Antibody-dependent Macrophage-mediated Cytotoxicity Research Articles

IgE re-programs alternatively-activated human macrophages towards pro-inflammatory anti-tumoural states.

BackgroundAntibody Fc-driven engagement of macrophages is critical for evoking cellular activation and effector functions and influencing tumour-associated macrophage (TAM) recruitment. We previously reported that IgE class antibodies promote restriction of cancer growth in rodent models associated with significant TAM infiltration. However, the human macrophage-associated IgE-Fc Receptor (FcεR) axis remains unexplored. We investigated the effects of anti-tumour IgE stimulation on human macrophage activation.MethodsHuman blood monocyte-differentiated quiescent (M0), classically-(M1) and alternatively-(M2) activated macrophages were crosslinked with IgE and polyclonal antibodies to mimic immune complex formation. We examined surface marker expression, cytokine secretion, protein kinase phosphorylation and gene expression in IgE-stimulated macrophages and IgE antibody-dependent macrophage-mediated cytotoxicity (ADCC) against tumour cells.FindingsA proportion (40%) of M2 and (<20%) M0 and M1 macrophages expressed the high-affinity IgE receptor FcεRI. IgE crosslinking triggered upregulation of co-stimulatory CD80, increased TNFα, IFNγ, IL-1β, IL-12, IL-10, IL-13, CXCL9, CXCL11 and RANTES secretion by M0 and M2 and additionally enhanced MCP-1 by M2 macrophages. IgE-stimulated M1 macrophages retained secretion of pro-inflammatory cytokines. IgE crosslinking enhanced the FcεRI-dependent signalling pathway, including phosphorylation of the Lyn kinase, ERK1/2 and p38 in M2 macrophages and upregulated Lyn gene expression by M1 and M2 macrophages. Anti-tumour IgE engendered ADCC of cancer cells by all macrophage subsets.InterpretationIgE can engage and re-educate alternatively-activated macrophages towards pro-inflammatory phenotypes and prime all subsets to mediate anti-tumour functions. This points to IgE-mediated cascades with potential to activate immune stroma and may be significant in the clinical development of strategies targeting tumour-resident macrophages.

Therapeutic potential of chimeric anti-(ganglioside GD3) antibody KM871: antitumor activity in xenograft model of melanoma and effector function analysis.

KM871 is a chimeric antibody recognizing ganglioside GD3, which is one of the major gangliosides expressed on the cell surface of human tumors of neuroectodermal origin. This study demonstrates the antitumor activity of KM871 against human melanoma xenografts in nude mice, and analyzes the effector function operating in mice. In a well-established tumor model, KM871 showed antitumor activity against H-15 and SK-MEL-28 human melanoma but not against H-187 and G361 human melanoma when administered intravenously 5 days/week for 2 weeks. The G361 tumor became sensitive when KM871 was first administered on the day of tumor inoculation. In this assay, it was observed that almost all the mice were tumor-free, but a few mice developed tumors. Therefore, we examined the amount and expression pattern of GD3 antigen on G361 tumors escaping from KM871 treatment, but no change was observed. Next we examined the optimal administration schedule for KM871 in mice, using H-15 melanoma. KM871 showed antitumor activity when administered intravenously either 5 days/week for 2 weeks or three biweekly doses. However, the effect of the former schedule was stronger than three biweekly doses. To compare the effector function in humans and mice, we studied the complement-mediated cytotoxicity, antibody-dependent cell-mediated cytotoxicity and antibody-dependent macrophage-mediated cytotoxicity of KM871 using complement or effector cells prepared from humans and mice. It was found that the antibody-dependent cell-mediated cytotoxicity exerted by polymorphonuclear cells and antibody-dependent macrophage-mediated cytotoxicity were the only antitumor mechanism of KM871 in mice. However their action was very weak compared with that in humans, and complement-mediated cytotoxicity, which was strong in humans, was not observed in mice. Therefore, the antitumor activity of KM871 against human melanomas evaluated by the nude mouse model might be underestimated. These results indicate that KM871 shows good antitumor activity against GD3-positive human melanoma and the antitumor activity expected in humans might be superior to that of the nude mouse model.

M-CSF gene transduction in multidrug-resistant human cancer cells to enhance anti-P-glycoprotein antibody-dependent macrophage-mediated cytotoxicity.

