Bipotential cell differentiation of KU-812: evidence of a hybrid cell line that differentiates into basophils and macrophage-like cells.

KU-812-F is a subclone of KU-812, which has cytological features similar to the parent clone, and which carries the Philadelphia chromosome. We studied the effects of various chemical agents and serum-free culture (SF-C) condition on its differentiation. The KU-812-F subclone differentiated into macrophage-like cells with phorbol myristate acetate (PMA), but not with other agents. Unexpectedly, under SF-C, KU-812-F cells differentiated into mature basophil-like cells, and the histamine content of cell lysates increased in proportion to maturation. The addition of the condensed supernatant of SF-C promoted the cloning efficiency of KU-812-F cells in semisolid SF-C, whereas the cloning efficiency was reduced in SF-C alone. KU-812-F cells expressed myelomonocytic antigens. Additionally, My4 was induced with PMA and SF-C, but less often. HLA-DR was not expressed in any culture conditions, despite blastic morphology of KU-812-F cells or macrophage-like cells induced with PMA. The IgE receptor could not be demonstrated under any conditions. Correspondingly, immature and mature KU-812-F cells did not respond to anti-IgE or concanavalin A (con A), while histamine release was induced with PMA. In conclusion, KU-812-F belongs to the myeloid cell lineage and is at least a bipotential cell that can differentiate into basophils and macrophage-like cells. Although the functions appear to be dissimilar to those of normal basophils, the KU-812-F cell line may be a good model for basophil differentiation. Moreover, KU-812-F cells may provide new insights because they grow in semisolid culture by an autostimulating mechanism.