Search

Abstract: Regulatory T (Treg) cells induce immune tolerance by suppressing host immune responses against self- or non-self-antigens. Hence, they not only play critical roles in preventing autoimmune diseases, but also may have detrimental effects on vaccines directed to cancer and infectious diseases. Understanding the antigen specificity and functional control of Treg cells will be crucial to the development of effective cancer immunotherapy. This review will discuss different subsets of Treg cells, the factors that contribute to Treg cell generation and suppressive function, and the ability of signaling through Toll-like receptor 8 to reverse the suppressive function of Treg cells. Importantly, this TLR pathway does not depend on interaction with dendritic cells, but operates independently in Treg cells, relying on TLR8 (with MyD88 as its sole receptor-proximal adaptor) to transduce signals generated by TLR8 ligands. Linking TLR signaling to the functional control of Treg cells opens intriguing opportunities to shift the balance between CD4+ T-helper and Treg cells, in ways that may improve the outcome of cancer immunotherapy. [Copyright &y& Elsevier]

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. Recent studies demonstrate the existence of CD4+ regulatory T-cells at tumor sites, implying that these Treg cells may induce antigen-specific and local immune tolerance. This review will discuss the natural ligands and their potential roles of tumor-specific CD4+ regulatory T-cells in cancer therapy. [Copyright &y& Elsevier]

Abstract: Human embryonic stem (hES) cells hold great promise in regenerative medicine. Although hES cells have unlimited self-renewal potential, they tend to differentiate spontaneously in culture. TRA-1-81 is a biomarker of undifferentiated hES cells. Quantitative characterization of TRA-1-81 expression level in a single cell helps capture the “turn-on” signal and understand the mechanism of early differentiation. Here, we report on our examination of TRA-1-81 distribution and association on a hES cell membrane using an atomic force microscope (AFM). Our results suggest that aggregated distribution of TRA-1-81 antigen is characteristic for undifferentiated hES cells. We also evaluated the TRA-1-81 expression level at ∼17,800 epitopes and ∼700 epitopes per cell on an undifferentiated cell and a spontaneously differentiated cell, respectively. The method in this study can be adapted in examining other surface proteins on various cell types, thus providing a general tool for investigating protein distribution and association at the single cell level. [Copyright &y& Elsevier]