Search

Abstract: Regulatory T cells play essential roles in inducing self-tolerance by suppressing immune responses against self such as autoantigens or non-self-antigens such as tumor and pathogenic antigens. Despite the importance of CD4+ regulatory T cells in many immune-related diseases, their antigen specificity and suppressive mechanisms remain elusive. This review discusses the natural ligands and their potential roles of tumor-specific CD4+ regulatory T cells in cancer therapy. [Copyright &y& Elsevier]

In the last few years, a great deal of efforts have been directed towards understanding the molecular basis of T cell-mediated anti-tumor immunity and elucidating the molecular nature of tumor antigens recognized by T cells. Identification of a number of major histocompatibility complex (MHC) class I-restricted melanoma antigens has led to clinical trials aimed at developing effective cancer vaccines. These studies showed some evidence of therapeutic effect on the treatment of cancer, but the exclusive use of CD8+ T cells may not be effective in eradicating tumor. This rekindles interest in the role of CD4+ T cells in antitumor immunity, which play a central role in orchestrating the host immune response against cancer. Thus, we have attempted to identify MHC class II-restricted tumor antigens recognized by tumor-specific CD4+ T cells. The identification of tumor rejection antigens provides new opportunities for the development of therapeutic strategies against cancer. This review will summarize the current status of MHC class I and class II-restricted human tumor antigens, and their potential application to cancer treatment. [Copyright &y& Elsevier]

Arsenic, a common highly-toxic pollutant, is mainly associated with the hydrous ferric oxides in soils and minerals. A possible mechanism for arsenic mobilization is the reductive dissolution of iron (hydr) oxides. In this paper, the possibilities of iron-reducing bacteria Shewanella oneidensis MR-1 and Shewanella sp. strain MR-4 in mobilization, oxidization and methylation of arsenic were investigated. Under laboratory conditions, the dynamics of As- and Fe-release from arsenopyrite and scorodite under microbial activities, the transformation of arsenic release from iron minerals and the environment factors affecting the arsenic release and transformation during reactions were examined. The aqueous concentrations of different forms of As were determined by a liquid chromatography–atomic fluorescence spectrometry (LC–AFS) and the new surface morphology of iron minerals was also measured and characterized using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Results indicated that As could be dissolved from arsenopyrite or scorodite and oxidized or even methylated quickly in the presence of Shewanella strains. The transformation of arsenic forms were affected by the culture temperatures, pH of environment medium, and spiked Fe(III) content in the solutions. Moreover, solid-phase analysis revealed that the morphology and mineralogy in the solid-phase products were changed, such as many wrinkle-shaped gullies were formed on surfaces of iron minerals. The amount of secondary precipitates also increased with time. The As mobility could be enhanced by the activity of dissimilatory iron-reducing bacteria in the environment. This study provides insights into in situ remediation of As pollution. [ABSTRACT FROM AUTHOR]