**2.3 Target lymphoma and leukemia cells**

The human malignant B-lymphoblastoid cell lines such as Daudi/ Raji and erythroleukemia cell line K562, known as "LAK- sensitive" and "reference cells" in cytotoxicity studies, were utilized in this study. In several experiments we also utilized LAK- resistant human acute myeloid leukemia (AML) cell lines (HL-60, DAMI and Meg-01) and discarded AML patient samples were used. All cell lines were obtained from ATCC (Manassas, VA) and maintained in RPMI 1640 culture media, supplemented with 10% FBS. Before coincubation, target and effector cell viability were determined by the trypan blue exclusion test; a viability of 90% was required to proceed.
