Differential responsiveness to IL-2, IL-7, and IL-15 common receptor gamma chain cytokines by antigen-specific peripheral blood naive or memory cytotoxic CD8+ T cells from healthy donors and melanoma patients.

Common receptor gamma chain (c-gamma) cytokines (CKs) support proliferation of CD8+ T cells in presence or absence of antigen triggering and help maintaining the immunologic memory. We addressed the effects of low (< or = 5 ng/mL)-dose interleukin (IL)-2, IL-7, or IL-15 on human naive and memory antigen-specific CD8+ T cells. Peripheral blood CD8+ lymphocytes proliferated with decreasing efficiency in response to IL-15, IL-7, and IL-2. Of note, IL-15 preferentially promoted expansion of CD45RA/CD8+ T-cell memory subset. Accordingly, cytotoxic T lymphocytes specific for cytomegalovirus-derived antigens from seropositive donors proliferated in response to IL-15 and, to lesser extent to IL-7, but poorly to IL-2. CD8+ T cells were then pretreated with CK before antigen stimulation using, as read out, specific cytotoxic activity. After the pretreatment with IL-15, but not IL-2, previously experienced viral antigens induced vigorous cytotoxic responses. Minor effects of IL-7 were also detectable. In contrast, IL-2 best supported the cytotoxic T lymphocyte generation from prevailingly naive CD8 T cells from HLA-A*0201 healthy donors, specific for L27Melan-A/MART-126-35 melanoma-associated antigen. Cells from melanoma patients were tested before and after Melan-A/MART-1-targeted antigen-specific immunotherapy. Untreated patients showed heterogeneous patterns of responsiveness to c-gamma CK. However, when naive patients whose CD8+ T cells best responded to IL-2 were vaccinated, a modified responsiveness pattern was detectable. After immunization, cells displayed a significantly higher response to IL-15 than to IL-2 pretreatment. Thus, responsiveness to c-gamma CK is critically influenced by naive or memory status of peripheral blood CD8+ T cells.

Whole blood assessment of antigen specific cellular immune response by real time quantitative PCR: a versatile monitoring and discovery tool.

BACKGROUND: Monitoring of cellular immune responses is indispensable in a number of clinical research areas, including microbiology, virology, oncology and autoimmunity. Purification and culture of peripheral blood mononuclear cells and rapid access to specialized equipment are usually required. We developed a whole blood (WB) technique monitoring antigen specific cellular immune response in vaccinated or naturally sensitized individuals. METHODS: WB (300 microl) was incubated at 37 degrees C with specific antigens, in the form of peptides or commercial vaccines for 5-16 hours. Following RNAlater addition to stabilize RNA, the mixture could be stored over one week at room temperature or at 4 degrees C. Total RNA was then extracted, reverse transcribed and amplified in quantitative real-time PCR (qRT-PCR) assays with primers and probes specific for cytokine and/or chemokine genes. RESULTS: Spiking experiments demonstrated that this technique could detect antigen specific cytokine gene expression from 50 cytotoxic T lymphocytes (CTL) diluted in 300 microl WB. Furthermore, the high sensitivity of this method could be confirmed ex-vivo by the successful detection of CD8+ T cell responses against HCMV, EBV and influenza virus derived HLA-A0201 restricted epitopes, which was significantly correlated with specific multimer staining. Importantly, a highly significant (p = 0.000009) correlation between hepatitis B surface antigen (HBsAg) stimulated IL-2 gene expression, as detectable in WB, and specific antibody titers was observed in donors vaccinated against hepatitis B virus (HBV) between six months and twenty years before the tests. To identify additional markers of potential clinical relevance, expression of chemokine genes was also evaluated. Indeed, HBsAg stimulated expression of MIP-1beta (CCL4) gene was highly significantly (p = 0.0006) correlated with specific antibody titers. Moreover, a longitudinal study on response to influenza vaccine demonstrated a significant increase of antigen specific IFN-gamma gene expression two weeks after immunization, declining thereafter, whereas increased IL-2 gene expression was still detectable four months after vaccination. CONCLUSION: This method, easily amenable to automation, might qualify as technology of choice for high throughput screening of immune responses to large panels of antigens from cohorts of donors. Although analysis of cytokine gene expression requires adequate laboratory infrastructure, initial antigen stimulation and storage of test probes can be performed with minimal equipment and time requirements. This might prove important in "field" studies with difficult access to laboratory facilities.

