Assessment of oxacillin salt agar for detection of MRSA identified by presence of the mecA gene

Progressive growth of immunogenic murine tumors elicits a tumor-specific but functionally deficient T-cell immune response in the draining lymph nodes. These T cells, referred to as "pre-effector" cells could be induced in vitro to differentiate into mature immune effector cells, capable of mediating the regression of established metastases. Initially, tumor cells were used to stimulate the in vitro maturation of pre-effector cells. Alternatively, we found that pre-effector cells could be activated by sequential stimulation with anti-CD3 and interleukin-2 in the absence of tumor cells. In adoptive immunotherapy, these activated cells mediated therapeutic effects that were exquisitely specific to the tumor that triggered the pre-effector cell response in vivo. Since the anti-CD3 interaction with T cells is polyclonal, the activated lymph node cell population must also contain a significant number of T cells that do not have tumor specificity. In an attempt to selectively activate tumor-sensitized pre-effector cells, we recently utilized superantigenic bacterial toxins as T-cell stimuli for effector cell generation. Superantigens combine with major histocompatibility class II molecules to form the ligands that stimulate T cells bearing distinct T-cell receptor V beta elements. Lymph node cells draining the MCA 205 sarcoma stimulated with staphylococcal enterotoxins A (SEA), B (SEB), or C2 (SEC2) resulted in selective expansions of V beta 3 and 11, V beta 3 and 8, or V beta 8.2 T cells, respectively. Adoptive immunotherapy experiments revealed that SEB- and SEC2-, but not SEA- stimulated cells, mediated tumor-specific eradication of pulmonary metastases.(ABSTRACT TRUNCATED AT 250 WORDS)     

Adenoviral gene delivery elicits distinct pulmonary-associated T helper cell responses to the vector and to its transgene

Replication-deficient adenovirus (Ad) vectors are effective to specifically target the respiratory epithelium for either corrective gene therapy such as cystic fibrosis or for mucosal immunization. As a consequence of transducing the lower respiratory tract with an E1/E3 deleted Ad5 vector, host responses have been characterized by the duration of transgene expression and by the induction of CTL responses. However, limited emphasis has been devoted to understanding the contribution of CD4+ T cell responses to the Ad vector. Both CD4+ and CD8+ T cells migrate into the lung following sequential intratracheal Ad5 transgene instillations. Isolated CD3+ T lymphocytes from the lungs were predominantly of the Th2 type, and after cell sorting, the IL-4-producing T cells were largely CD4+, while IFN-gamma expression was associated with both CD4+ and CD8+ T cells. Ab responses to the Ad5 vector and to the expressed transgene beta-galactosidase (beta gal) revealed elevated bronchial and serum IgA and IgG Abs with low neutralization titers. Analysis of serum IgG subclass responses showed IgG1 and IgG2b with lower IgG2a Abs to Ad5 and IgG2a and IgG2b Ab responses to beta gal. Ad5-specifc CD4+ T cells produced both Th1 (IFN-gamma and IL-2)- and Th2 (IL-4, IL-5, IL-6)-type cytokines, while beta gal-specific CD4+ T cells secreted IFN-gamma and IL-6. This study provides direct evidence for the concomitant induction of Th2- with Th1-type responses in both the pulmonary systemic and mucosal immune compartments to the Ad5 vector as well as a Th1-dominant response to the transgene.     

Combination chemotherapy and IL-15 administration induce permanent tumor regression in a mouse lung tumor model: NK and T cell-mediated effects antagonized by B cells