A human macrophage-colony-stimulating-factor (M-CSF) gene inserted into an expression vector (pRc/CMV-MCSF) was transfected into multidrug-resistant (MDR) human ovarian cancer cells (AD10) to induce secretion of human M-CSF into the medium. The M-CSF level in the culture medium of the transfected cells reached 100 ng/ml after 7 days, and the ability of the cells to secrete M-CSF was stable for at least 3 months. Transfection of the M-CSF gene did not result in any change in expression of MDRI (P-glycoprotein), proliferation or chemosensitivity of the cells from those of the parent cells. There was also no difference between the transfected and the parent cells in susceptibility to NK cell- or interleukin-2-activated killer-cell-mediated cytotoxicity. Human blood monocytes that had been incubated for 4 days in medium with the culture supernatant of MH-AD10 cells exhibited higher ADCC activity than untreated monocytes against MDRI-positive cancer cells. This effect of the supernatant of AD10 cells was completely abolished by its treatment with a monoclonal anti-M-CSF antibody (MAb). When transfected human MDR cells were injected into nude mice, an inverse correlation was seen between the ability of the cells to produce M-CSF and their tumorigenicity. Thus, gene modification of MDR cancer cells seems hopeful as a therapeutic method for enhancing anti-MDRI-MAb-dependent macrophage-mediated cytotoxicity against human MDR cancer cells.

Antibody Production Useful for Cytotoxicity against Mouse MM2 Tumor Cells by Peritoneal Macrophages

We applied an antibody-dependent macrophage-mediated cytotoxicity (ADMC) test in order to analyze the effector mechanism of the host-mediated antitumor effects induced by OK-432. Adherent peritoneal exudate (PE) cells were obtained from each of high (C3H/He) and low (B10) responder mice treated with OK-432, and 51Cr-labeled MM2 tumor cells were used as target cells. The cytotoxic activity in vitro coincided well with the results obtained in in vivo antitumor experiments. When adherent PE cells from C3H/He mice reacted with anti-MM2 serum from B10 mice, the degree of ADMC was significantly lower than that obtained with the anti-MM2 serum from C3H/He mice. The removal of IgG1 from the anti-MM2 serum induced in B10 mice resulted in the enhancement of ADMC activity. Then mean level of IgG2 in each of anti-MM2 sera from C3H/He and B10 mice was higher than in normal serum, and the IgG1 level in the antiserum from B10 mice was also higher than that in the serum from normal B10 mice. The present work suggested that the active component(s) in anti-MM2 serum participating in ADMC was a specific antibody of the IgG2 subclass, and that the inhibiting factor(s) was the IgG1 subclass.

Mouse monoclonal antibodies for experimental immunotherapy promotes killing of tumor cells.

Monoclonal antibodies (MAbs) produced against a human colon adenocarcinoma cell line, Colo-205, were tested in antibody-dependent macrophage-mediated cytotoxicity (ADMMC) assays. The antibodies C163, C215, C245 (IgG2a isotype); C151, C239, C241, C242 (IgG1); C152 (IgG2b); and C50 (IgM) were evaluated for their ability to promote killing of Colo-205 cells by thioglycollate-elicited peritoneal mouse macrophages. The concentrations of antibodies tested in ADMMC assays ranged from 1.0 ng/ml to 100 micrograms/ml, and the concentration at which 50% of tumor cells were lysed was used to characterize each antibody. Antibodies of the IgG2a isotype promoted the strongest macrophage-mediated tumor cell lysis effects in vitro. MAbs C215, C163, and C245 were also tested in nude mice which had been inoculated with Colo-205 cells. Tumor suppression was observed in mice injected with MAbs, supporting our ADMMC findings in vitro. Animals treated with MAbs had fewer and smaller tumors, and longer periods of latency between the inoculation of tumor cells and development of tumors, compared to mice sham-treated with PBS. However, in a study of established tumors, C215 antibody did not suppress tumor growth. Serum collected from MAb-treated mice promoted lysis of Colo-205 cells in ADMMC assays while serum from sham-treated mice did not.

Analysis of B. malayi microfilarial antigens by immunoblotting.

BALB/C mice were immunized with heavy or low infection of live B. malayi microfilariae or immunised with different fractions of the microfilarial antigens. Antibody levels and antibody dependent macrophage mediated cytotoxicity to B. malayi microfilariae were determined in the immunized sera. Antigens responsible for induction of antibodies were recognised in B. malayi microfilarial extract by immunoblotting. Appearance of cytotoxic antibodies correlates with recognition of certain common antigens in microfilarial extract such as 45, 54, 62, 66 and 76 KDa mol. wt. proteins.

