Fibroblastic tumour stroma comprising mesenchymal stem cells (MSCs) and cancer-associated fibroblasts (CAFs) promotes the invasive and metastatic properties of tumour cells. Here we show that activated CD8+ T cell-derived extracellular vesicles (EVs) interrupt fibroblastic stroma-mediated tumour progression. Activated CD8+ T cells from healthy mice transiently release cytotoxic EVs causing marked attenuation of tumour invasion and metastasis by apoptotic depletion of mesenchymal tumour stromal cells. Infiltration of EV-producing CD8+ T cells is observed in neovascular areas with high mesenchymal cell density, and tumour MSC depletion is associated with preferential engulfment of CD8+ T cell EVs in this setting. Thus, CD8+ T cells have the capacity to protect tumour progression by EV-mediated depletion of mesenchymal tumour stromal cells in addition to their conventional direct cytotoxicity against tumour cells.

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(mAbs) injected intralesionally during the early development of B16 tumours, and this treatment markedly attenuated B16 growth. Furthermore, a lesional injection of recombinant mouse IL-10 at an early tumour site resulted in the vigorous progression of B16 tumours. These results provide evidence that Tr cells, belonging to the T helper 3/T-regulatory 1 (Th3/Tr1) type, are activated in B16-bearing hosts under the in¯uence of T helper 2 (Th2) cytokines, mainly IL-10 (produced at early tumour lesions), and that this regulatory T-cell population functions as a suppressor of anti-B16 immunity.

In vivo and in vitro T-cell-activating ability of murine epidermal cells (EC) was investigated in acutely barrier-disrupted skin by extraction of epidermal lipids with acetone or removal of corneocytes by tape stripping. Contact sensitivity (CS) to 2,4-dinitrofluorobenzene (DNFB) and picryl chloride (PCl) and contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) were significantly augmented when challenged or sensitized at sites treated with acetone 24 h before, compared with the intact skin. CS to DNFB was also enhanced by tape stripping, but not by water rubbing, suggesting that physical stress or a toxic effect of acetone was not responsible for the augmentation. Semi-quantification of TCSA-EC photoadducts showed markedly increased permeability of hapten in the epidermis 24 h after acetone treatment. Bioactive IL-1alpha was more pronounced in barrier-disrupted than in intact skin. Lymph node T cells from PCl-sensitized mice proliferated significantly more in a hapten-specific and co-stimulatory molecule-dependent manner in response to trinitrophenylated (TNP) EC from acetone-treated skin than to those from untreated skin. Immunofluorescence staining of epidermal sheets and flow cytometric analysis of dispersed EC showed that subpopulations of Langerhans cells (LC) in acetone-rubbed or tape-stripped skin expressed major histocompatibility complex class II CD54 and CD86 molecules at levels higher than the rest of LC and LC from water-treated or untreated epidermis. Therefore, not only increased permeability of hapten through the epidermis but also altered immune functions of EC potentiate T-cell activation in acute barrier disruption. Such augmentation of immune reactivity may be critical to elimination of environmental noxious agents that penetrate easily into the barrier-disrupted epidermis.

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Exosomes are representative extracellular vesicles (EV) derived from multivesicular endosomes (MVE) and have been described as new particles in the communication of neighborhood and/or distant cells by serving as vehicles for transfer between cells of membrane and cytosolic proteins, lipids, and nucleotides including micro (mi) RNAs. Exosomes from immune cells and tumor cells act in part as a regulator in tumor immunology. CD8+ T cells that show potent cytotoxic activity against tumor cells reside as an inactive naïve form in the T‐cell zone of secondary lymphoid organs. Once receiving tumor‐specific antigenic stimulation by dendritic cells (DC), CD8+ T cells are activated and differentiated into effector CTL. Subsequently, CTL circulate systemically, infiltrate into tumor lesions through the stromal neovasculature where mesenchymal stromal cells, for example, mesenchymal stem cells (MSC) and cancer‐associated fibroblasts (CAF), abundantly exist, destroy mesenchymal tumor stroma in an exosome‐mediated way, go into tumor parenchyma, and attack tumor cells by specific interaction. DC‐derived and regulatory T (Treg) cell‐derived exosomes, respectively, promote and inhibit CTL generation in this setting. In this review, we describe the roles of exosomes from immune cells and tumor cells on the regulation of tumor progression.

