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B7-H1, a recently described B7 family member, has been reported to negatively regulate T-cell function in most cancer cells. In this study, we sought to investigate B7-H1 expression in four uveal melanoma (UM) cells (OCM1, SP6.5, OM431 and VUP) to determine the functional significance of B7-H1 expression in T-cell immune response. Using flow cytometry(More)
In addition to its property of enhancing major histocompatibility complex (MHC) class II expression, the class II transactivator (CIITA) was recently demonstrated to be involved in T helper type 1/type 2 (Th1/Th2) differentiation by regulating interleukin-4 (IL-4) gene transcription. There was however, controversy regarding whether CIITA promotes or(More)
A group of 15-aa-long Trichosanthin-derived peptides was synthesized and screened based on their differential abilities to induce low-responsiveness in mouse strains with high and low susceptibility. One of them was conjugated to form a homo-tetramer Tk-tPN. At concentrations of 0.1-50 μg/ml, Tk-tPN activated CD8(+)CD28(-) Tregs in vitro to induce immune(More)
The activity of Trichosanthin (Tk) has been attributed to its toxicity since this plant protein was used as an anti-HIV agent. However, in this study strong inhibition of human lymphoproliferation to soluble and allogeneic antigens was induced by Tk at 0.005-0.5 microg/ml without causing cell damages including apoptosis. The suppression was dependent on the(More)
It has been demonstrated in our previous work that, in the human skin-grafting model, the expression of costimulatory molecule B7H1 (PD-L1) by keratinocytes plays an essential role in inducing local tolerance via activation of IL-10-secreting T cells. This study further analyzes the role of B7H1 in differentiation of type 1 T regulatory (Tr1) cells and(More)
The nature and differentiation of regulatory CD8(+)CD28(-) T cells are poorly understood. In this study, we demonstrate that native Ag trichosanthin (Tk), a highly purified linear peptide isolated from a Chinese medicinal herb, is able to induce strong suppression of OVA-specific lymphoproliferation at low concentrations via activation of(More)
We previously reported that keratinocytes (KCs) could express B7H1 molecules and suppress allogeneic antigen-mediated immune responses through induction of IL-10-expressing T cells. The aims of this study were to investigate whether KCs could also suppress xene-antigen-mediated reactions as well as the role of B7H1 in KC-induced immunosuppression. Human T(More)
We report here that Trichosanthin (Tk), a primary active component isolated from a Chinese traditional medicinal herb, Trichosanthes kirilowii, potently inhibits lymphocyte proliferative response in vitro. We found that Tk treatment increased production of the interleukins IL-4 and IL-10, while production of IL-2 and interferon-gamma (IFN-gamma) decreased(More)
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