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Vaccination Protocols (vaccination + protocol)
Selected AbstractsDNA vaccine encoding endosome-targeted human papillomavirus type,16 E7,protein generates CD4+ T cell-dependent protectionEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 2 2007Jean-Marc Brulet Abstract Human papillomavirus type,16 is commonly implicated in cervical cancers. The viral genome encodes potential targets like the oncoprotein,E7, expressed in transformed cells but thought to represent a poorly immunogenic antigen. We describe in this work a DNA-based vaccination protocol aimed at inducing an efficient anti-E7 immune response in vivo. Plasmids allowing the expression of the E7,protein in distinct cellular compartments were generated and assayed in an in vivo model of tumor growth. Our data demonstrate that mice vaccinated with a plasmid encoding for an E7,protein fused to a domain of the MHC class,II-associated invariant chain (IiE7) were protected against tumor challenge. Mice immunized against an ubiquitinated form of E7 (Ub(Ala)E7) failed to control tumor growth. Protection induced by IiE7 was correlated with the development of CD8+ CTL and required the presence of CD4+ cells. In vitro studies confirmed that the IiE7 fusion protein was expressed at high levels in the endosomal compartment of transfected cells, while the natural and the ubiquitin-modified form of E7 were mainly nuclear. The present study suggests that an efficient anti-tumor response can be induced in vivo by DNA constructs encoding for E7,protein forms localizing at the endosomal compartment. See accompanying commentary: http://dx.doi.org/10.1002/eji.200636233 [source] Lack of dendritic cell maturation by the plant toxin ricinEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 8 2004Daniel Abstract Several bacterial toxins either promote or inhibit the maturation of human monocyte-derived DC. Since the potent plant toxin ricin exploits the same cell entry pathway used by these bacterial toxins and shares identical catalytic activity with some of them, we have studied the capacity of ricin to induce DC maturation in vitro. Here, we show that in contrast to the bacterial proteins, ricin neither induces DC maturation nor interferes with LPS-induced DC maturation. There is no correlation between the absence of DC maturation and ricin dysfunction. Indeed, some of the ricin variants retain significant ribotoxicity and catalytic activity. We have extended these observations to ebulin-1, suggesting that this may be a general characteristic of plant-derived cytotoxic ribosome-inactivating toxins. The human immune system may therefore have evolved to recognize and rapidly respond to the bacterial proteins, whilst being less responsive to the equivalent plant cytotoxins. Understanding the effect of ricin on professional APC may provide insights into the generation of an anti-ricin vaccine and into the use of inactivated ricin A,chains as delivery vectors as part of a vaccination protocol. [source] Hepatitis B vaccination in haemodialysis patients: A randomized clinical trialNEPHROLOGY, Issue 3 2009MARILENE BOCK SUMMARY Aim: A short vaccination protocol against hepatitis B was compared to the standard approach in patients under haemodialysis who were primarily non-responsive to the vaccine. Methods: This randomized, controlled open trial included 51 chronic haemodialysis subjects previously vaccinated against hepatitis B and with anti-HBs levels of less than 10 IU/mol/L. Twenty-six patients received 20 µg i.m. once a week for 8 weeks (short protocol) and 25 subjects three doses of 40 µg i.m. at months 0, 1 and 6 (standard protocol). Clinical and laboratory data were compared between responders and non-responders. A logistic regression model included selected parameters to assess risk factors for non-seroconversion. Results: Seroconversion rates to vaccine at 2 months were 80% and 78% in the short and standard protocol groups, respectively (P = 0.99). Median of anti-HBs levels were similar up to 6 months of follow up, but patients in the standard protocol showed a trend to higher anti-HBs in month 3 and a more steady decline in antibody titres. Non-responders were older, had longer duration of dialysis and a higher prevalence of a prior renal transplant and hepatitis C. In multivariate analysis, only advanced age and hepatitis C remained independently associated with non-responsiveness to vaccination. Conclusion: In haemodialysis patients, a short vaccination protocol against hepatitis B did not provide any benefit compared to the standard approach with respect to peak anti-HBs titres or a higher rate of seroprotection at the end of follow up. Other strategies to increase seroconversion rates should be explored, especially in the elderly and in patients with hepatitis C. [source] ,-Amyloid immunization approaches for Alzheimer's diseaseDRUG DEVELOPMENT RESEARCH, Issue 2 2002Bruno P. Imbimbo Abstract Alzheimer's disease (AD) represents the third leading cause of death in the U.S. and the leading cause of dementia in the elderly population. Until recently, there was little hope of efficiently