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W Den Otter

Publications and source records attributed to W Den Otter.

At least 109 records · Page 6Linked to original sources

Differences in the induction of macrophage cytotoxicity by the specific T lymphocyte factor, specific macrophage arming factor (SMAF), and the lymphokine, macrophage activating factor (MAF).

Specific T cell factors, such as specific macrophage arming factor (SMAF), are involved in the initiation of the immune response. Induction of SMAF-producing T lymphocytes in vivo and of SMAF production by T lymphocytes in vitro is dependent on the presence of intact tumor cells, and is independent of antigen presentation by macrophages. SMAF renders peritoneal macrophages cytotoxic for tumor cells. The armed peritoneal macrophages expressed a specific cytotoxicity. However, antigen-presenting cells can trigger lymphokine-producing T lymphocytes. These T lymphocytes produce lymphokines (e.g. macrophage activating factor (MAF] that activate macrophages. The MAF-activated macrophages express a non-specific tumoricidal activity. In the present study, we investigated the difference in the induction of macrophage cytotoxicity by SMAF and MAF. The following differences were found: 1) SMAF renders peritoneal resident macrophages cytotoxic, whereas MAF could only render peritoneal exudate macrophages cytotoxic. 2) SMAF requires only a 4-h incubation with macrophages, whereas MAF activates macrophages optimally after 12 h. 3) SMAF-armed macrophages recognize only the specific target cell(s), and thus, the cytotoxicity is specific in its expression. MAF activated macrophages were non-specifically cytotoxic. 4) Lipopolysaccharide (LPS) in the culture medium did not enhance the cytotoxicity of SMAF-armed macrophages. In contrast, MAF induced tumoricidal activity was enhanced by adding LPS to the culture medium. 5) After adsorption chromatography with anti-murine interferon-gamma (IFN-gamma), the arming capacity of SMAF supernatant was not reduced, whereas the activating capacity of the MAF supernatant was significantly reduced or abrogated. After immunization of mice with allogeneic tumor cells, SMAF-producing lymphocytes were detected in the draining lymph nodes already 4 days after immunization and up to 12 days. Lymphocytes with the capacity to produce MAF were present in the draining lymph nodes 14-24 days after immunization. Our data indicate that the T cell factors SMAF and MAF can both render macrophages cytotoxic, but act in a different way and during different stages of the cellular immune response against allogeneic tumor cells.

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Non-ocular cancer in patients with hereditary retinoblastoma and their relatives.

In The Netherlands, retinoblastoma patients have been registered in the Utrecht national retinoblastoma registry since 1862. This register is virtually complete from 1945 onwards. We describe a unique epidemiological survey of the occurrence of non-ocular cancer in all patients registered during the period 1945-1970. The occurrence of non-ocular cancer in relatives of patients with hereditary retinoblastoma is also reported. One hundred and forty-one patients with hereditary retinoblastoma were studied for non-ocular second primary cancer. Nineteen patients died of retinoblastoma. The median follow-up of the surviving 122 patients was 25 years. Seventeen of these patients developed a second primary cancer, most frequently soft-tissue sarcoma. The cumulative incidence of non-ocular cancer was 19% at the age of 35, i.e., a 14-fold increase as compared to the general population. Twelve patients with hereditary retinoblastoma died of non-ocular cancer whereas none of 252 patients with non-hereditary retinoblastoma died of non-ocular cancer. Furthermore, among the parents of our hereditary retinoblastoma patients, 24 (born before 1945) had also been affected by retinoblastoma or had affected sibs. In the parents, 4 tumors occurred, of which 2 were rhabdomyosarcomas and 2 were urinary bladder cancers. Both types of non-ocular cancer were also encountered among the 122 patients with hereditary retinoblastoma. In 103 fathers and 103 mothers of patients with hereditary retinoblastoma who did not have retinoblastoma themselves, there was no previous family history of retinoblastoma. The fathers had a relative risk of 8.3 for pancreatic cancer compared to the general population. There was no significant increase in the number of non-ocular tumors in 332 sibs of patients with hereditary retinoblastoma.

Adolescent↗

Macrophage infiltration in tumors and tumor-surrounding tissue: influence of serotonin and sensitized lymphocytes.

