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  1. Article ; Online: Tumor inhibitory T cell immunity may be largely a transplantation artifact not necessarily dependent upon a lack of Tregs.

    Prehn, Richmond T / Prehn, Liisa M

    Theoretical biology & medical modelling

    2013  Volume 10, Page(s) 42

    Abstract: There exists a very large literature suggesting that T cells come in a variety of species and ... that without the action of Tregs tumors would seldom survive inhibition by T cell effectors. We believe that much ... upon the demonstration that that small quantities of effector T cells tend to stimulate tumors while larger quantities ...

    Abstract There exists a very large literature suggesting that T cells come in a variety of species and that without the action of Tregs tumors would seldom survive inhibition by T cell effectors. We believe that much of the evidence supporting the role of Tregs in cancer is compatible with a perhaps simpler hypothesis based upon the demonstration that that small quantities of effector T cells tend to stimulate tumors while larger quantities of seemingly the same cells are inhibitory (an hormesis-like effect). This possibility seems to destroy much of the need to postulate a role for T cell suppressors (Tregs) in cancer, but the exposure of effector T cells to antigen may convert them into Tregs (Tregs do exist). Furthermore, many other data suggest the possibility that immune inhibition of cancer could be a laboratory artifact seldom if ever seen in unmodified nature.
    MeSH term(s) Artifacts ; Cell Proliferation ; Humans ; Immunity/immunology ; Immunization ; Models, Immunological ; Neoplasms/immunology ; Neoplasms/pathology ; T-Lymphocytes, Regulatory/immunology
    Language English
    Publishing date 2013-06-25
    Publishing country England
    Document type Journal Article
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-10-42
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: A new kink in an old theory of carcinogenesis.

    Prehn, Richmond T / Prehn, Liisa M

    Theoretical biology & medical modelling

    2013  Volume 10, Page(s) 12

    Abstract: According to Berenblum's two-stage hypothesis, the first stage in carcinogenesis is the production of benign premalignant lesions. Between this initiation stage and the formation of a malignant tumor there is often a long lag phase. We propose that this ... ...

    Abstract According to Berenblum's two-stage hypothesis, the first stage in carcinogenesis is the production of benign premalignant lesions. Between this initiation stage and the formation of a malignant tumor there is often a long lag phase. We propose that this lag is caused by the delay in the formation of a new and rare tumor-specific antigen, which induces an immune response that stimulates tumor growth. Such tumor-specific antigens could arise as a result of a mutator-like phenotype, which is supposedly present in the benign initial stage of carcinogenesis. According to this hypothesis, the first stage lesion provides a weakly mutagenic environment conducive to the formation of the new antigen(s). If no such new antigens appear so there is no consequent immune response, it is argued that carcinogenesis would seldom if ever ensue.
    MeSH term(s) Cell Transformation, Neoplastic/genetics ; Cell Transformation, Neoplastic/immunology ; Humans ; Models, Theoretical ; Mutation ; Phenotype
    Language English
    Publishing date 2013-02-18
    Publishing country England
    Document type Journal Article
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-10-12
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: The initial immune reaction to a new tumor antigen is always stimulatory and probably necessary for the tumor's growth.

    Prehn, Richmond T

    Clinical & developmental immunology

    2010  Volume 2010

    Abstract: All nascent neoplasms probably elicit at least a weak immune reaction. However, the initial effect of the weak immune reaction on a nascent tumor is always stimulatory rather than inhibitory to tumor growth, assuming only that exposure to the tumor ... ...

