The functional capacity of differentiated K-562 leukemia cells

K-562 cells are undifferentiated blast cells developed from the pleural effusion ofa patient with chronic myelogenous leukemia(CML) The properties ofthepleiotropically diverse K-562 cell line mimic the hematopoietic divergence of malignant blast cells found in CML cell populations Subclones of the original passage maintain the potential to differentiate along early erythrocytic, myelocytic, lymphocytic,megakaryocytic and monocytic lineages This dissertation provides evidence that K-562 sublmes can be induced to acquire characteristics of monocytic, megakaryocytic orgranulocytic differentiation, rendering them functionally competent mediators of several immune processes K-562 cells co-cultured with the tumor promoter phorbol 12-myristate 13-acetate (PMA) presented properties ofthe megakaryoblastic and monocytic lineages Differentiated K-562 cells maintained functional attributes, as measured by the production ofthe inflammatory mterleukm IL-ip, at both the protein and mRNA levels The synergistic action of IL-la, which is constitutively elaborated by K-562 cells, andEL-lP can function to promotethe stimulation of lymphocytes To illustrate this effect, it was demonstrated that PMA-treated K-562 cells were functional replacements formonocytes in the activation of purified CD3+CD4+lymphocytes The activated CD3+CD4+lymphocytes produced IL-4 but not IFN-y or IL-10, suggesting a polarized type 2 immune response A shift from the type 1 immune response observed in patients during the chronic phase of CML to a type 2 response could engender a systemic immune dysregulation allowing for accelerated pathogenesis K-562 cells, induced to differentiate with PMA,likewise alter CD56+ large granular lymphocyte(LGL) conjugate formationand cytolytic response Three-color flow cytometry was used to illustrate that differentiated CD61-expressing K-562 cells have a significantly impaired CD56+LGL-bmdmg efficiency To explore the ability of pluripotential K-562 cells to undergo early myelocytic differentiation, the cells were grown m HL-60 growth-conditioned media(GCM) After24 hours of culture,40-50% of the K-562 cells acquired attributes of the granulocytic lineage, as measured by the production of myeloperoxidase(MPO)enzyme and MPOmRNA It was concluded the K-562 leukemia sublines can be used as a model system for the in vitro analysis of how the differentiation-inducible modification of blastic leukemia cells can influence local and systemic immunity.