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Tumour cells are able to evade the immune system by using several 'escape mechanisms'. Downregulation of molecules involved in the processing and presentation of self-antigens has been reported. However, these adaptations have not been compared in metastases in different anatomical locations but derived from a single patient. We investigated three melanoma cell lines--MJT1 from the parietal lobe of the brain, MJT3 from the cerebellum and MJT5 from the left side of the neck--established from biopsies excised from a 45 year old female patient. Although human leukocyte antigen (HLA) class I was detected in all three cell lines by flow cytometry using an anti-HLA monomorphic antibody, further serological analysis demonstrated HLA B38 loss in all three cell lines, HLA B7 downregulation in MJT5 (skin metastases) and B7 loss in MJT3 and MJT1 (brain metastases) compared with the HLA type of the patient's normal autologous lymphocytes. Interferon-gamma (IFNgamma) treatment increased the expression of HLA class I and transporters associated with antigen processing 1 (TAP1) in all three cell lines. De novo HLA class II molecule expression was observed after IFNgamma treatment in MJT3 and MJT5. Western blot and reverse transcription-polymerase chain reaction results revealed heterogeneity of melanoma-associated antigen (MAA) expression in the cell lines: MJT3 cells expressed higher levels of MAAs than the other two cell lines. In conclusion, this study has demonstrated that three metastatic lesions from a single patient can have differential expression of molecules involved in antigen processing (TAP1) and presentation (HLA I and II), but that expression of these molecules is modulated by IFNgamma to a similar degree in all cell lines. In contrast, the downregulation of expression of specific MAAs between the three cell lines was unaffected by the addition of IFNgamma.

Although studies have suggested that exposure to cigarette smoke (CS) may be associated with the development of atopy, the mechanisms underlying this are not clearly understood. It has been suggested that CS impairs the barrier function of the airway epithelium, leading to increased access of allergens such as those of the house dust mite (HDM) Dermatophagoides pteronyssinus (Der p) to antigen-presenting cells, with subsequent allergic sensitization. In order to test this hypothesis, we established primary explant cultures of human bronchial epithelial cells (HBEC) in cell culture inserts, and exposed these for 20 min, 1 h, 3 h, and 6 h to CS or air in the absence or presence of 300 ng/ml Der p, and then further incubated the cultures over a period of 24 h. The HBEC cultures were assessed for changes in permeability as measured by changes in: (1) electrical resistance (ER); and (2) passage of 14C-labeled bovine serum albumin (14C-BSA) and Der p allergens across the HBEC cultures. We also assessed the effects of protease inhibitors and the antioxidant glutathione (GSH) in this experimental system. Damage to HBEC cultures was assessed by the release of [51Cr]sodium chromate from prelabeled cells, and by release of lactate dehydrogenase (LDH). Twenty minutes of exposure to CS as compared with exposure to air did not significantly alter either the ER or passage of 14C-BSA across the HBEC cultures. In contrast, incubation with Der p led to a significant increase in the permeability of HBEC cultures, an effect that was enhanced by exposure to CS but was abrogated by the specific protease inhibitors and GSH. Passage of Der p was also increased by exposure to CS. Exposure of HBEC cultures to CS led to a significant release of 51Cr and LDH from these cells as compared with cells exposed to air. This effect was augmented further when HBEC cultures were incubated with Der p. Exposure of HBEC cultures for 1 h, 3 h, and 6 h to CS led to a markedly significant dose- and time-dependent increase in the permeability of these cells. These results suggest that exposure to CS significantly enhances Der p-induced decreases in electrical resistance and the increased passage across HBEC cultures of 14C-BSA and of the Der p allergen itself.

BackgroundThe potential utility of dendritic cells (DC) as cancer vaccines has been established in early trials in human cancers. The concomitant administration of cytotoxic agents and DC vaccines has been previously avoided due to potential immune suppression by chemotherapeutics. Recent studies show that common chemotherapy agents positively influence adaptive and innate anti-tumour immune responses.ResultsWe investigated the effects of paclitaxel on human DC biologyin vitro. DCs appear to sustain a significant level of resistance to paclitaxel and maintain normal viability at concentrations of up to 100 μmol. In some cases this resistance against paclitaxel is significantly better than the level seen in tumour cell lines. Paclitaxel exposure led to a dose dependent increase in HLA class II expression equivalent to exposure to lipopolysaccharide (LPS), and a corresponding increase in proliferation of allogeneic T cells at the clinically relevant doses of paclitaxel. Increase in HLA-Class II expression induced by paclitaxel was not blocked by anti TLR-4 antibody. However, paclitaxel exposure reduced the endocytic capacity of DC but reduced the expression of key pro-inflammatory cytokines such as IL-12 and TNFα. Key morphological changes occurred when immature DC were cultured with 100 μmol paclitaxel. They became small rounded cells with stable microtubules, whereas there were little effects on LPS-matured DC.ConclusionsThe effect of paclitaxel on human monocyte derived DC is complex, but in the clinical context of patients receiving preloaded and matured DC vaccines, its immunostimulatory potential and resistance to direct cytotoxicity by paclitaxel would indicate potential advantages to co-administration with vaccines.

