin‐2 for 7 days. The BM‐LAK demonstrated higher killer activity against a lymphoma cell line Raji than the PBL‐LAK. The BM‐LAK also had a higher percentage of CD4(‐)CD8(‐)CD16(+) cells than the PBL‐LAK, which suggests that their high killer activity is related to these cells. The BM‐LAK did not show any killer activity against the PBSC graft. However, they killed tumor cells which contaminated the PBSC graft, and in particular, killed chimeric ber/abI messenger RNA‐positive residual leukemic cells. These results suggest that the BM‐LAK may be applicable for purging. As the BM‐LAK possess higher killer activity than the PBL‐LAK, they may be more useful than the PBL‐LAK.