Simultaneous flow cytometric measurement of K-562 megakaryocytic differentiation and CD56+large granular lymphocyte cytotoxicity

K-562 cells have the capacity to undergo multi-lineage differentiation, whi ch may be crucial to their ability to serve as target reservoirs for CD56 large granular lymphocytes (LGL). Conventional techniques using chromium r elease assays to measure lymphocyte-mediated cytotoxicity suffer from disad vantages, including radioactive contamination and the inability to simultan eously determine K-562 and/or CD56+ lymphocyte phenotypes. We illustrate he re a three-color flow cytometric method providing for the simultaneous eval uation of K-562-CD56 + LGL binding, K-562 cell viability, and the status of K-562 cell differentiation. Phorbol 12-myristate 13-acetate (PMA) engender s megakaryocytic differentiation in K-562 cell populations, as measured by presentation of the beta (3) integrin (gpIIIa, CD61), while maintaining a n egative expression of MHC-I and MHC-II molecules. Using the auto-fluorescen ce of K-562 cells, flow cytometry can be used to demonstrate a significant decrease in CD56 + LGL activity against K-562 cells in populations pre-incu bated with PMA. The capacity of three-color flow cytometry to measure lymph ocyte-target cell binding and cell death kinetics, while simultaneously det ermining target cell phenotype, permits the specific localization of CD61-e xpressing K-562 cells to areas inconsistent with CD56 + LGL-mediated patter ns of lysis. (C) 2001 Elsevier Science B.V. All rights reserved.