H-2K b -restricted tumor epitope peptides, including tyrosinase-related protein 2 residues 181-188 (TRP-2) and connexin 37 residues 52-59 (MUT1), were applied to permeability barrier-disrupted C57BL͞6 (B6) mouse skin from which the stratum corneum of the epidermis had been removed by tape-stripping. This procedure primed tumor-specific cytotoxic T lymphocytes (CTLs) in the lymph nodes and spleen, protected mice against subsequent challenge with corresponding tumor cells, and suppressed the growth of established tumors. Preventive and therapeutic effectiveness was correlated with the frequency of tumor-specific CTL precursors. MHC class II Ia b؉ cells separated from tape-stripped skin, compared with those from intact skin, exhibited a strong antigen-presenting capacity for CTL, suggesting that CTL expansion after peptide application is primarily mediated by epidermal Langerhans cells. Thus, percutaneous peptide immunization via barrier-disrupted skin provides a simple and noninvasive means of inducing potent anti-tumor immunity which may be exploited for cancer immunotherapy. One of the principal goals in tumor immunoprophylaxis and therapy is induction of anti-tumor responses by generating sufficient numbers of tumor antigen-specific cytotoxic T lymphocytes (CTLs). In tumor bearers, however, not only effective CTL priming but also recognition and effective lysis of tumor cells by CTLs are often blocked or attenuated by down-regulated expression of major histocompatibility complex (MHC) class I antigens and of costimulatory and adhesion molecules on tumorcell surfaces (1), suggesting one evasion mechanism of tumor cells which affects immune surveillance. Therefore, establishment of efficient CTL priming strategies is an important issue for cancer immunotherapy.Dendritic cells are potent antigen-presenting cells distributed widely at epithelial surfaces which interface with the external environment to facilitate efficient antigen trapping (2, 3). Because of high levels of expression of MHC class I antigen and costimulatory and adhesion molecules, tumor-specific CTLs are efficiently induced with tumor antigen-or peptide-loaded dendritic cells (4-7). Studies in animal models have shown the potential of dendritic cell-based tumor immunotherapy to elicit protective anti-tumor immune responses, and the validity of such an approach has also been confirmed in humans (8-10). While understanding of the mechanism of propagation of dendritic cells under cytokine influence has progressed at a rapid pace, the intricate manipulations required for in vitro preparation of large numbers of dendritic cells in a form appropriate for immunotherapy seem to be a major drawback in current immunotherapeutic strategies.We have reported that disruption of the skin barrier results in not only enhanced permeability but also alterations in the immunoregulatory function of the skin in such a way that epidermal Langerhans cells (LCs) function as vigorous antigen presenters for T-helper cells (11). Various studies have shown that LCs target tumo...

Interactions between chemokines and chemokine receptors are involved in migration and invasion of lymphoma cells. We investigated expression profiles of CXCR3 and CCR4 by immunohistochemistry and flow cytometry, and their biologic behaviors by real-time horizontal chemotaxis assay in cutaneous T cell and NK/T-cell lymphomas (TCLs). Tumor cells in mycosis fungoides (MF) constantly expressed CXCR3 at the patch stage, and expressed CCR4 at the tumor stage and in the folliculotropic variant of MF. Neoplastic cells at the plaque stage expressed CXCR3 and/or CCR4. Sezary cells in the dermis and circulation were positive for CCR4. Epidermotropic atypical cells in pagetoid reticulosis expressed CXCR3. CD30 cells exclusively expressed CCR4 in anaplastic large-cell lymphoma, and CXCR3 and/or CCR4 in lymphomatoid papulosis. In CD8TCL and extranodal NK/TCL characterized by extensive epidermotropism, tumor cells were positive for CXCR3. These data demonstrated preferential expression of CXCR3 in epidermotropic tumor cells, and of CCR4 in dermis-based lymphomas. In chemotaxis assays, CCR4 tumor cells in MF and CXCR3 tumor cells in CD8TCL migrated to thymus and activation-regulated chemokine and inducible protein-10, respectively. Therefore, spatial and temporal interactions between chemokine receptors and their ligands seem to dictate recruitment and retention of lymphoma cells in the skin.