Article

Immunosuppressive Strategies that are Mediated by Tumor Cells

Division of Immunogenetics, Hospital de Clínicas José de San Martín, University of Buenos Aires, Buenos Aires, Argentina.
Annual Review of Immunology (Impact Factor: 39.33). 02/2007; 25(1):267-96. DOI: 10.1146/annurev.immunol.25.022106.141609
Source: PubMed

ABSTRACT

Despite major advances in understanding the mechanisms leading to tumor immunity, a number of obstacles hinder the successful translation of mechanistic insights into effective tumor immunotherapy. Such obstacles include the ability of tumors to foster a tolerant microenvironment and the activation of a plethora of immunosuppressive mechanisms, which may act in concert to counteract effective immune responses. Here we discuss different strategies employed by tumors to thwart immune responses, including tumor-induced impairment of antigen presentation, the activation of negative costimulatory signals, and the elaboration of immunosuppressive factors. In addition, we underscore the influence of regulatory cell populations that may contribute to this immunosuppressive network; these include regulatory T cells, natural killer T cells, and distinct subsets of immature and mature dendritic cells. The current wealth of preclinical information promises a future scenario in which the synchronized blockade of immunosuppressive mechanisms may be effective in combination with other conventional strategies to overcome immunological tolerance and promote tumor regression.

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Available from: Eduardo M Sotomayor, Feb 21, 2014
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    • "In addition to sense the presence of exogenous antigens, immune system is also able to recognize the tumor-associated antigens and eliminate the neoplastic cells-a process called immunosurveillance [4]. Tumor cells proliferate in an immunosuppressive microenvironment, which renders their efficient clearance by the immune system inefficient [5]. DCs, owing to their excellent capacity for antigen-presentation and T-cell stimulation, have been considered as potential candidates for immunotherapy. "

    Full-text · Article · Dec 2015
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    • "The two-way interactions between DCs and T cells initiate either an immunogenic or a tolerogenic pathway, both of which can play crucial roles in tumor immunity[62]. Tumors can mimic some of the signaling pathways of the immune system, thus propagating conditions that favor immune tolerance and escaping tumor immunity[63]. It has been shown, here and in other reports, that CRC cells can confer tolerogenic behavior on MoDCs by inducing phenotypic alterations and reducing the ability to stimulate T cells. "
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    • "Passive and active immunotherapy has been successfully applied to the treatment of a wide variety of human cancers [8] and holds promise of a lifelong cure [9]. However, tumor-induced immunosuppression still represents a major obstacle to effective cell-mediated immunity and immunotherapy [3] [5]. Accordingly, more insights into the main mechanisms associated with immune responses based on tumor specific features are required to obtain successful therapeutic outcomes with immunomodulatory strategies. "
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