In a delayed-type hypersensitivity reaction serotonin released from mast cells plays an important role in the induction of a cellular infiltrate at the site of antigen challenge. In analogy, we have studied whether it is possible to enhance the number of intratumoral macrophages by injecting serotonin into a s.c. SL2 lymphosarcoma. The vessels in the tissue surrounding the tumor responded well to serotonin, as there was an influx of i.v. injected 51Cr-labeled sensitized spleen cells in this tissue during the first 4 h after intratumoral injection of serotonin. At 24 h after serotonin injection there was an influx of macrophages into this tumor-surrounding tissue. No influx of cells was detected in the tumor itself during the first hours after injection of serotonin. In the tumor, similar phenomena occurred as in the surrounding tissue, but with a delay of about 24 h. This suggests that lymphocytes leave the blood circulation in the tumor-surrounding tissue and migrate to the tumor. The influx of macrophages into the tumor after intratumoral injection of serotonin is probably due to an immunological reaction as the lymphocyte influx preceeds the macrophage influx into tumors. In addition, transfer of sensitized lymphocytes, as well as lymphocytes from a tumor-bearing host caused an enhanced influx of macrophages into the tumor. To test the specificity and serotonin dependency of the phenomenon of infiltrating cells in tumors we have used a footpad swelling assay in which the serotonin dependency and the antigen specificity of the response against syngeneic tumor cells was shown. The following picture emerged: an intratumoral serotonin injection enables lymphocytes to leave blood vessels in the tumor-surrounding tissue. These lymphocytes with specificity for tumor antigens migrate to the tumor. After contact with the antigenic tumor cells, these lymphocytes secrete chemoattractive factors for monocytes/macrophages. Also these monocytes/macrophages leave the circulation in the tumor-surrounding tissue. Subsequently the macrophages invade the tumor. We conclude that the number of intratumoral macrophages can be enhanced by serotonin.

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Immune reactivity in SL2 lymphoma-bearing mice compared with SL2-immunized mice.

We have studied the rather paradoxical phenomenon of the growth of an antigenic tumor in an immunocomponent host. This phenomenon was studied by comparing the lymphocyte reactivity and the macrophage cytotoxicity, during SL2 growth in DBA/2 mice (SL2-bearing mice) and in DBA/2 mice immunized against SL2 tumor cells (SL2-immune mice). Immune mice rejected a challenge of tumor cells. The immune T-lymphocytes rendered macrophages cytotoxic (arming) and were able to transfer tumor resistance to naive animals. Nonimmunized mice did not reject a challenge of SL2 cells. In these tumor-bearing mice various forms of immune reactivity were tested. Lymphocytes with the capacity to arm macrophages could not be found in the lymphoid organs. However, lymphocytes isolated from the tissue directly surrounding the subcutaneous SL2 tumor could arm macrophages in vitro. Shortly after subcutaneous tumor grafting cytotoxic macrophages were found in the peritoneal cavity. In the serum macrophage arming factors were detected that rendered macrophages cytotoxic in vitro. This cytotoxicity of the peritoneal macrophages and the presence of macrophage arming factors in the serum showed a similar biphasic pattern. The first phase of cytotoxicity between day 3 and 8 after tumor grafting was tumor (SL2) specific. The second phase from day 12 and onwards was not tumor specific. During the first 4 days after SL2 grafting the DBA/2 mice expressed a specific concomitant immunity to a second tumor graft. Then 7 or more days after grafting the first SL2 tumor, the concomitant immunity was nonspecific as the growth of a second SL2 tumor graft and a L5178Y (DBA/2) tumor graft were inhibited. In addition, the immune suppressive activity of serum and lymphocytes was tested. Neither serum nor lymphocytes from SL2-bearing mice suppressed the macrophage arming capacity of SL2 immune lymphocytes. Lymphocytes from tumor-bearing mice did not inhibit the capacity of SL2-immune lymphocytes to transfer resistance to naive animals. On the contrary, lymphocytes obtained from SL2-bearing mice 14 days after SL2 grafting transfered tumor resistance in a Winn-type assay. These data suggest that the growth of an antigenic tumor is due to the inability of the immune system to mount an effective antitumor effector cell population during tumor growth, rather than an immune suppression of the antitumor reactivity, as a limited immune reactivity could be detected in tumor-bearing mice, whereas immune suppression could not be detected.

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Spontaneous tumor rejection is not always due to a complete cellular rejection.

In this paper we have studied whether there is a correlation between efficacy of hosts to reject tumor cells spontaneously and the induction of cytotoxic macrophages in these recipients due to injection (immunization) with tumor cells. Results show that there is no cause-effect relationship between macrophage cytotoxicity and tumor rejection in vivo. This lack of cause-effect relationship is greatly influenced by differences in immunogenicity between the various tumor cell lines as well as by the release of tumor-factors by some of these tumors.

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Non-ocular cancer in hereditary retinoblastoma survivors and relatives.

An epidemiological survey has been carried out to establish the incidence of second malignant neoplasms in hereditary retinoblastoma survivors in The Netherlands and the relative risk of cancer in non-affected relatives. The cumulative incidence of second neoplasms was 19% at the age of 35 years. Fathers, unaffected by retinoblastoma, were at risk for pancreatic cancer, the relative risk being 8.3.

