Macrophage precursors in ovarian carcinoma

Phenotypic and functional characteristics of mononuclear cells in ovarian carcinoma tumors

By using monoclonal antibodies and flow cytometry, the phenotype and activation state [based on presence of interleukin 2 (IL-2) receptors] were determined on the mononuclear cell (MNC) fraction of ovarian carcinoma tissue from 12 patients. Thymidine incorporation response to IL-2 and phytohemagglutinin stimulation was measured in five cases. By FACS analysis, tumor MNCs contained 79% T cells, 11% monocytes/macrophages, 5% B cells, and 5% natural killer cells. Similar findings were noted in the patients' peripheral blood MNC population. The respective T-helper:cytotoxic/suppressor ratios in tumor and blood MNC populations were less than 1 and approximately 2. The percentage of IL-2 receptor-positive cells was low in both populations. The proliferative response of tumor MNCs was lower than that of blood MNCs from patients and from normal volunteers. These results suggest an intratumor immune suppression, perhaps secondary to the absence of a specific responder population or to the presence of suppressor cells or a soluble factor secreted by the tumor that directly suppresses or affects MNC transport into and out of the tumor.

Ability of cancer patients' macrophages to kill autologous tumor targets. Effect of prostaglandin inhibitors on cytotoxicity

Monocyte-derived macrophages isolated from the peripheral blood of 17 patients with cancer were studied for their cytotoxic effects on a sensitive allogeneic tumor target as well as autologous tumor cells. Macrophages from four of the cancer patients were cytotoxic towards the allogeneic tumor target. Five patients had macrophages which were cytotoxic towards the autologous targets. When indomethacin, a prostaglandin inhibitor, was added to the noncytotoxic macrophages during the cytotoxicity assay, macrophages from 5 of the 11 cancer patients studied became cytotoxic for the allogeneic target, and macrophages from 4 of the 11 patients became cytotoxic for the autologous tumor cells. However, it was also noted that those cancer patients who possessed cytotoxic macrophaged in the absence of indomethacin, became noncytotoxic towards the tumor cells after addition of indomethacin. These results indicate that addition of indomethacin to cytotoxic macrophages suppresses macrophage mediated cytotoxicity whereas addition of indomethacin to noncytotoxic macrophages greatly enhances macrophage mediated cytotoxicity. This theory was further substantiated when it was observed that the cytotoxic macrophages obtained from normal donors also became noncytotoxic for a sensitive tumor cell line after the addition of indomethacin during the cytotoxicity assay.

Cytotoxicity of cancer patient's macrophages for tumor cells

Monocyte derived macrophages were isolated from the peripheral blood of 66 patients with either breast, colon, gynecological or hematological cancers. The macrophages from the breast and gynecologic cancer patients generally did not acquire enhanced cytotoxicity for human tumor cells after incubation with bacterial lipopolysaccharide (LPS). However, when the macrophages isolated from colon and hematologic cancer patients were studied, more than 50% of these patients possessed cytotoxic macrophages. LPS induced macrophage mediated cytotoxicity was also found to be inhibited by factors present in many cancer patient's plasma. Twenty-three of the 50 cancer patients studied possessed a plasma inhibitor capable of suppressing macrophage mediated cytotoxicity by more than 50%. Furthermore, of these 50 patients, 47 were incapable of killing the tumor cells in vitro either because they possessed nonresponsive macrophages and/or they possessed a plasma inhibitory factor. Thus, although macrophage cytotoxic function may be normal in some patients with cancer, cytotoxicity may be inhibited in some patients by factors in autologous plasma thereby rendering the macrophages ineffective in vivo.

Tumoricidal activity of macrophages isolated from human ascitic and solid ovarian carcinomas: augmentation by interferon, lymphokines and endotoxin

Peripheral blood monocytes and macrophages from ascitic or solid tumors were obtained from 50 patients with advanced (Stage III or IV) ovarian carcinoma. Blood monocytes and peritoneal macrophages from 76 patients undergoing surgery for benign gynecological diseases were used as controls. Macrophages were 30% (range 0.2-6.2) and 2% (range 0.2-4) of mononuclear cell suspensions from ascitic and solid tumors, respectively. Cytolytic activity was measured as release of [3H]-thymidine from prelabelled mKSARU5 (TU5) target cells at an effector to target cell ratio of 20:1. Peripheral blood monocytes and tumor-associated macrophages had baseline cytotoxicity lower than or similar to that of control peripheral blood and peritoneal macrophages respectively. In vitro exposure to partially purified human fibroblast interferon, lymphokine supernatants or endotoxin augmented the cytotoxicity of mononuclear phagocytes, and no significant difference was observed between control and ovarian cancer effector cells from peritoneal effusions. In four patients, macrophages were isolated from the solid tumor or from the malignant effusion and tested in parallel: in two out of four subjects, macrophages from the solid neoplasm showed defective cytotoxicity compared to ascites effector cells from the same subject. When primary ovarian carcinoma cultures were used as targets, tumor cells from two out of five patients tested were relatively resistant to activated macrophage cytotoxicity. Thus, tumor-associated macrophages from ascitic or solid ovarian neoplasms showed no evidence of activation, in terms of spontaneous cytotoxicity or responsiveness to stimuli: it appears unlikely that small numbers of non-activated macrophages present within primary ovarian carcinomas act as a significant mechanism of restraint of neoplastic growth, at least at this anatomical site.