High expression of indoleamine 2,3-dioxygenase gene in prostate cancer.

Arginase 2, inducible- and endothelial-nitric-oxide synthase (iNOS and eNOS), indoleamine 2,3-dioxygenase (IDO) and TGF-beta, might impair immune functions in prostate cancer (PCA) patients. However, their expression was not comparatively analysed in PCA and benign prostatic hyperplasia (BPH). We evaluated the expression of these genes in PCA and BPH tissues. Seventy-six patients (42 BPH, 34 PCA) were enrolled. Arginase 2, eNOS and iNOS gene expression was similar in BPH and PCA tissues. TGF-beta1 gene expression was higher in BPH than in PCA tissues (p=0.035). IDO gene expression was more frequently detectable (p=0.00007) and quantitatively higher (p=0.00001) in PCA tissues than in BPH. IDO protein, expressed in endothelial cells from both BPH and PCA, was detectable in tumour cells in PCA showing evidence of high specific gene expression. In these patients, IDO gene expression correlated with kynurenine/tryptophan ratio in sera. Thus high expression of IDO gene is specifically detectable in PCA.

New dimensions in tumor immunology: what does 3D culture reveal?

Experimental models indicate that tumor cells in suspension, unlike solid tumor fragments, might be unable to produce life-threatening cancer outgrowth when transferred to animal models, irrespective of the number of cells transferred, although they induce specific immune responses. Human tumor cells cultured in three dimensions display increased pro-angiogenic capacities and resistance to interferons, chemotherapeutic agents or irradiation, as compared with cells cultured in two-dimensional (2D) monolayers. Tumor cells cultured in three dimensions were also shown to be characterized by defective immune recognition by cytotoxic T lymphocytes (CTLs) specific for tumor-associated antigens (TAAs) and by a capacity to inhibit CTL proliferation and dendritic cell (DC) functions. Downregulation of human leukocyte antigen (HLA) or TAA expression and high production of lactic acid might play a role in the elicitation of these effects. Here, we propose that growth in 3D architectures might provide new insights into tumor immunology and could represent an integral missing component in pathophysiological tumor immune escape mechanisms.

Economic burden of surgical site infections at a European university hospital.

OBJECTIVE: To quantify the economic burden of in-hospital surgical site infections (SSIs) at a European university hospital. DESIGN: Matched case-control study nested in a prospective observational cohort study. SETTING: Basel University Hospital in Switzerland, where an average of 28,000 surgical procedures are performed per year. METHODS: All in-hospital occurrences of SSI associated with surgeries performed between January 1, 2000, and December 31, 2001, by the visceral, vascular, and traumatology divisions at Basel University Hospital were prospectively recorded. Each case patient was matched to a control patient by age, procedure code, and National Nosocomial Infection Surveillance System risk index. The case-control pairs were analyzed for differences in cost of hospital care and in provision of specialized care. RESULTS: A total of 6,283 procedures were performed: 187 SSIs were detected in inpatients, 168 of whom were successfully matched with a control patient. For case patients, the mean additional hospital cost was SwF-19,638 (95% confidence interval [CI], SwF-8,492-SwF-30,784); the mean additional postoperative length of hospital stay was 16.8 days (95% CI, 13-20.6 days); and the mean additional in-hospital duration of antibiotic therapy was 7.4 days (95% CI, 5.1-9.6 days). Differences were primarily attributable to organ space SSIs (n = 76). CONCLUSIONS: In a European university hospital setting, SSIs are costly and constitute a heavy and potentially preventable burden on both patients and healthcare providers.

Use of multicellular tumor spheroids to dissect endothelial cell-tumor cell interactions: a role for T-cadherin in tumor angiogenesis.

This study addresses establishment of an "in vitro" melanoma angiogenesis model using multicellular tumor spheroids (MCTS) of differentiated (HBL) or undifferentiated (NA8) melanoma cell lines. DNA microarray assay and qRT-PCR indicated upregulation of pro-angiogenic factors IL-8, VEGF, Ephrin A1 and ANGPTL4 in NA8-MCTSs (vs. monolayers) whereas these were absent in MCTS and monolayer cultures of HBL. Upon co-culture with endothelial cell line HMEC-1 NA8-MCTS attract, whereas HBL-MCTS repulse, HMEC-1. Overexpression of T-cadherin in HMEC-1 leads to their increased invasion and network formation within NA8-MCTS. Given an appropriate angiogenic tumor microenvironment, T-cadherin upregulation on endothelial cells may potentiate intratumoral angiogenesis.

