ADCC effector cells in a murine adenocarcinoma. I. Evidence for blood-borne bone-marrow-derived monocytes

Cells bearing Fc receptors in human malignant solid tumours

Fc-receptor-bearing cells forming EA rosettes with antibody-coated human erythrocytes (Ripley) were studied in cell suspensions and in purified preparations of mononuclear cells (MC) from 20 human malignant tumours. The EA rosettes were studied in preparations made by cytocentrifugation and the rosette-forming cells identified by their nonspecific-esterase activity and phagocytic capacity. Fc receptors were found on 16 +/- 20% of all cells in the primary cell suspensions. Significantly more tumour-infiltrating lymphocytes had detectable Fc receptors normal control subjects (14 +/- 6%). There was a significant correlation between the proportion of lymphocytes lacking T and B markers (null cells) and the proportion of lymphocytes with Fc receptors. Fc receptors were also found on most tumour-infiltrating macrophages, on some T lymphocytes and polymorphonuclear cells and on a smaller percentage of the tumour cells. The significance of the Fc receptor and its usefulness as a marker of "host infiltration" into the tumours is discussed.

Immunohistologic evidence for the role of antibody and macrophages in regression of the murine T1699 mammary adenocarcinoma

The regression or progression of the T1699 murine mammary adenocarcinoma was analyzed with histologic an immunohistologic techniques to determine the tissue distribution of both macrophages and anti-tumor antibody. Changes in integrity of tumor blood vessels were apparent during tumor growth and regression. Tumors at early stages of growth were invaded in the capsule by multiple vascular branches which later permeated tha tumor. Following the appearance of anti-tumor in the serum, these vessels often showed immune complex deposition which preceded vessel leakage, destruction and hemorrhage. After these changes, tumor cells appeared coated with antibody. Macrophages appeared predominantly in the tumor capsule during early stages of tumor growth, while at later stage they were observed within tumors most prominently near the edge of growing hemorrhagic and necrotic areas. As tumors regressed, connective tissue septation lined by macrophages became apparent. Phagocytosis of seemingly intact tumor cells was common and appeared to account for much of the loss in tumor cell numbers. In immunosuppressed animals (ATXBM,450R) in which tumor progression always occurred, the above features were markedly diminished or absent. This model emphasizes the interplay of many factors in tumor regression. These include immune complex deposition, blood vessel destruction, macrophage infiltration and connective tissue development, all of which are associated with tumor regression and seem to be infrequent and/or inconsequential during progressive tumor growth.

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.

Characterization of the presumptive sarcoma cells in primary MSV tumors

Presumptive sarcoma cells have been isolated from primary MSV tumors induced in normal, immunosuppressed (ALG) and athymic nude mice. These cells were atypical in appearance, induced tumors in secondary hosts and expressed the viral antigens gp70, p30 and p12. In vitro growth characteristics of the MSV cells were tested in a variety of assays defining cell transformation. None of these indicated that the virus-positive cells were transformed. Sex chromosome marker studies were carried out to determine if secondary tumor arose solely from proliferation of donor cells or through infection of host tissue. Tumors from female irradiated mice induced by injections of tumor cells derived from male mice contained a high proportion of metaphases of non-donor origin, indicating that infection is an important but not the sole mechanism involved in tumor transfer. These data also demonstrated that many of the sarcoma cells are damaged as a result of infection as shown by the presence of chromosome breaks and aneuploid metaphases. Histologic sections of both regressor and progressor tumors showed that the virus-positive cells were scattered as single cells surrounded by inflammatory cells, rather than as masses of dividing virus-positive cells found in the MSV-induced transplanted tumor. Collectively, these data support the contention that the MSV tumor is the manifestation of a response to a highly noxious virus infection rather than a tumor of dividing, transformed malignant cells.