Immunoprotective behaviour of plasma-membrane-associated antigens of axenic Entamoeba histolytica

Immunisation of golden hamsters with plasma-membrane-associated antigens of a virulent subline of axenic Entamoeba histolytica strain NIH 200 V, entrapped in multilamellar phosphatidylcholine liposomes (MPL) or Freund's complete adjuvant (FCA), afforded protection against intrahepatic challenge with axenic amoebic trophozoites of the same strain. Amoebic liver abscess developed in 86% and 80% of the animals that received empty liposomes or buffer emulsified in FCA but in none of the animals that received plasma-membrane-antigen vaccines. All the immunised animals had significantly higher levels (p less than 0.001) of antibodies to plasma-membrane components and significantly higher levels (p less than 0.001) of cellular sensitisation. Antibody-dependent macrophage-mediated cytotoxicity against trophozoites was also found to be significantly greater (p less than 0.001) in immunised animals. Liposome-entrapped antigens stimulated the immune system of the host as well as, or better than, antigens administered with FCA.

Cytophilic anti-thyroglobulin antibody and antibody-dependent macrophage-mediated cytotoxicity in Hashimoto's thyroiditis.

Antibody-dependent macrophage-mediated cytotoxicity was studied to determine the significance of cytophilic anti-thyroglobulin antibody (ATgA) present in the sera of patients with Hashimoto's thyroiditis. Effector cells were normal human monocytes or guinea-pig peritoneal exudate cells, and target cells were human thyroglobulin(Tg)-coated chicken erythrocytes. Cytotoxicity was evaluated by morphological observation and by 51Cr-releasing assay. Normal human monocytes rapidly destroyed ATgA-bound Tg-coated chicken erythrocytes by extracellular cytolysis and by phagocytosis. On the contrary, human monocytes "armed" with cytophilic ATgA destroyed Tg-coated chicken erythrocytes slowly and to a lesser extent, and only by extracellular cytolysis. When normal monocytes or peritoneal exudate cells were incubated with Tg-coated chicken erythrocytes in the presence of the sera of patients with Hashimoto's thyroiditis, phagocytosis occurred rapidly, but extracellular cytolysis developed rather slowly. These data suggest the possibility that human monocytes participate in antibody-dependent cell-mediated cytotoxicity (ADCC) in vivo, which may be an important destructive mechanism in Hashimoto's thyroiditis. It is also possible that ATgA cytophilic for monocytes render non-immune peripheral monocytes cytotoxic against Tg-bearing cells.

Antibody-dependent macrophage-mediated cytotoxicity against Entamoeba histolytica.

Interactions between trophozoites of Entamoeba histolytica and peritoneal exudate macrophages from unsensitised and antigen-sensitised animals were studied in vitro. Normal macrophages killed trophozoites to some extent. This killing capacity was enhanced by prior sensitisation of the animals with specific antigen. Incorporation of anti-amoebic antiserum in the amoeba-macrophage mixture greatly enhanced the killing capacity of macrophages. Fraction one (F-I) of a crude amoebic extract was most effective in enhancing the cytotoxicity of macrophages by prior sensitisation and anti-F-I serum was the most effective antiserum. The cytotoxicity-inducing capacity of the immune serum resided in the IgG but not in the IgM fraction.

Inhibition of human tumor growth by IgG2A monoclonal antibodies correlates with antibody density on tumor cells.

Eight monoclonal antibodies (MAb) of IgG2a isotype that were produced against human melanomas were tested for tumor growth-inhibiting properties in nude mice injected with human melanoma cells of various origins. Four of the eight MAb inhibited growth of these tumors, and all four of these antibodies reacted in antibody-dependent macrophage-mediated cytotoxicity (ADMC) assays in vitro. The MAb that were inactive in vivo also did not react in these assays in vitro. The number of antibody-binding sites per cell on the tumor cell surface was significantly higher for tumoricidal MAb as compared to unreactive MAb. On the other hand, the percentage of tumor cells binding the MAb and the binding affinity to these cells were the same for the two groups of MAb. Also, tumoricidal and nontumoricidal MAb bound with similar affinity and antibody density to Fc receptors on macrophages. The importance of the number of antibody sites on the tumor cell surface for tumor destruction by MAb was confirmed by the demonstration of tumoricidal effects of mixtures of MAb that were by themselves not tumoricidal. MAb binding to different molecules on melanoma cells were complementary in ADMC, whereas MAb directed to the same molecule but to different epitopes were not.