Live attenuated bacterial vectors, such asSalmonella typhimurium, have shown promise as delivery vehicles for DNA. We have examined two new strains ofS. typhimuriumand their impact on dendritic cell maturation (CD12-sifA/aroCmutant and WT05-ssaV/aroC, both in TML background). Strain WT05 matured dendritic cells in a more efficient way; caused higher release of cytokines TNF-α, IL-12, IL-1β; and was efficient for gene transfer. These findings suggest that the genetic background of the attenuation can influence the pattern of inflammatory immune response toSalmonellainfection.

The traditional plaque forming and TCID(50) methods to determine replication competent virus titres rely on several cycles of replication and infection to generate a plaque with an incubation period of 24-72 h post-infection typically required. We developed a method to quantify infective viral particles based on early detection of cellular events by capillary cytometry. The method uses a capillary cytometer as a precise cell counter that can discriminate infected from non-infected cells. The general protocol was developed using a Guava PCA, genetically modified HSV-1 virus and polyclonal antibodies against antigens expressed on the cell membrane. Infection was detected after 1 h incubation and a plateau in the number of infected cells was observed between 7 and 9 h. A good correlation between titres obtained by the plaque forming method and the proposed method was observed for a ratio of infected to total cells between 0.5 and 0.05. The rapid and automated analysis (10 s/1000 events acquired per sample) makes the method particularly useful for high-throughput applications. The proposed method can be extended easily to determine the titre of other viruses providing a powerful tool for virology and antiviral screening.

There are many complex relationships between tu-\ud mour cells and effector cells in the immune system.\ud These interactions are controlled predominantly by cy-\ud tokines, either within the tumour environment, or sys-\ud temically where the effector cells may be stimulated as\ud a response to the presence of the tumour. Favourable\ud clinical responses in cancer patients have been shown\ud to be associated with enhanced cell-mediated immunity\ud as well as T cell infiltration in tumours. This status\ud is controlled in part by a predominantly Th1 cytokine\ud profile e.g. IFN γ , TNF α and IL-12. Conversely, pa-\ud tients with advancing cancer may have impaired cell-\ud mediated immunity as a result of an imbalance of Th1\ud and Th2 cytokines e.g. IL-4 and IL-10 [6,9,15]. Whilst\ud cytokines have long been known to orchestrate the im-\ud mune system by allowing communication between reg-\ud ulatory and effector cells, the pleiotropic nature of these\ud molecules results in a very complex environment in\ud which to study any single molecule’s properties. Several\ud in vitro protocols have been developed,which aim to closely reflect cytokine production and T cell function in vivo. However, these assays have been developed in artificial settings and as such only allow conclusions to be drawn within a defined context [11]. The aim of this report is to outline the basic proto-cols and applications for the detection of intracellular cytokines by flow cytometry, in the context of disease monitoring.

Dendritic cell (DC)-based vaccines are promising for cancer treatment. However, there are significant problems of efficient antigen loading and practicality of current approaches. Herpes simplex virus (HSV), unlike most viruses, infects DC very efficiently suggesting its use for antigen delivery to DC. The large size of HSV allows delivery of multiple antigens (up to 30Kb), as may be beneficial for anti-cancer vaccination. However, DC infected with HSV loose the ability to become activated as is necessary for the induction of an effective immune response, probably to minimize immune responses to HSV. Thus, if the HSV- proteins which block DC activation were identified, and these removed from the virus, this might provide an ideal platform for antigen delivery to DC. We have iteratively tested an extensive range of HSV mutants with individual and combinations of genes deleted to identify the HSV DC blocking genes. This has allowed us to develop an optimal HSV backbone which activates DC similarly to LPS, rather than blocking activation as with wild type HSV. These viruses are deleted for the HSV virion host shutoff protein (vhs), which we found to be a key mediator of DC inactivation, ICP47, which blocks antigen presentation, UL43, deletion of which improves DC function, and ICP4, deletion of which blocks HSV replication. This virus significantly up-regulates levels of CD80, CD83, CD86 and MHC class I on infected cells, gives very high level transduction of DC at a low virus dose (MOI