PMA-treated K-562 leukemia cells mediate a TH2-specific expansion of CD4+Tcells in vitro

Highly enriched preparations of human CD3 + CD4 + T-lymphocytes were stimul ated with mitogen or OKT3 to determine the capacity of K-562 cells to funct ion as accessory cells. Phorbol 12-myristate 13-acetate (PMA)-treated K-562 cells were induced to differentiate along the megakaryocytic lineage and c ould supplant monocyte-accessory cell function. Intracytoplasmic analysis o f interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) established that IL -4, and not IFN-gamma, was preferentially produced by the activated lymphoc ytes. This polarized stimulation is compatible with a type 2 or humoral imm une response of purified T cells co-cultured with differentiated K-562 cell s in vitro, and may have implications in immunoregulation due to disease pr ogression. (C) 2000 Elsevier Science Ltd. All rights reserved.