Strength of binding between leukemic blasts and cytotoxic lymphocytes.

Strength of binding (Sb), a new parameter defined by the ratio of binding capacity and dissociation rate constants, was estimated and used for the characterization of conjugate formation between leukemic blasts and cytotoxic lymphocytes. Lymphokine activated killer (LAK) cells, i.e., interleukin-2 activated peripheral blood lymphocytes (PBL) displayed significantly (P < 0.001) higher Sb with leukemic blasts when compared to fresh, nonactivated PBL. Interaction of both fresh PBL and LAK effector cells with acute myeloid leukemia (AML) blasts was characterized by a significantly (P < 0.05) lower Sb when compared to the K562 cell line. Interaction of LAK effector cells with leukemic cell-lines of lymphoid origin (Daudi, Raji, and HuT78) was characterized by a significantly (P < 0.005) lower Sb than with K562 myeloid cell line. Sb for the interaction of natural killer (NK)-derived CD16+/CD56+ LAK with leukemic blasts was significantly (P < 0.001) higher than that of T-cell-derived CD3+LAK. We conclude that calculation of Sb provides a relatively simple and independent way to evaluate systems of interacting cells at a single time and may be used to compare results between different cell systems and laboratories.