    Abstract All nascent neoplasms probably elicit at least a weak immune reaction. However, the initial effect of the weak immune reaction on a nascent tumor is always stimulatory rather than inhibitory to tumor growth, assuming only that exposure to the tumor antigens did not antedate the initiation of the neoplasm (as may occur in some virally induced tumors). This conclusion derives from the observation that the relationship between the magnitude of an adaptive immune reaction and tumor growth is not linear but varies such that while large quantities of antitumor immune reactants tend to inhibit tumor growth, smaller quantities of the same reactants are, for unknown reasons, stimulatory. Any immune reaction must presumably be small before it can become large; hence the initial reaction to the first presentation of a tumor antigen must always be small and in the stimulatory portion of this nonlinear relationship. In mouse-skin carcinogenesis experiments it was found that premalignant papillomas were variously immunogenic, but that the carcinomas that arose in them were, presumably because of induced immune tolerance, nonimmunogenic in the animal of origin.
    MeSH term(s) Adaptive Immunity ; Animals ; Antibody Formation ; Antigen Presentation ; Antigens, Neoplasm/immunology ; Cell Transformation, Neoplastic ; Disease Progression ; Humans ; Immunologic Surveillance ; Mice ; Papilloma/immunology ; Papilloma/pathology ; Skin Neoplasms/immunology ; Skin Neoplasms/pathology
    Chemical Substances Antigens, Neoplasm
    Language English
    Publishing date 2010-07-27
    Publishing country Egypt
    Document type Journal Article ; Review
    ZDB-ID 2119646-1
    ISSN 1740-2530 ; 1740-2522
    ISSN (online) 1740-2530
    ISSN 1740-2522
    DOI 10.1155/2010/851728
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 3137: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
    ab Jg. 2022: Lesesaal (EG)

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  4. Article ; Online: Is an immune reaction required for malignant transformation and cancer growth?

    Prehn, Richmond T / Prehn, Liisa M

    Cancer immunology, immunotherapy : CII

    2012  Volume 61, Issue 7, Page(s) 963–966

    Abstract: Increasing evidence has shown that probably all malignant mouse cells, even those of spontaneous sporadic cancers, are endowed with tumor-specific antigens. Stimulation of cancer growth, rather than inhibition by the immune reaction, is seemingly the ... ...

    Abstract Increasing evidence has shown that probably all malignant mouse cells, even those of spontaneous sporadic cancers, are endowed with tumor-specific antigens. Stimulation of cancer growth, rather than inhibition by the immune reaction, is seemingly the prevalent effect in the animal of origin (the autochthonous animal). Small initial dosages of even strong tumor antigens tend to produce stimulatory immune reactions rather than tumor inhibition in any animal. Thus, an immune response at a low level may be an essential growth-driving feature of nascent cancers, and this may be why all cancers apparently have tumor-specific antigens. Inasmuch as a low level of immunity is stimulatory to tumor growth while larger dosages are inhibitory, immuno-selection via this low response may tend to keep the antitumor immune reaction weak and at a nearly maximal stimulatory level throughout most of a tumor's existence. These facts suggest that both suppression of tumor immunity and a heightened immune reaction might each be therapeutic although very contrasting modalities.
    MeSH term(s) Animals ; Antigens, Neoplasm/immunology ; Cell Growth Processes/immunology ; Cell Transformation, Neoplastic/immunology ; Humans ; Immunologic Surveillance ; Immunotherapy ; Mice ; Neoplasms/immunology ; Neoplasms/pathology
    Chemical Substances Antigens, Neoplasm
    Language English
    Publishing date 2012-05-18
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 195342-4
    ISSN 1432-0851 ; 0340-7004
    ISSN (online) 1432-0851
    ISSN 0340-7004
    DOI 10.1007/s00262-012-1233-5
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 1237: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Article ; Online: Immunostimulation and immunoinhibition of premalignant lesions.

    Prehn, Richmond T

    Theoretical biology & medical modelling

    2007  Volume 4, Page(s) 6

    Abstract: Background: The immune reaction may be either stimulatory or inhibitory to tumor growth, depending upon the local ratio of immune reactants to tumor cells.: Hypothesis: A tumor-stimulatory immune response may be essential for survival of a neoplasm ... ...