Stimulation of monoclonal antibody-dependent macrophage-mediated cytotoxicity against human tumors by lentinan

Stimulation of monoclonal antibody-dependent macrophage-mediated cytotoxicity against human tumors by lentinan

Efficient selection of human tumor growth-inhibiting monoclonal antibodies

A method is described for selection early after fusion for hybridomas that secrete IgG2a monoclonal antibodies (MAbs) with binding specificity for antigens on the human tumor cells used to immunize mice. By combining this preselection method with antibody-dependent macrophage-mediated cytotoxicity assays, it was possible to select those MAbs mediating a tumoricidal effect against tumor cells in culture and inhibiting the growth of tumor xenografts in nude mice. Two such MAbs, GA733 and CO441, inhibited the growth of colorectal carcinoma cells, and one of them (GA733) was effective even when administered 6 days after implantation of tumor cells. These results suggest the potential usefulness of the 2 MAbs in immunodiagnosis and immunotherapy of human tumors.

Proliferation of human malignant hematopoietic cells in immunodeficient mice: suppression by antibody to pluripotent K-562 leukemia cells involves direct cytolysis and effector cells

Six human hematopoetic cell lines were successfully heterotransplanted into athymic (nude) and asplenic-athymic (lasat) neonatal mice. The tumors arising from leukemia and lymphoma cells could then be serially transplanted into adult nude mice. Seven days after the fourth serial mouse passage, each mouse was treated with goat immune gamma globulin against K-562 cells. One control group was treated similarly, but with nonimmune (normal) gamma globulin, while another control group was not treated. The goat gamma globulin was not toxic for nude and lasat mice, and the immune, but not the normal, gamma globulin suppressed local subcutaneous growth of myelosarcomas, lymphosarcomas, and Burkitt lymphoma cells. On the other hand, the growth of lung, breast, and prostatic carcinomas and a melanoma of human origin were not altered by the immune gamma globulin. Since suppression of cell growth occurred equally well in decomplemented mice, a complement-mediated cytotoxicity apparently cannot be considered as responsible for the abrogation. The Fab fragment of the immunoglobulin did not suppress the growth of the myelosarcomas. We conclude that antibody suppression of the in vivo proliferation was specific for malignant hematopoietic cells and that the Fc portion of IgG is necessary for in vivo cytolysis of leukemia cells. The most probable mechanisms are direct antibody cytolysis and antibody-dependent macrophage-mediated cytotoxicity.

Proliferation of Human Malignant Hematopoietic Cells in Immunodeficient Mice: Suppression by Antibody to Pluripotent K-562 Leukemia Cells Involves Direct Cytolysis and Effector Cells

Six human hematopoetic cell lines were successfully heterotransplanted into athymic (nude) and asplenic-athymic (lasat) neonatal mice. The tumors arising from leukemia and lymphoma cells could then be serially transplanted into adult nude mice. Seven days after the fourth serial mouse passage, each mouse was treated with goat immune gamma globulin against K-562 cells. One control group was treated similarly, but with nonimmune (normal) gamma globulin, while another control group was not treated. The goat gamma globulin was not toxic for nude and lasat mice, and the immune, but not the normal, gamma globulin suppressed local subcutaneous growth of myelosarcomas, lymphosarcomas, and Burkitt lymphoma cells. On the other hand, the growth of lung, breast, and prostatic carcinomas and a melanoma of human origin were not altered by the immune gamma globulin. Since suppression of cell growth occurred equally well in decomplemented mice, a complement-mediated cytotoxicity apparently cannot be considered as responsible for the abrogation. The Fab fragment of the immunoglobulin did not suppress the growth of the myelosarcomas. We conclude that antibody suppression of the in vivo proliferation was specific for malignant hematopoietic cells and that the Fc portion of IgG is necessary for in vivo cytolysis of leukemia cells. The most probable mechanisms are direct antibody cytolysis and antibody-dependent macrophage-mediated cytotoxicity.

Activation of macrophages by in vitro allostimulated T cells.

