Large-scale production of human tumorcytotoxic macrophages grown from blood monocytes of cancer patients.

For adoptive immunotherapy protocols using cells of the macrophage (M phi) system, well differentiated and functionally competent effector cells are required. In this presentation the generation of a large number of M phi grown in vitro from blood monocytes (mo) is reported. Mononuclear cells (MNC) were collected by cytapheresis and subsequent Ficoll centrifugation. Mean yield was 6.9 x 10(9) MNC (range from 3 x 10(9) to 1.2 x 10(10), n = 18) with a mean mo count of 22 +/- 14%. MNC were cultured at 5 x 10(6)/ml in suspension on hydrophobic Teflon foils with 2% autologous serum for 7 days with recombinant human interferon-gamma (rhIFN-gamma) being present for the last 18 h of culture. Cells were harvested and activated mo-derived M phi separated from lymphocytes by counter-current centrifugal elutriation. On average, 42% of mo cultured could be recovered as M phi, the maximal number of M phi generated being 1.7 x 10(9) with a purity of up to 96%. Mo-derived M phi appeared to be mature by their expression of maturation-associated antigens and proved to be cytotoxic to allogeneic tumor targets in vitro. They secreted large quantities of tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6), and granulocyte-macrophage colony stimulating factor (GM-CSF) upon stimulation with endotoxin. Using the technology described, this study revealed that large amounts of tumorcytotoxic M phi can be generated from the peripheral blood of cancer patients to be used in adoptive immunotherapy trials.