    Abstract Background: The immune reaction may be either stimulatory or inhibitory to tumor growth, depending upon the local ratio of immune reactants to tumor cells.
    Hypothesis: A tumor-stimulatory immune response may be essential for survival of a neoplasm in vivo and for the biological progression from a premalignant lesion to a malignancy. Neither a positive nor a negative correlation between the magnitude of an immune-cell infiltrate and a cancer's prognosis can reveal whether the infiltrate was stimulating or inhibiting to the tumor's growth unless the position on the nonlinear curve that relates tumor growth to the magnitude of the immune reaction is known.
    Discussion: This hypothesis is discussed in relation to the development of human malignant melanomas and colorectal cancers.
    MeSH term(s) Animals ; Colorectal Neoplasms/immunology ; Humans ; Immune Tolerance ; Immunization ; Melanoma/immunology ; Mice ; Papilloma/immunology ; Precancerous Conditions/immunology ; Skin Neoplasms/immunology
    Language English
    Publishing date 2007-02-06
    Publishing country England
    Document type Journal Article
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-4-6
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  6. Article ; Online: Cancer immunotherapy by immunosuppression.

    Prehn, Richmond T / Prehn, Liisa M

    Theoretical biology & medical modelling

    2010  Volume 7, Page(s) 45

    Abstract: We have previously suggested that the stimulatory effect of a weak immune reaction on tumor growth may be necessary for the growth of incipient tumors. In the present paper, we enlarge upon and extend that idea by collecting evidence in the literature ... ...

    Abstract We have previously suggested that the stimulatory effect of a weak immune reaction on tumor growth may be necessary for the growth of incipient tumors. In the present paper, we enlarge upon and extend that idea by collecting evidence in the literature bearing upon the new hypothesis that a growing cancer, whether in man or mouse, is throughout its lifespan, probably growing and progressing because of continued immune stimulation by a weak immune reaction. We also suggest that prolonged immunosuppression might interfere with progression and thus be an aid to therapy. While most of the considerable evidence that supports the hypothesis comes from observations of experimental mouse tumors, there is suggestive evidence that human tumors may behave in much the same way, and as far as we can ascertain, there is no present evidence that necessarily refutes the hypothesis.
    MeSH term(s) Animals ; Disease Models, Animal ; Disease Progression ; Humans ; Immune Tolerance/immunology ; Immunosuppression ; Immunotherapy ; Mice ; Models, Immunological ; Neoplasms/immunology ; Neoplasms/pathology ; Neoplasms/therapy
    Language English
    Publishing date 2010-12-15
    Publishing country England
    Document type Journal Article
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-7-45
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Immunologgical self-tolerance in allophenic and embryo-aggregated mice.

    Prehn, Richmond T / Prehn, Liisa M

    Theoretical biology & medical modelling

    2010  Volume 7, Page(s) 38

    Abstract: Allophenic mice, supposedly containing almost equal numbers of cells derived from embryos of mouse strains C57Bl and FVB, were shown in a recent paper to grow the B16 melanoma, a long transplanted tumor of C57Bl origin, much better than did mice of ... ...

    Abstract Allophenic mice, supposedly containing almost equal numbers of cells derived from embryos of mouse strains C57Bl and FVB, were shown in a recent paper to grow the B16 melanoma, a long transplanted tumor of C57Bl origin, much better than did mice of either the parental C57Bl strain or the C57Bl x FVB F1 hybrid. Mice containing smaller proportions of C57Bl cells rejected the tumor. A reconsideration of these suprising data, in light of the current literature, suggests that the better growth of the tumor in the 50-50% allophenics than in the C57Bl parental strain was almost certainly caused by the tumor stimulation engendered by a weak anti-C57Bl immune reaction in the overtly healthy allophenic mice.
    MeSH term(s) Animals ; Cell Aggregation ; Embryo, Mammalian/cytology ; Embryo, Mammalian/immunology ; Mice ; Mice, Inbred Strains ; Models, Immunological ; Nonlinear Dynamics ; Self Tolerance/immunology
    Language English
    Publishing date 2010-09-20
    Publishing country England
    Document type Editorial
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-7-38
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Does the immune reaction cause malignant transformation by disrupting cell-to-cell or cell-to-matrix communications?

    Prehn, Richmond T

    Theoretical biology & medical modelling

    2007  Volume 4, Page(s) 16

    Abstract: TUMOR PROGRESSION: In many (perhaps in all) tumor systems, a malignant cancer is preceded by a benign lesion. Most benign lesions do not transform to malignancy and many regress. The final transformative step to malignancy differs from the preceding ... ...