Mononuclear phagocytes in the human placenta

Hofbauer cells have been identified by morphological criteria in human placentae and are considered to be mononuclear phagocytes. An increasing recognition of the morphological heterogeneity of mononuclear phagocytes and of the considerable difficulty in their recognition in histological sections has suggested that they may be considerably more numerous in the placenta than has been appreciated. The use of specific markers for mononuclear phagocytes in the present study facilitated their identification and quantitation in the placenta. Approximately 65 per cent of the cells in cell suspensions from placentae at all stages of gestation exhibited avid Fc receptors and were morphologically indistinguishable from mononuclear phagocytes. Most of these cells also were phagocytic and expressed C3 receptors. Furthermore, when cells expressing alpha-naphthyl butyrate esterase positivity as well as high-affinity receptors for immune complexes were visualized in the stroma of chorionic villi, nearly all stromal cells were positive. The results suggest that Hofbauer cells represent the fully differentiated, morphologically-obvious end-stage members of a large mononuclear phagocyte population which is present in chorionic villi throughout gestation.

Characterization of lymphocyte subsets in spontaneous mouse mammary tumors and host lymphoid organs

The subsets of small lymphocytes (surface Igm-positive or B, Thy-I-positive or T and "double-negative" or null) appearing within spontaneous mammary tumors of C3H retired breeder female mice and in various lymphoid organs of the host at different stages of tumor development were characterized directly using a radioautographic method. Tumor-bearing mice showed early transient splenomegaly and progressive atrophy of the thymus. The proportion of T small lymphocytes increased with tumor age within the tumor and in the spleen, blood and thymus; then, except in the spleen, these proportions declined again by 8 weeks of tumor growth. The incidence of B small lymphocytes showed no change in the tumor or thymus; there was an increase in the blood after 3 weeks, and a small decrease in the spleen after 7 weeks. At all the sites examined, the proportion of null small lymphocytes declined from an initial high level observed in the elderly tumor-free control mice, and then recovered to control levels after 7 weeks. The absolute numbers of T and null cells in the spleen changed in parallel to their proportions, while splenic B-cell numbers increased at 1-3 weeks. In the thymus the absolute numbers of all subsets decreased, with a late recovery of null cell numbers. Age-matched control mice showed higher proportions of null cells in the spleen, blood and thymus, and lower proportions of T cells in the blood and spleen, than did young normal mice. This spontaneous tumor appears to be characterized by an increase in T cells, rather than in null cells, as observed for rapidly growing transplanted tumors. The null cell rise in the present case takes place before the clinical appearance of tumors. In both cases, however, tumor-infiltrating B cells exhibited low levels of surface Ig, possibly related to a low level of maturation. The functional significance of these findings remains to be determined.

Human monocyte antibody-dependent cell-mediated cytotoxicity to tumor cells

Previous investigations of mononuclear cell antibody-dependent cell-mediated cytotoxicity (ADCC) toward tumor cells suggest that K lymphocytes and not monocytes are active in this cytotoxic reaction. This report, however, demonstrates that human monocytes are able to carry out ADCC toward three different human tumor cell lines (CEM T lymphoblasts, Raji bone marrow-derived (B) lymphoblasts, and HeLa cells). The cytolytic event was found to be temperature dependent and rapid, with most of the lysis occurring in the first 4 h of incubation. The extent of lysis was directly related to the number of monocytes (effector cells) and to the degree of antibody sensitization of the target cells. The antibody-dependent cell contact-mediated nature of the cytolytic event was confirmed by inhibition with competing nonspecific monomeric immunoglobulin and by the ability of monocytes in "innocent bystander" experiments to lyse antibody-coated targets but not nonantibody-coated target cells. Evidence that monocytes were clearly the effector cells in the monocyte preparations included the observation that preincubation of effector cells with opsonized zymosan particles abolished ADCC by monocytes, but had little effect on lymphocyte ADCC. Furthermore, no evidence for Fc receptor K lymphocyte contamination of the monocyte preparations was found using antibody-coated target cells that were selectively lysed by lymphocytes but not monocytes. We suggest that ADCC toward tumor cell targets may prove to be a useful assay of monocyte function in normal and disease states.