Human monocytes and neutrophils play major roles in clearing bacteria from human blood and tissues. We found that the herpes virus entry mediator (HVEM) was highly expressed in monocytes and neutrophils, and its interaction with "homologous to lymphotoxins, shows inducible expression, and competes with herpes simplex virus glycoprotein D for HVEM/tumor necrosis factor (TNF)-related 2" (LIGHT) enhanced bactericidal activity against Listeria monocytogenes and Staphylococcus aureus. The LIGHT-HVEM interaction increased levels of phagocytosis, interleukin (IL)-8, TNF-alpha, nitric oxide (NO), and reactive oxygen species (ROS) in monocytes and neutrophils. Anti-HVEM monoclonal antibody was able to block LIGHT-induced bactericidal activity, cytokine production (IL-8 and TNF-alpha), and ROS generation. Moreover, inhibition of ROS and NO production blocked LIGHT-induced bactericidal activity. Our results indicate that the LIGHT/HVEM interaction in monocytes and neutrophils contributes to antibacterial activity.

Renal cell carcinoma (RCC), one of the most incurable malignancies, is highly resistant to chemotherapy and radiotherapy. Cytokine immunotherapy has been the standard approach, but the overall response rate is still very low. Administration of agonistic anti-4-1BB monoclonal antibody (mAb) has been shown to induce regression of several animal tumors but its effect on RCC is unknown. We show here that monotherapy with either anti-4-1BB mAb or the cytotoxic drug, 5-fluorouracil (5-FU), has little effect on established RCC, Renca tumors, but combination therapy with anti-4-1BB mAb and 5-FU eradicates the tumors in more than 70 % of mice. The regressing tumor tissues from mice receiving the combination therapy contained more apoptotic tumor cells and tumor infiltrating lymphocytes than tumor tissues from mice receiving 5-FU or anti-4-1BB mAb monotherapy. The number of lymphocytes in the spleens and tumor-draining lymph nodes (TDLNs) of the combination therapy mice was greatly increased compared to that of control or 5-FU monotherapy mice. Mice that had recovered due to the combination therapy rapidly rejected rechallenge with the tumor, pointing to the establishment of long-lasting tumor-specific memory. Our results indicate that targeting tumors with 5-FU, and immune cells with 4-1BB stimulation, could be a useful strategy for treating incurable RCC. ' 2008 Wiley-Liss, Inc.Key words: 5-FU; anti-4-1BB mAb; combined therapy; renal cell carcinoma Renal cell carcinoma (RCC) is highly metastatic and generally resistant to radiotherapy, chemotherapy and other systemic therapies. For example, 5-FU and related compounds produce an objective response rate of only 5%. Cytokine immunotherapy using interferon-a or IL-2 gives better responses and has now become the mainstay systemic treatment for RCC. However, even cytokine immunotherapy is still limited by toxic side effects and low response rates (11-19%).

The tumor necrosis factor receptor family molecule 4-1BB (CD137) has diverse roles in adaptive and innate immune responses. However, little is known of its role in bacterial infections. Previously, we showed that 4-1BB-deficient mice have enhanced susceptibility to Listeria monocytogenes infection, and mice pretreated with agonistic anti-4-1BB antibody (3E1) were much more resistant to L. monocytogenes infection than mice treated with control antibody. In this study, we report that stimulating 4-1BB by administering 3E1 in the early phase of L. monocytogenes infection is critical for promoting the survival of mice by inducing rapid infiltration of neutrophils and monocytes into L. monocytogenes-infected livers. The levels of tumor necrosis factor alpha, interleukin 6, and monocyte chemoattractant protein 1 in the livers of 3E1-treated mice increased as early as 30 min postinfection and peaked by 1 to 2 h, while those in mice treated with control antibody started to increase only at 16 h postinfection. Monocytes and neutrophils from the 3E1-treated mice had higher levels of activation markers, phagocytic activity, and reactive oxygen species than those from control mice. In vitro stimulation of 4-1BB induced the production of the inflammatory cytokines/chemokines of neutrophils, but not those of monocytes. These results suggest that 4-1BB stimulation of neutrophils in the early phase of L. monocytogenes infection causes rapid production of inflammatory cytokines/chemokines and that the subsequent infiltration of neutrophils and monocytes is crucial for eliminating the infecting L. monocytogenes.Listeria monocytogenes is a gram-positive intracellular pathogen responsible for listeriosis, a life-threatening infection in immunocompromised patients, newborns, or elderly people. The murine model of listeriosis has been used to investigate immune responses to bacterial infection (11). L. monocytogenes infects both phagocytic and nonphagocytic cells, escapes from intracellular vacuoles into the cytosol by secreting listeriolysin, replicates, and spreads to neighboring cells by actinbased motility. Intravenous (i.v.) bacteria are rapidly cleared from the bloodstream; most of them are taken up by the liver and spleen within 10 min of infection. Although T-cell-dependent adaptive immune responses are required to clear L. monocytogenes infection, they take several days to develop. Therefore, early control of the infection is critical for the survival of mice and primarily depends on innate immunity (5); indeed, it has even been shown that lymphocytes are detrimental during the early innate immune response to L. monocytogenes (4). Neutrophils and monocytes/macrophages are thought to be the main cells responsible for killing L. monocytogenes during the innate immune response. Thus, depletion of neutrophils from mice by using anti-Gr-1 antibodies greatly enhances their susceptibility to infection with L. monocytogenes (35), and the increased number of neutrophils resulting from deficiency in LFA-1 in mice confers resistance to...

Summary 4-1BB costimulates T cells to carry out effector functions such as eradication of established tumours. 4-1BB (CD137) is a member of the TNF receptor family, and its triggering by either 4-1BB ligand or antibody ligation induces T-cell activation and growth. We analysed tumour-infiltrating lymphocytes (TIL) in the experimental B16F10 melanoma model to determine the mechanisms involved in 4-1BB-mediated tumour suppression. 4-1BB +/+ mice survived longer than 4-1BB -/-mice, and survival was further prolonged by triggering 4-1BB with an agonistic mAb. The number of metastatic B16F10 colonies in the lung was much greater in 4-1BB -/-mice than in their 4-1BB +/+ littermates. Administration of agonistic anti-4-1BB mAb increased the number of TIL in the tumour masses in the lungs of 4-1BB +/+ mice. The numbers of CD4 + T, CD8 + T and CD11b + TIL increased in these mice. Anti-4-1BB mAb induced not only CD8 + 4-1BB + T cells but also a CD8 + IFN-γ + T-cell population. B16F10 cells from the lungs of anti-4-1BB-treated mice showed enhanced expression of MHC class Ι and II antigens compared with the same cells from control IgG-treated mice. Thus, the increase in number of CD8 + T cells and enhanced MHC Ι and II expression in B16F10 cells that result from augmented IFN-γ production in response to anti-4-1BB mAb may lead to suppression of tumour growth and metastasis.