    Abstract TUMOR PROGRESSION: In many (perhaps in all) tumor systems, a malignant cancer is preceded by a benign lesion. Most benign lesions do not transform to malignancy and many regress. The final transformative step to malignancy differs from the preceding steps in, among other things, that it often occurs in the absence of the original carcinogenic stimulus.
    Mechanism of immunostimulation: Relatively low titers of specific immune reactants are known to stimulate, but cell-to-cell or cell-to-matrix interactions appear to be major inhibitors of tumor-growth. Therefore, it seems reasonable to hypothesize that the mechanism of immunostimulation may be an interference with cell-to-cell or cell-to-matrix communication by a sub-lethal immune-reaction.
    Discussion: While the above hypothesis remains unproven, some evidence suggests that immunity may have a major facilitating effect on tumor growth especially at the time of malignant transformation. There is even some evidence suggesting that transformation in vivo may seldom occur in the absence of immunostimulation of the premalignant lesion. Positive selection by the immune reaction may be the reason that tumors are immunogenic.
    MeSH term(s) Animals ; Cell Communication/immunology ; Cell Transformation, Neoplastic/immunology ; Cell Transformation, Neoplastic/metabolism ; Cell Transformation, Neoplastic/pathology ; Extracellular Matrix/immunology ; Extracellular Matrix/metabolism ; Extracellular Matrix/pathology ; Humans ; Neoplasms/immunology ; Neoplasms/metabolism ; Neoplasms/pathology
    Language English
    Publishing date 2007-05-04
    Publishing country England
    Document type Journal Article ; Review
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-4-16
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: The Initial Immune Reaction to a New Tumor Antigen Is Always Stimulatory and Probably Necessary for the Tumor's Growth

    Richmond T. Prehn

    Clinical and Developmental Immunology, Vol

    2010  Volume 2010

    Keywords Immunologic diseases. Allergy ; RC581-607 ; Specialties of internal medicine ; RC581-951 ; Internal medicine ; RC31-1245 ; Medicine ; R ; DOAJ:Allergy and Immunology ; DOAJ:Medicine (General) ; DOAJ:Health Sciences
    Language English
    Publishing date 2010-01-01T00:00:00Z
    Publisher Hindawi Publishing Corporation
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  10. Article ; Online: The paradoxical effects of splenectomy on tumor growth.

    Prehn, Richmond T

    Theoretical biology & medical modelling

    2006  Volume 3, Page(s) 23

    Abstract: Background: There is a vast and contradictory literature concerning the effect of the spleen and particularly of splenectomy on tumor growth. Sometimes splenectomy seems to inhibit tumor growth, but in other cases it seems, paradoxically, to facilitate ... ...

    Abstract Background: There is a vast and contradictory literature concerning the effect of the spleen and particularly of splenectomy on tumor growth. Sometimes splenectomy seems to inhibit tumor growth, but in other cases it seems, paradoxically, to facilitate both oncogenesis and the growth of established tumors.
    Approach: In this essay I have selected from this large literature a few papers that seem particularly instructive, in the hope of extracting some understanding of the rules governing this paradoxical behavior.
    Conclusion: In general, whether splenectomy enhances or inhibits tumor growth seems to depend primarily upon the ratio of spleen to tumor. Small proportions of spleen cells usually stimulate tumor growth, in which case splenectomy is inhibitory. Larger proportions of the same cells, especially if they are from immunized animals, usually inhibit tumor growth, in which case splenectomy results in tumor stimulation.
    MeSH term(s) Animals ; Cell Division ; Disease Models, Animal ; Humans ; Mice ; Mice, Inbred C57BL ; Neoplasm Transplantation/pathology ; Neoplasms/immunology ; Neoplasms/pathology ; Neoplasms/therapy ; Splenectomy ; Thymectomy
    Language English
    Publishing date 2006-06-26
    Publishing country England
    Document type Journal Article
    ZDB-ID 2156462-0
    ISSN 1742-4682 ; 1742-4682
    ISSN (online) 1742-4682
    ISSN 1742-4682
    DOI 10.1186/1742-4682-3-23
    Database MEDical Literature Analysis and Retrieval System OnLINE

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