Effects on in vitro tumor growth of macrophages isolated from human ascitic ovarian tumors

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Abstract
Macrophages were isolated from 22 human ascitic ovarian epithelial tumors and their growth‐inhibitory capacity was tested using as targets the following in vitro tumor cell lines: murlne TLX9 lymphoma and FS6 sarcoma; human myeloid K562 leukemia and human E cell line derived from an ovarian carcinoma. Macrophage preparations were heterogeneous in their interaction with tumor target cells, and assay conditions, such as the type of target cell, incubation time, and attacker to target cell (A:T) ratio critically affected the evaluation of the cytotoxic potential of tumor‐associated macrophages. At an A:T ratio of 7:1 no cytostatic activity on TLX9 and K562 cells was ever observed, but in the presence of specific antibody 8 out of 12 macrophage preparations tested showed significant antibody‐dependent cytotoxicity on TLX9 lymphoma cells. Macrophage preparations from two patients significantly inhibited growth of the FS6 sarcoma and a cytostatic activity on E cells was observed in five additional patients. Significant stimulation of the proliferative capacity of at least one of the target cell lines was observed in 11 subjects at an A:T ratio of 7:1. In 12 patients, macrophage cytostatic activity on E cells was also tested at an A:T ratio of 35:1; eight out of 12 preparations showed significant cytotoxicity under these conditions. When the same subject was repeatedly tested at short intervals the same pattern of inhibition or stimulation of tumor growth was observed.