Eye Neoplasms↗

The absence of delayed-type hypersensitivity reactivity in a syngeneic murine tumour system.

In different murine systems, delayed-type hypersensitivity (DTH) swelling responses at 24-48 hr after antigen challenge were preceded by an early 2-hr swelling response. The 24-hr DTH response is thought to depend on this early (DTH-initiating) hypersensitivity response. In this paper we show that in the syngeneic DBA/2-SL2 murine tumour system only an early 2-hr swelling response can be evoked. This early hypersensitivity response was tumour specific and serotonin dependent. The early hypersensitivity response in contact hypersensitivity has been ascribed to antigen-specific T-cell factors. To test whether similar T-cell factors were involved in the early hypersensitivity response in this syngeneic tumour system, we have transferred lymph node, spleen lymphocytes and serum from immunized mice into naive recipients. The serum was fractionated in two fractions, a 50,000-80,000 MW fraction, and a 120,000-190,000 MW fraction. In recipients of lymphocytes, total serum and the 50,000-80,000 MW fraction of the serum, an early hypersensitivity response can be evoked. So, these data suggest the involvement of specific T-cell factors in the development of an early hypersensitivity response against syngeneic tumour cells. Despite the development of an early (DTH initiating) hypersensitivity swelling response these immunized animals cannot develop a classical 24-hr swelling response. This absence of the 24-hr response in the presence of the 2-hr response is discussed in relation to the frequently observed immune suppression in tumour-bearing mice.

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Contrasting in vitro effects of retinol and mononuclear cell factor on young and old human cartilage.

Studies with young animal cartilage have shown that retinol and mononuclear cell-factor (MCF) cause in vitro breakdown of the cartilage, mediated by the living chondrocyte (indirect degradation). We studied the effects of retinol and MCF on healthy human articular cartilage of different ages, measuring the effects on proteoglycan (PG) content of the cartilage, and on PG synthesis during 8 days of culture. This study shows: Retinol and MCF induce indirect degradation of young, but not of old human cartilage of the humeral head; Both retinol and MCF suppress PG synthesis of young and stimulate PG synthesis of old cartilage; The effects of retinol and MCF on cartilage PG content and on PG synthesis are related to the metabolic state of the chondrocyte; Therefore mononuclear cell-factor may have a destructive or beneficial effect on cartilage depending on whether proteoglycan synthesizing activity is high or low, respectively.

Adolescent↗

Specific tumoricidal activity of cytotoxic macrophages and cytotoxic lymphocytes.

The antitumor potency and specificity of syngeneic immune peritoneal exudate cells were tested. Groups of DBA/2 mice were immunized against syngeneic SL2 tumor cells. Then 6 days after the last immunization the antitumor potency, and the specificity of the immunization reaction was tested by injecting groups of the immunized mice with 10(3) to 5 X 10(7) DBA/2 derived L1210, L5178Y, P815 or SL2 tumor cells, and injecting immune peritoneal exudate cells into DBA/2 mice which had been injected 2 h earlier i.p. with 2 X 10(4) or 2 X 10(5) L1210, L5178Y, P815, or SL2 cells. Furthermore the tumor specific cytotoxicity in vitro of isolated immune (vs SL2) peritoneal macrophages was tested against L1210, L5178Y, P815, and SL2 cells. The "reciprocal" experiments (previous immunization against L1210, L5178Y, or P815 cells and 'challenge' with SL2) were also done. Finally, we tested the tumor-specific cytotoxicity of isolated immune peritoneal T-lymphocytes. It was shown that the rejection of tumor cells in previously immunized mice, the antitumor efficacy of the transferred immune peritoneal exudate cells and the in vitro cytotoxicity of purified immune peritoneal macrophages and lymphocytes, were tumor-specific reactions. That is only between the SL2 and L5178Y tumors were cross-reactions observed. However, this cross-reaction was not found at the level of cytotoxic T-cells. This suggests that cytotoxic T-cells and cytotoxic macrophages probably have different mechanisms of recognition of the specific tumor target cells. Treatment of macrophage monolayers, prepared from macrophages of immunized mice, with monoclonal anti-Thy-1 antibodies plus complement caused no decrease in cytotoxicity. This shows that macrophages can really express specific cytotoxicity. Tumoricidal macrophages probably obtain their tumor specificity through the activities of tumor-specific factors produced by sensitized T-cells.

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The role of host lymphocytes and host macrophages in antitumor reactions after injection of sensitized lymphocytes and tumor target cells into naive mice.

