SEARCH · Search PubMed
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
The temperature-induced expression vector pHZ01 with lambda PRPL promoter for the efficient expression of human-mouse chimeric Fab was constructed. Three kinds of chimeric Fab were expressed in E. coli: anti-prostate specific antigen (PSA) chimeric Fab, anti-lysozyme (HEL) chimeric Fab, and anti-tetanus toxoid (TT) chimeric Fab. All the soluble chimeric Fabs expressed showed specific antigen-binding activities.
BACKGROUND AND OBJECTIVE: Allogeneic bone marrow transplantation (BMT) is the most common treatment for young patients with severe aplastic anemia (SAA). Late graft failure represents one of the possible unfavorable outcomes in this setting. Mixed chimerism might represent a risk factor for late graft failure. We examined this relationship by studying chimerism in long-term survivor SAA patients after allogeneic BMT. METHODS: We analyzed long-term hematopoietic chimerism in 15 patients who received BMTs for SAA: 9 with an irradiation-based conditioning regimen and 6 with ATG. We used a PCR method targeting VNTR loci. Sensitivity of the technique ranged between 0.5 and 1.5%. RESULTS: All patients conditioned with radiation-based schemes showed complete donor chimerism. Conversely, out of six patients who received cyclophosphamide and ATG as a conditioning regimen, only one of them had late graft failure (day +168). In this patient, durable mixed chimera status was first detected two months after BMT. INTERPRETATION AND CONCLUSIONS: Our results suggest that in long-term survivors of SAA after BMT there is almost always complete donor chimerism in both irradiated and ATG-conditioned recipients. Mixed chimerism might predict graft failure in these patients.
BACKGROUND: Mixed bone marrow chimerism reliably produces donor-specific transplantation tolerance for a variety of solid organ and cellular grafts. We used a rat heterotopic tracheal transplant model for chronic rejection to investigate whether mixed chimerism could successfully prevent obstructive airway disease. METHODS: Mixed allogeneic chimeras were prepared by reconstituting lethally irradiated Wistar-Furth (WF) recipients with a mixture of 5 x 10(6) T-cell-depleted syngeneic (WF) and 100 x 10(6) T-cell-depleted allogeneic (ACI) bone marrow cells (ACI + WF --> WF). Mixed chimerism was present in all animals 28 days after bone marrow transplantation. Donor-specific, syngeneic, or major histocompatibility complex (MHC)-disparate allogeneic tracheas were implanted in recipient's omentum and removed for histologic analysis 30 to 150 days after transplantation. RESULTS: At 30 days after implantation, median luminal obstruction grades (0=none, 4=complete) of syngeneic and allogeneic tracheas were 0 and 4, respectively. Donor-specific (ACI) tracheas implanted in chimeric (ACI + WF --> WF) recipients were remarkably free of obstruction (median luminal obstruction grade=0 at 150 days) and had excellent preservation of respiratory epithelium. Third-party F344 tracheas implanted in chimeric recipients developed progressive luminal obstruction (grade 2 at 30 days, grade 3 at 90 days). CONCLUSIONS: Mixed allogeneic chimerism induces donor-specific tolerance and prevents development of the characteristic fibroproliferative obstructive lesion of bronchiolitis obliterans in a rat heterotopic tracheal transplant model. Excellent preservation of tracheal structure and morphology was achieved across major and minor histocompatibility barriers.