Previous studies have demonstrated that IL-15 administration after cyclophosphamide (CY) injection of C57BL/6J mice bearing the i.m. 76-9 rhabdomyosarcoma resulted in a significant prolongation of life. In the present study, we investigated the immune response against the 76-9 experimental lung metastases after CY + IL-15 therapy. Administration of CY + IL-15, but not IL-15 alone, induced prolongation of life and cures in 32% of mice bearing established experimental pulmonary metastases of 76-9 tumor. The CY + IL-15 therapy resulted in increased levels of NK1.1+/LGL-1+ cells, and CD8+/CD44+ T cells in PBL. In vitro cytotoxic assay of PBL indicated the induction of lymphokine-activated killer cell activity, but no evident tumor-specific class I-restricted lytic activity. Survival studies showed that the presence of NK and T lymphocytes is necessary for successful CY + IL-15 therapy. Experiments using knockout mice implied that either alphabeta or gammadelta T cells were required for an antitumor effect induced by CY + IL-15 therapy. However, mice lacking in both alphabeta and gammadelta T cells failed to respond to combination therapy. Cured B6 and alphabeta or gammadelta T cell-deficient mice were immune to rechallenge with 76-9, but not B16LM tumor. B cell-deficient mice showed a significant improvement in the survival rate both after CY and combination CY + IL-15 therapy compared with normal B6 mice. Overall, the data suggest that the interaction of NK cells with tumor-specific alphabeta or gammadelta T lymphocytes is necessary for successful therapy, while B cells appear to suppress the antitumor effects of CY + IL-15 therapy.     

Direct activation of human CD8+ cytotoxic T lymphocytes by interleukin-18

Direct activation of human cytotoxic T lymphocytes (CTL) by interleukin (IL)-18 was observed in a system in which CTL effective against autologous tumor cells were generated. Peripheral blood mononuclear cells (PBMC) from tumor-bearing patients, after removal of natural killer (NK) cells, were cultured in a medium containing IL-1, -2, -4, and -6, with or without IL-18, and stimulated with autologous tumor cells. IL-18 increased the activity of the CTL and the proportion of autologous CD8+ T cells present after 28 days in the induction culture. When purified CD8+ T cells were cultured in the presence of IL-18 and IL-2 for 7 days, the CTL showed enhanced cytotoxic activity against autologous tumor cells. Moreover, a purified CD8+ T cell population, which did not exhibit any apparent cytotoxic activity against autologous tumor cells, displayed cytotoxic activity after 7-day incubation with IL-18. These results suggest that IL-18 may be useful to generate autologous CTL in humans and may thereby contribute to adoptive immunotherapy for tumors.     

Plasma levels and gene expression of granulocyte colony-stimulating factor, tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, IL-8, and soluble intercellular adhesion molecule-1 in neonatal early onset sepsis

We have previously reported that T lymphocytes proliferating in vitro to the hapten trinitrochlorobenzene (TNCB) exhibit a very restricted V beta gene usage and response to TNCB is limited to T-cell receptors (TCR) composed of V beta 8.2 in combination with V alpha 3.2, V alpha 8 and V alpha 10. This paper investigates the role played by T lymphocytes expressing the V beta 8.2 gene segment in the contact sensitivity (CS) reaction to TNCB in the intact mouse and in its passive transfer into naive recipient mice. Mice injected with monoclonal antibodies to V beta 8 are unable to develop CS upon immunization with TNCB and 4-day TNCB-immune lymph node cells from mice that had been depleted in vivo or in vitro of V beta 8+ T lymphocytes fail to transfer CS. However, when separated V beta 8+ and V beta 8- cells were used for passive transfer, it was found that V beta 8+ T lymphocytes failed to transfer CS when given alone to recipient mice and a V beta 8- population was absolutely required. Further analysis revealed that within the V beta 8- population, T lymphocytes expressing the gamma delta TCR were fundamental to allow transfer of the CS reaction. These gamma delta cells were found to be antigen non-specific, genetically unrestricted and to rearrange the V gamma 3 gene segment. This indicates that transfer of the CS reaction requires cross-talk between V beta 8+ and gamma delta+ T lymphocytes, thus confirming our previous results obtained using TNCB-specific T-cell lines. Time-course experiments showed that V beta 8+ lymphocytes taken 4-24 days after immunization with TNCB were able to proliferate and produce interleukin-2 (IL-2) in response to the specific antigen in vitro. Similar time-course experiments were then undertaken using the passive transfer of the CS reaction system. The results obtained confirm that TNCB-specific V beta 8+ T lymphocytes are present in the lymph nodes of immunized mice from day 4 to day 24, and reveal that gamma delta+ T lymphocytes are active for a very short period of time, i.e. days 4 and 5 after immunization. In fact, TNCB-specific V beta 8+ cells are able to transfer CS when taken 4-24 days after immunization, providing the accompanying V beta 8- or gamma delta+ T lymphocyte are obtained 4 days after immunization. In contrast, injection of V beta 8+ T lymphocytes together with V beta 8- or gamma delta+ T lymphocytes that had been taken 2 or 6 days after immunization, failed to transfer significant CS into recipient mice. Taken together, our results confirm that cross-talk between V beta 8+ and gamma delta+ T lymphocytes is necessary for full development of the CS reaction and may explain why the CS reaction in the intact mouse lasts up to 21 days after immunization while the ability of immune lymph node cells to transfer CS is limited to days 4 and 5 after immunization.     