combating this devastating disease. The deposition of ,-amyloid (A,) is the major pathological hallmark of AD brains. Genetic, biochemical, and pharmacological evidence support the hypothesis that A, plays a key role in the development of the disease. Thus, in the last 5 years a number of pharmacological strategies have been developed to interfere with the A, cascade. The most revolutionary of these approaches was proposed in 1999 by scientists at Elan Pharmaceuticals, which immunized against A, transgenic mice with spontaneously developing A, pathology. The immunization was achieved by subcutaneous injections of a preaggregated form of the synthetic human 42-amino acid A, emulsified with Freund's adjuvant, an immune stimulant. The vaccination caused a near complete inhibition of A, plaque formation in younger animals and a marked reduction of the A, burden in older animals. The effects on A, plaques were accompanied by a reduction of A,-associated astrogliosis and neuritic dystrophy. These results were later confirmed by other groups with similar vaccination protocols, which also demonstrated that the A, immunization of transgenic animals normalize or reduce the cognitive impairment associated with A, pathology. Interestingly, effective removal of brain A, plaques was also obtained by peripherally administering A, antibodies. The mechanism with which the vaccine increases A, clearance is not fully understood. Centrally, the vaccine appears to activate A, phagocytosis by microglial monocytes. Peripherally, serum A, antibodies bind and sequester A,, thus altering its equilibrium between CNS and plasma. The dramatic results obtained in animal models of AD raised unprecedented hopes for both a preventive and a curative intervention for this devastating disorder. A vaccine preparation for human use (AN-1792) composed of preaggregated human A,42 peptide and a highly purified saponin derivative (QS-21) was developed by Elan Pharmaceuticals and Wyeth Ayerst and tested in AD patients. Unfortunately, a Phase IIa study aimed at evaluating the safety and immunological activity of AN-1792 in 360 AD patients was discontinued because 15 subjects receiving the vaccine developed serious signs of CNS inflammation. Both central activation of cytotoxic T cells and autoimmune reactions were proposed as potential mechanisms of toxicity. Other therapeutic A, vaccination strategies are being pursued, including immuno-conjugates and monoclonal antibodies. The future of these and other A, immunization approaches depend on a clear understanding of the mechanism of A, clearance and additional insight into the role of inflammation in the AD brain. Drug Dev. Res. 56:150,162, 2002. © 2002 Wiley-Liss, Inc. [source] Assessment of CD8 involvement in T,cell clone avidity by direct measurement of HLA-A2/Mage3 complex density using a high-affinity TCR like monoclonal antibodyEUROPEAN JOURNAL OF IMMUNOLOGY, Issue 10 2005Karine Bernardeau Abstract Peptide affinity for MHC molecules determines the number of MHC/peptide complexes stabilized at the cell surface in in vitro tests or in vaccination protocols. We isolated a high affinity monoclonal antibody specific for the HLA-A2/Mage3 complex that enables an equilibrium binding assay to be performed on T2 cell line loaded with a range of Mage3 peptides. Binding of Mage3 to the HLA-A2 molecule can be modeled by a standard receptor-ligand interaction characterized by an affinity constant. This model enables the measurement of the affinity of other immunogenic peptides for HLA-A2 by a competition test and the calculation of the density of complexes stabilized at the T2 cell surface for all peptide concentrations. Quantification of the HLA-A2/Mage3 complexes at target cell surfaces was used to estimate the number of complexes required to reach cytotoxicity ED50 of human T,cell clones sorted from an unprimed repertoire. We confirm with this antibody the direct relationship between clone avidity and TCR affinity, and the moderate contribution of the CD8 co-receptor in the reinforcement of TCR-MHC/peptide contact. Nevertheless, CD8 plays a critical role in the amplification of the specific signal to establish an efficient T,cell response at low specific complex densities found in physiological situations. [source] Differential CD4+ T-cell memory responses induced by two subsets of human monocyte-derived dendritic cellsIMMUNOLOGY, Issue 3 2007Sandra Bajańa Summary Dendritic cells (DC) are powerful inducers of primary T-cell responses, but their role in secondary responses has not been extensively analysed. Here, we address the role of two DC subsets derived from human CD16+ (16+ mDC) or CD16, (16, mDC) monocytes on the reactivation of memory responses. CD4+ CD45RA, memory T cells were obtained from adult blood donors, and central (TCM) and effector (TEM) memory T cells were isolated by fluorescence-activated cell sorting with anti-CCR7 antibodies. The 16+ mDC and 16, mDC were cocultured with autologous lymphocytes, either unpulsed or loaded with purified protein derivatives of Mycobacterium tuberculosis (PPD) or tetanus toxoid (TT), and were analysed for up to 8 days. Over