Murine peritoneal macrophages, parabiotically co-cultured with combinations of in vitro H-2 sensitized thymus-derived lymphocytes obtained from drug-pretreated mice, possessed an increased cytotoxicity against alloantibody-coated target cells. This heightened activity appeared to be accentuated by and dependent on T-cell synergy. After 5 days of in vitro allosensitization at 37 degrees C, cortisone-resistant thymocytes allosensitized in combination with cyclophosphamide-pretreated splenic T cells released molecules that produced strong antibody-dependent macrophage-mediated cytotoxicity (ADCC). This enhanced ADCC correlated with increased macrophage rosetting with IgG-sensitized erythrocytes. These heightened activities resulted from soluble mediators released by the activated T cells which diffused across a 0.22-microns Millipore filter and were not dependent on lymphocyte-macrophage contact. Evidence that these molecules originated from the highly enriched T-cell populations and were not synthesized de novo by macrophages was supported by results of pretreatment with protein and RNA synthesis inhibitors. Evidence that soluble Fc receptors released from the alloactivated T cells were responsible for the increased macrophage EA binding and ADCC was obtained in affinity chromatography experiments in which activity could be depleted by passage over a Sepharose-Fc-coupled column and recovered in the column eluate.

Induction of liver cell injury by antibody-dependent monocyte-mediated cytotoxicity in vitro.

The isolated liver cells coated with the anti-liver cell membrane antibody were damaged by incubation with the peripheral blood mononuclear cells. This was demonstrated by measuring the reduction of protein synthesis in the target liver cells. Adherent cells from the peripheral blood mononuclear cells were shown to have a sufficient capacity acting on the isolated liver cells as an effector when they were separated from the peripheral blood of normal and patients with acute or chronic active hepatitis. However, those from patients with liver cirrhosis or hepatoma did not show such effector activity in antibody-dependent cell-mediated liver cell damage. These results suggest that possibly antibody-dependent macrophage-mediated cytotoxicity may play some role in the induction of liver cell injury because the anti-hepatocyte membrane antibody is frequently detected in patient's sera, especially in those with chronic active hepatitis.

IgG2a monoclonal antibodies inhibit human tumor growth through interaction with effector cells.

Monoclonal antibodies of IgG2a isotype specifically inhibited growth of human tumors in nude mice. Twenty-three monoclonal antibodies of other isotypes showed no tumoricidal reactivity. Complement depletion of nude mice had no effect on tumor suppression by monoclonal antibody. The role of T and killer cells as mediators of the monoclonal antibody effect in nude mice was virtually excluded. On the other hand, macrophages were strongly incriminated as effector cells because silica treatment of nude mice abolished the tumoricidal effect of monoclonal antibody. IgG2a monoclonal antibody-dependent macrophage-mediated cytotoxicity assays with human tumor cells in culture resulted in specific lysis of tumor cells.

Cooperative Effects between Lymphokine-induced and Antibody-dependent Macrophage-mediated Cytotoxicity in C57BL/10 and C3H/HeJ Mice

Cooperative effects are described between 2 different mechanisms of macrophage-mediated cytotoxicity, the lymphokine-induced and the antibody-dependent cytotoxicity: Macrophages are activated to nonspecific cytotoxicity by a 24 h incubation with lymphokines. Young macrophages cultured from the bone-marrow or obtained from induced peritoneal exudates, but not the resident peritoneal macrophages, have the capacity to kill antibody-coated tumor cells. To obtain a cooperative effect between the 2 mechanisms both the lymphokine and the antibody have been titrated to a dilution, at which the macrophages did not exert any cytotoxicity. At such subthreshold dosages, however, a very good synergistic effect between the 2 mechanisms was observed. This synergism was obtained with bone-marrow macrophages and with thioglycollate-induced peritoneal macrophages. Macrophages of C3H/HeJ Mice, which have been reported to be a low responder strain for lymphokine activation, showed synergistic effects with similar lymphokine concentrations as macrophages from the high responder strain C57BL/10. Thus, in this synergistic situation the low responsiveness of C3H/HeJ mice is completely compensated. Since during an immune reaction in most cases lymphokine as well as antibody are produced, this synergistic reaction will be of particular relevance for in vivo-situations.

Possible Evidence for Antibody-Dependent Macrophage-Mediated Cytotoxicity Directed against Murine Adenocarcinoma Cells in Vivo

A macrophage-mediated antibody-dependent cellular cytotoxic reaction has been described in a syngeneic murine mammary adenocarcinoma model. The antibody appears to be present in two forms, one apparently complexed with antigen and the other identified as 7S immunoglobulin on Sephadex G-200 and as the IgG2a subclass by blocking of Fc receptors on the macrophages. This antibody is first detected in mice with regressing tumors. Tumor cells from immune mice appear to be coated with this antibody, as they are sensitive to the effects of normal macrophages in vitro, whereas tumor cells from immunologically compromised mice are not. Thus, a macrophage-dependent reaction probably is relevant in the in situ immune defenses against this tumor.