Generation of cytotoxic immune responses during the progression of a rat glioma

Cytotoxic T lymphocytes specific for tumor-associated antigens are produced by exposing animals to tumor cells and stimulating lymphocytes from animals immunized in vitro with tumor cells and small amounts of interleukin-2 (IL-2). This study was designed to determine whether a fast-growing immunogenic avian sarcoma virus-induced glioma produces primed cytotoxic T lymphocyte precursors during its progression. Lymphocytes from intracerebral glioma-bearing rats generally failed to proliferate in vitro in response to immunization with tumor cells and IL-2 and, when proliferative responses were observed, the lymphocytes were not cytotoxic for glioma cells. However, when the same tumor was growing subcutaneously, lymphocytes proliferated and exhibited glioma-specific cytotoxicity when stimulated in vitro with autologous tumor cells and IL-2. Subcutaneous immunization of intracerebral glioma-bearing rats with tumor cells and adjuvant induced strong cytotoxic T lymphocyte responses. The results demonstrated that, while intracerebral tumor progression itself does not induce an anti-glioma immune response, immune responses to tumor-associated antigens may be induced by systemic immunization of tumor-bearing animals. The results suggest that the immunogenicity of brain tumors is masked by the immunologically privileged status of the brain, not by the induction of generalized immune suppression during tumor progression.     

Molecular characterization and role in T cell activation of staphylococcal enterotoxin A binding to the HLA-DR alpha-chain

Superantigens bind to MHC class II-positive cells and stimulate T lymphocytes expressing specific V beta regions of the TCR. Two distinct regions of staphylococcal enterotoxin A superantigen (SEA) have been shown to affect the binding to MHC class II molecules. Results presented here demonstrate for the first time that the SEA-DR interaction can be affected by mutations on the class II alpha-chain. Furthermore, we have precisely mapped the interaction of the SEA N-terminal domain with the alpha1 domain of HLA-DR. Scatchard analysis using DAP cells transfected with mutant class II molecules showed a role for residue DR alpha K39 in the binding of SEA. Also, complementation experiments using mutant SEA molecules revealed an interaction between SEA residue F47 and position alphaQ18 on an outer loop of HLA-DR. These interactions between SEAF47 and the DR alpha-chain are critical, as they allow the recognition by an otherwise nonreactive V beta1+ T cell hybridoma and induction of tyrosine phosphorylation through the TCR.     

Local expansion of allergen-specific CD30+Th2-type gamma delta T cells in bronchial asthma

BACKGROUND: T lymphocytes infiltrating airways during the allergic immune response play a fundamental role in recruiting other specialized cells, such as eosinophils, by secreting interleukin 5 (IL-5), and promoting local and systemic IgE synthesis by producing IL-4. Whether these presumed allergen-specific T cells are of mucosal or systemic origin is still a matter of conjecture. MATERIALS AND METHODS: Immunophenotype, IL-4 production, and in vitro proliferative response to specific or unrelated allergens were analyzed in the bronchoalveolar lavage (BAL) fluid lymphocyte suspensions obtained from untreated patients with allergic asthma. Healthy subjects and patients affected by pulmonary sarcoidosis, a granulomatous lung disease characterized by infiltrating Th1 CD4+ lymphocytes, served as controls. RESULTS: The proportions of gamma delta T lymphocytes, mostly CD4+ or CD4- (-)CD8-, was higher in asthmatic subjects than in controls (p < 0.05). Most BAL gamma delta CD4+ lymphocytes of asthmatic patients displayed the T cell receptor (TCR)-gamma delta V delta 1 chain. While CD30 antigen coexpression on the surface of BAL alpha beta(+) T lymphocytes was low (ranging from 5 to 12%), about half of pulmonary gamma delta T cells coexpressed it. These cells produced IL-4 and negligible amounts of interferon-gamma (IFN gamma), and proliferated in vitro in response to purified specific but not unrelated allergens. In contrast, control or sarcoidosis gamma delta T cells never displayed the CD30 surface molecule or produced significant quantities of IL-4. CONCLUSIONS: These findings not only confirm our previous hypothesis that the allergen-specific Th2-type lymphocytes found in the lungs of asthmatic patients are gamma delta T cells belonging to airway mucosal immunocytes, but also strongly support the notion that asthma is a local rather than a systemic disease.     