a range of doses, 16+ mDC drove stronger T-cell proliferative responses against both antigens. Overall, antigen-specific memory cells tended to acquire a phenotype of TEM at later time-points in the culture, whereas cells that had completed fewer cycles of division were similar to TCM. The 16+ mDC induced higher rates of proliferation on both TCM and TEM lymphocytes than 16, mDC. This phenomenon was not related to the ability of both DC to induce CD25 expression on T cells, to lower secretion of interleukin-2, or to raise production of interleukin-10 during T-cell/16, mDC cocultures. The induction of TCM effector capacity in terms of interferon-, production was faster and more pronounced with 16+ mDC, whereas both DC had similar abilities with TEM. In conclusion, these data might reveal new potentials in vaccination protocols with 16+ mDC aimed at inducing strong responses on central memory T cells. [source] Monocyte-derived dendritic cells from HCV-infected patients transduced with an adenovirus expressing NS3 are functional when stimulated with the TLR3 ligand poly(I:C)JOURNAL OF VIRAL HEPATITIS, Issue 11 2008I. Echeverrķa Summary., Dendritic cells (DC) transfected with an adenovirus encoding hepatitis C virus (HCV) NS3 protein (AdNS3) induce potent antiviral immune responses when used to immunize mice. However, in HCV infected patients, controversial results have been reported regarding the functional properties of monocyte-derived DC (MoDC), a cell population commonly used in DC vaccination protocols. Thus, with the aim of future vaccination studies we decided to characterize MoDC from HCV patients transfected with AdNS3 and stimulated with the TLR3 ligand poly(I:C). Phenotypic and functional properties of these cells were compared with those from MoDC obtained from uninfected individuals. PCR analysis showed that HCV RNA was negative in MoDC from patients after the culture period. Also, phenotypic analysis of these cells showed lower expression of CD80, CD86, and CD40, but similar expression of HLA-DR molecules as compared to MoDC from uninfected individuals. Functional assays of MoDC obtained from patients and controls showed a similar ability to activate allogeneic lymphocytes or to produce IL-12 and IL-10, although lower IFN-, levels were produced by cells from HCV patients after poly(I:C) stimulation. Moreover, both groups of MoDC induced similar profiles of IFN-, and IL-5 after stimulation of allogeneic T-cells. Finally, migration assays did not reveal any difference in their ability to respond to CCL21 chemokine. In conclusion, MoDC from HCV patients are functional after transduction with AdNS3 and stimulation with poly(I:C). These findings suggest that these cells may be useful for therapeutic vaccination in chronic HCV infection. [source] Molecular pathological approaches to human tumor immunologyPATHOLOGY INTERNATIONAL, Issue 4 2009Noriyuki Sato Research on human tumor immunology has greatly advanced in the past two decades. Many immunogenic tumor antigens have been identified, and some of these antigens entered in clinical trials. Consequently, it has been shown that these antigens can inhibit tumor growth in patients to some extent, indicating that they act as potent immunogenic therapeutic vaccines in cancer patients with malignancies originating from various tissues. These patients had antigen-specific cytotoxic T-lymphocyte (CTL) responses when assessed on tetramer, enzyme-linked immunospot (ELISPOT), T-cell clonotype and CTL induction efficiency. Thus, it has become clear that human tumor vaccines can evoke clinical and immunological anti-tumor responses in patients. The tumor regression effects of tumor vaccines, however, are generally low, and it is obvious that current vaccination protocols are generally too weak to provide substantial and satisfactory clinical benefits. This means that other drastic and more potent clinical and immunological protocols are required in cancer immunotherapy. To find such efficient protocols the basic immunological and biological properties of cancers must be investigated. In the present review the identification of human tumor antigens recognized on CTL and the clinical trials are introduced. Next, the most recent analysis of human cancer-initiating cell (cancer stem cell)-associated antigens is described. These antigens might be able to act as ,universal, general and fundamental' tumor antigens. Also present is the authors' recent study for increasing cross-presentation efficiency in dendritic cells and subsequent enhancement of human leukocyte antigen (HLA)-class I-restricted peptide antigenicity by using HSP90 and ORP150 molecular chaperones that act as endogenous Toll-like receptor ligands. In addition to the aforementioned manipulation of the positive loop of tumor immunity, it is necessary to regulate and intervene in the negative loop. In particular, the potential of the expression of HLA class I molecule regulation by epigenetic mechanisms will be discussed. Finally, the type of basic and clinical tumor immunology research highly required currently, and in the very near future, are described. [source] | ||||||||||