Differential effects of the tryptophan metabolite 3-hydroxyanthranilic acid on the proliferation of human CD8+ T cells induced by TCR triggering or homeostatic cytokines.

Production of indoleamine 2,3-dioxygenase (IDO) by tumor cells, leading to tryptophan depletion and production of immunosuppressive metabolites, may facilitate immune tolerance of cancer. IDO gene is also expressed in dendritic cells (DC) upon maturation induced by lipopolysaccarides or IFN. We investigated IDO gene expression in melanoma cell lines and clinical specimens as compared to mature DC (mDC). Furthermore, we explored effects of L-kynurenine (L-kyn) and 3-hydroxyanthranilic acid (3-HAA) on survival and antigen-dependent and independent proliferation of CD8(+) cells. We observed that IDO gene expression in cultured tumor cells and freshly excised samples is orders of magnitude lower than in mDC, providing highly efficient antigen presentation to CD8(+) T cells. Non toxic concentrations of L-kyn or 3-HAA did not significantly inhibit antigen-specific CTL responses. However, 3-HAA, but not L-kyn markedly inhibited antigen-independent proliferation of CD8(+) T cells induced by common receptor gamma-chain cytokines IL-2, -7 and -15. Our data suggest that CD8(+) T cell activation induced by antigenic stimulation, a function exquisitely fulfilled by mDC, is unaffected by tryptophan metabolites. Instead, in the absence of effective T cell receptor triggering, 3-HAA profoundly affects homeostatic proliferation of CD8(+) T cells.

Nonreplicating recombinant vaccinia virus expressing CD40 ligand enhances APC capacity to stimulate specific CD4+ and CD8+ T cell responses.

Recombinant poxviruses expressing immunomodulatory molecules together with specific antigens represent powerful vaccines for cancer immunotherapy. Recently, we and others have demonstrated, in vitro and in vivo, that coexpression of CD80 and CD86 costimulatory molecules enhances the immunogenic capacity of a recombinant vaccinia virus (rVV) encoding different tumor-associated antigens. To further investigate the capacity of these vectors to provide ligands for different costimulatory pathways relevant in the generation of T cell responses, we constructed a recombinant virus (rVV) expressing CD40 ligand or CD154 (CD154rVV). Upon binding the CD40 receptor expressed on antigen presenting cells (APC), this molecule, physiologically expressed on activated CD4+ T cells, increases their antigen presentation and immunostimulatory capacities. Therefore, we evaluated the effects of CD154rVV infection on APC activation and its consequences on T cell stimulation. CD154rVV infection of autologous fibroblasts, monocytes, or iDC promoted the expression of a number of cytokines, including GM-CSF, TNF-alpha, and IL-15 in iDC. Most importantly, IL-12 p40 gene expression and protein secretion were induced by CD154rVV but not by wild-type VV (WT VV) in either CD14+ cells or iDC, and these effects could be blocked by anti-CD40 monoclonal antibodies. Furthermore, phenotypic characterization of CD154rVV infected iDC revealed enhanced expression of CD83 and CD86 surface markers as compared with wild-type vaccinia virus infection. As expected, VV infection triggered cytokines gene expression in cultures including APC and T cells from VV immune donors. However, cytokine genes typically expressed by T cell receptor triggered T cells such as those encoding IL-2 and IFN-gamma, or T cell proliferation, were detectable to a significantly higher extent in CD154rVV infected cultures, as compared with WT VV. Activation of specific CD8+ T cells was then investigated using MART-1/Melan-A(27-35) epitope as the model of tumor-associated antigen (TAA). In the presence of CD154rVV activated APCs, significantly higher numbers of specific cytotoxic CD8+ T cells were detected, as compared with cultures performed in the presence of WT VV or in the absence of virus. Taken together, these data indicate that functional CD154 expression from rVV infected cells promotes APC activation, thereby enhancing antigen-specific T cell generation. Such a recombinant vector might help bypass the requirement for activated helper cells during CTL priming, thus qualifying as a potentially relevant vector in the generation of CD8+ T cell responses in cancer immunotherapy.