Peripheral clonal deletion of superantigen-reactive T cells is enhanced by cortisone

The T cell receptor (TcR) V beta-specific expansion, deletion and induction of nonresponsiveness among murine T cells responding to superantigens in the periphery has been well characterized. Here we demonstrate that clonal deletion of staphylococcal enterotoxin (SE) B-reactive V beta 8.2+ cells can be significantly increased when mice are injected with hydrocortisone (HC) following superantigen stimulation in vivo. The induced sensitivity to HC persists for at least 30 days after SEB injection, making it unlikely that proliferating cells were uniquely responsible for the enhanced deletion. Superantigen-induced HC sensitivity was a general phenomenon and could also be observed among V beta 11+ cells after the injection of SEA. Experiments conducted on thymectomized mice indicated that HC-sensitive, SEB-responsive cells could not be accounted for by rapidly produced, immature lymphocytes recently exported from the thymus. Further, V beta 8.1+ peripheral lymphocytes from TcR transgenic mice expressing the Mls-1a superantigen were sensitive to HC. These results imply that the majority of cells remaining after superantigen-induced clonal expansion and deletion in vivo have indeed reacted with the superantigen. Implications for differential superantigen recognition by T cells expressing the same TcR V beta domain, perhaps due to a significant V alpha contribution to the interaction in vivo, are discussed.     

Importance of cyclophosphamide-induced bystander effect on T cells for a successful tumor eradication in response to adoptive immunotherapy in mice

Cyclophosphamide (CTX) increases the antitumor effectiveness of adoptive immunotherapy in mice, and combined immunotherapy regimens are now used in some clinical trials. However, the mechanisms underlying the synergistic antitumor responses are still unclear. The purpose of this study was (a) to evaluate the antitumor response to CTX and adoptive immunotherapy in mice bearing four different syngeneic tumors (two responsive in vivo to CTX and two resistant); and (b) to define the mechanism(s) of the CTX-immunotherapy synergism. Tumor-bearing DBA/2 mice were treated with a single injection of CTX followed by an intravenous infusion of tumor-immune spleen cells. In all the four tumor models, a single CTX injection resulted in an impressive antitumor response to the subsequent injection of spleen cells from mice immunized with homologous tumor cells independently of the in vivo response to CTX alone. Detailed analysis of the antitumor mechanisms in mice transplanted with metastatic Friend leukemia cells revealed that (a) the effectiveness of this combined therapy was dependent neither on the CTX-induced reduction of tumor burden nor on CTX-induced inhibition of some putative tumor-induced suppressor cells; (b) the CTX/immune cells' regimen strongly protected the mice from subsequent injection of FLC, provided the animals were also preinoculated with inactivated homologous tumor together with the immune spleen cells; (c) CD4(+) T immune lymphocytes were the major cell type responsible for the antitumor activity; (d) the combined therapy was ineffective in mice treated with antiasialo-GM1 or anti-IFN-alpha/beta antibodies; (e) spleen and/ or bone marrow cells from CTX-treated mice produced soluble factors that assisted in proliferation of the spleen cells. Altogether, these results indicate that CTX acts via bystander effects, possibly through production of T cell growth factors occurring during the rebound events after drug administration, which may sustain the proliferation, survival, and activity of the transferred immune T lymphocytes. Thus, our findings indicate the need for reappraisal of the mechanisms underlying the synergistic effects of CTX and adoptive immunotherapy, and may provide new insights into the definition of new and more effective strategies with chemotherapy and adoptive immunotherapy for cancer patients.     