DBA/2 mice were immunized i.p. against syngeneic SL2 lymphosarcoma cells. At various days after the last immunization peritoneal and spleen lymphocytes were collected. The lymphocyte suspensions were enriched for T-cells by nylon wool filtration. The peritoneal T-cells from immunized mice (a) expressed direct specific antitumor cytotoxicity in vitro, (b) induced macrophage cytotoxicity in vitro, and (c) exerted tumor neutralization measured in a Winn-type assay. Spleen T-cells from these immunized mice (a) expressed no direct specific antitumor cytotoxicity in vitro, (b) only induced moderate macrophage cytotoxicity in vitro, but (c) exerted tumor neutralization in a Winn assay. For effective tumor neutralization in vivo effector target cell ratios of 1000:1 were required. When the effector/target ratio of 1000:1 was maintained but the absolute numbers of effector and target cells were lowered from 10(6) to 10(5) lymphocytes and 10(3) to 10(2) target cells respectively, no tumor neutralization was obtained. The major effect of the sensitized-transferred T-lymphocytes seemed to be the induction of cytotoxic macrophages in the (naive) recipient mice, as the peritoneal macrophages collected from the recipient mice 7 days after i.p. injection of a mixture of sensitized T-cells and tumor cells were cytotoxic. Purified peritoneal T-lymphocytes collected from these recipient mice were able to induce macrophage cytotoxicity in vitro but expressed no cytotoxic T-cell activity. In conclusion, our results show that in the tumor system used, tumor neutralization after transfer of sensitized lymphocytes is not dependent on the presence of cytotoxic T-lymphocytes. Lymphocytes with the strongest potency to render macrophages cytotoxic (in vitro and in vivo) also induce the best tumor neutralization in vivo, suggesting an important role for host macrophages as antitumor effector cells.

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Immune surveillance and natural resistance: an evaluation.

Concepts in tumour immunology are changing fundamentally. Around 1970 tumour immunology contained the following related concepts: Thousands of tumour cells arise de novo each day. Tumour cells are antigenic in their host. All these antigenic tumour cells are killed by a strong immune surveillance system. A more likely set of concepts looks as follows: Tumour cells do not arise frequently. Tumour cells may be antigenic or not. There is no need to postulate a very strong immune surveillance or natural resistance system. In this paper I am reviewing our present knowledge of immune surveillance and natural resistance. Only scanty information appears to be available. This information suggests that virally induced tumours are usually killed by cytotoxic T lymphocytes, and natural killer cells, whereas immune surveillance and natural resistance against other tumours may be quite weak.

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A survey of some formal models in tumor immunology.

Computer technology has acquired an important role in structuring a variety of biological systems. The availability of modern powerful computers has stimulated the development of good and accurate models of biological systems. Biological systems, such as the immune response against cancer, are complex and it is difficult to experimentally control all the interacting elements constituting the immune response of a host to cancer. Complex biosystems do not always behave or act as expected during experimental investigation. In these cases computer models can be helpful in understanding the behavior of such complex systems. The purpose of this review is to consider the use of mathematical models to study the immune response against cancer. The logic and design of some operable models relevant for tumor immunology will be discussed. Special attention is given to the conceptualization of a model based upon a new hypothesis of tumor rejection presented by De Weger et al. [10]. Technical details concerning the mathematical aspects, differential equations, details on hardware and software package etc. are not included in this survey. These details are contained to in the original papers.

Computer Simulation↗

Higher ADCC of murine peritoneal cells after immunization with allogenic tumor cells as compared with stimulation by adriamycin, BCG, and thioglycolate.

Normal peritoneal cells or spleen cells from C57BL mice could not lyse SRBC in an ADCC assay. After intraperitoneal injection of Adriamycin, BCG or thioglycolate the ADCC of peritoneal cells toward antibody-coated SRBC was elevated to 30% in contrast to the ADCC of spleen cells. However, peritoneal cells but not spleen cells of mice immunized with allogenic tumor cells (DBA SL2) showed ADCC levels at least two times higher than the levels observed after stimulation by other agents. Maximal ADCC levels (55.8%) were observed 10 to 15 days after immunization. Direct cytotoxicity towards SRBC increased to a maximum of 17.7% at 9 days after immunization. The effector cells in this system are thought to be macrophages, for ADCC activity was only present in the plastic-adherent cell fraction. Cell to cell contact was necessary for ADCC to occur; nonsensitized erythrocytes were not lysed when added to a mixture of effector cells and sensitized erythrocytes. Concentrations of antibody of 1 pg/ml were sufficient to induce ADCC, and effector cell to target cell ratios could be as low as 0.05. The finding that macrophages of mice immunized with allogenic tumor cells exhibit higher ADCC levels than macrophages elicited in other ways can contribute to the investigation of combined cancer therapy with antibodies and biological response modifiers.

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