Myocardial and forearm blood flow reserve in mild-moderate essential hypertensive patients

Interleukin-2 (IL-2) gene therapy alone and in combination with the herpes thymidine kinase gene (tk) was used to evaluate immunological responses and antitumor effects in head and neck cancer. Established floor of mouth squamous cell carcinomas in C3H/HeJ mice were directly injected with recombinant adenoviral vectors carrying both therapeutic and control genes. One week after adenoviral gene transfer, only the animals treated with combination IL-2+tk or tk alone demonstrated significant tumor regression. Residual tumors were harvested for microscopic evaluation and immunohistochemistry staining, which revealed a predominance of CD8+ lymphocytes in the tumor beds of the animals treated with IL-2. To evaluate the systemic immune effects of IL-2, animals treated with single or combination gene therapy received a second site challenge with parental tumor cells or a heterologous but syngeneic sarcoma cell line. Mice treated with combination IL-2 and tk demonstrated a protective systemic immunity specific to the parental tumor cell line, whereas no systemic immune response was evident in mice receiving IL-2 alone. In a separate experiment, a range of concentrations of the adenovirus IL-2 vector were used to treat established tumors. Even with the maximal single-dose adenovirus concentration, IL-2 alone was ineffective as a single therapy. These results support the use of adenovirus-mediated gene transfer of IL-2 as an effective immunotherapy when used adjuvantly with the tk "suicide gene".     

Interleukin 1 beta synergises with interleukin 2 in the outgrowth of autologous tumour-reactive CD8+ effectors

Using peritoneal fluid or pleural effusion obtained from 20 patients with lung, ovarian or metastatic breast cancer, we separated tumour cells from malignant effusion-associated mononuclear cells (MEMNCs) using discontinuous Ficoll-Hypaque density gradients. CD3+ T lymphocytes represented the main population of MEMNCs. The mean +/- s.d. CD4/CD8 ratio of MEMNC suspensions was 1.18 +/- 0.40. MEMNCs proliferated and expanded in vitro with human interleukin 2 (IL-2) either as CD3+ CD8+ cells or as CD3+ CD4+ cells or as mixed populations of CD8+ and CD4+ cells. Preferential cytolytic activity against autologous tumour cells was demonstrated in IL-2-activated MEMNC cultures with excess CD3+ CD8+ cells. In contrast, effectors derived from IL-2-activated cultures with excess CD3+ CD4+ cells lysed both autologous and allogeneic tumour target cells. The addition on day 0 of interleukin 1 beta (IL-1 beta) to MEMNCs cultured in the presence of IL-2 was effective in promoting the growth of CD3+ CD8+ cells and augmenting the cytotoxicity against autologous tumour. Simultaneously, the production of gamma-interferon (IFN-gamma) was increased in these cultures. This is the first report suggesting that IL-1 beta synergises with IL-2 to induce autologous tumour-specific CD8+ cytotoxic T lymphocytes (CTLs) within the MEMNC population. Selective enrichment in T-cell subsets by IL-1 beta may be useful in cellular adoptive immunotherapy using cells isolated from malignant effusions.     

Long-lived and transferable tumor immunity in mice after targeted interleukin-2 therapy

A major goal of tumor immunotherapy is the induction of tumor-specific T cell responses that are effective in eradicating disseminated tumor, as well as mounting a persistent tumor-protective immunity. We demonstrate here that a genetically engineered fusion protein consisting of human/mouse chimeric anti-ganglioside GD2 antibody and human interleukin-2 is able to induce eradication of established B78-D14 melanoma metastases in immunocompetent syngeneic C57BL/6J mice. This therapeutic effect is mediated by host immune cells, particularly CD8+ T cells and is associated with the induction of a long-lived immunity preventing tumor growth in the majority of animals when challenged up to four months later with B78-D14 cells. This effect was tumor-specific, since no cross-protection against syngeneic, ganglioside GD2+ EL-4 thymoma cells was observed. Furthermore, this tumor-specific protection can be transmitted horizontally to naive, syngeneic SCID mice by passive transfer of CD8+ T lymphocytes derived from immune animals. These results suggest that antibody-targeted delivery of cytokines provides a means to elicit effective immune responses against established tumors in the immunotherapy of neoplastic disease.