BACKGROUND: Thoracic organ transplantation remains limited by the reciprocal problems of rejection and the toxicities of nonspecific immunosuppression. Mixed bone marrow chimerism reliably produces donor-specific transplantation tolerance without immunosuppressive drugs. We have previously described a nonmyeloablative conditioning regimen based on recipient treatment with antilymphocyte serum, tacrolimus, and low-dose total-body irradiation that yields long-term multilineage allogeneic bone marrow chimerism in the rat. We have now investigated whether mixed bone marrow chimerism that arises from this partial conditioning strategy produces permanent acceptance of donor-specific cardiac allografts. METHODS AND RESULTS: Mixed allogeneic chimeras (ACI-->WF) were prepared by treating Wistar Furth recipients with a single dose of antilymphocyte serum 5 days before bone marrow transplantation and tacrolimus 1 mg/kg/d from days -1 to 10. Five hundred cGy total-body irradiation was administered immediately before infusion of 1 x 10(8) donor (ACI) T-cell depleted marrow cells. All recipients were chimeric, with a mean level of donor chimerism = 26.3 +/- 3.5%. Chimeras underwent heterotopic cardiac transplantation 4 weeks after bone marrow transplantation. All donor-specific (ACI) grafts were permanently accepted (follow-up, 230 to 360 days). Third-party grafts were rapidly rejected. Histology of long-surviving donor-specific grafts was without evidence of acute or chronic rejection. Second-set donor-specific skin grafts transplanted to chimeras 135 days after heart transplantation showed long-term survival (> 130 days), whereas third-party skin grafts were rapidly rejected. Mixed lymphocyte reaction demonstrated in vitro donor-specific hyporeactivity. CONCLUSIONS: A tacrolimus-based nonmyeloablative recipient conditioning regimen produces mixed bone marrow chimerism and donor-specific tolerance to cardiac allografts in the rat.
The establishment of a high-level of chimerism may be the most stable strategy for donor-specific tolerance. The purpose of this study was to evaluate the efficacy of a new protocol using cyclophosphamide (CYP) and granulocyte colony-stimulation factor (G-CSF) to induce high-level chimerism following rat whole-limb allotransplantation. Seventy-three whole-limb allotransplants from LacZ transgenic rats to LEW rats were performed. CYP was injected at day 2, and G-CSF was given from day 0 to 3. Nontreated limb allografts were rejected after 4.2 days. In FK506-treated group for 28 days, the survival time was prolonged to 64 days. In the group treated with CYP/G-CSF, limb allografts were rejected after 5.4 days and 5 of 15 recipients showed acute lethal graft-versus-host disease (GVHD). Polymerase chain reaction (PCR) study showed a high level of chimerism even within 1 week after transplantation. Fourteen of 30 recipients given CYP/G-CSF/FK506 died within 2 weeks. The limb survival was significantly prolonged, however, with three grafts surviving more than 300 days. Seven recipients (24%) showed chronic GVHD. A high-level of chimerism was maintained when limb allografts were not rejected by recipients. Limb allografting could function as a vascularized carrier for bone marrow transplantation, provide a continuous source of donor cells and contribute to a high level of chimerism in the recipient. Pretransplant CYP followed by G-CSF and FK506 treatment significantly prolonged the survival of limb allografts but frequently caused chronic GVHD in the recipients.
For decades, it has been widely accepted that the heart is a terminally differentiated organ that is unable to regenerate. Studies of recipients of hearts donated by other humans have shed light on the regenerative potential of the human heart. Investigators have been able to trace the Y chromosome by fluorescence in situ hybridization or polymerase chain reaction, or both, in sex-mismatched heart recipients. Cardiac chimerism has been reported, with concentrations of chimeric cells ranging from 0.04% to 10.0%. Cardiac chimerism after bone marrow or progenitor cell transplantation has also been reported to a low extent (approximately 0.20%), suggesting that a fraction of the extracardiac cells that colonize the myocardium are of bone marrow origin. Cardiac chimerism after pregnancy with male offspring (fetal cell microchimerism) has also been demonstrated. Cells of fetal origin have been shown to be capable of differentiating into myocardial cells. Collectively, we show that chimerism studies provide a proof of concept of a process that it is likely to be part of normal cardiac homeostasis in humans but apparently insufficient for cardiac repair in diseased hearts.
This study used quantitative PCR in the murine model to compare the ability of a limb allograft vs. a comparable dose of marrow suspension to induce chimerism. Female C57Bl/6 mice received a vascularized hindlimb allograft, a comparable dose of 5 x 10 (6) donor bone marrow cells, or a standard dose (20 x 10 (6)) of marrow suspension from male Balb/c donors. All recipients were treated with a regimen based on CD40 costimulation blockade and T cell depletion. Y chromosome-specific quantitative PCR was used to measure chimerism. Most recipients of limb allografts demonstrated low levels of chimerism after 1 week (3/4) and 1 month (3/4). Most recipients of 5 x 10 (6) marrow cells had low levels of chimerism at 1 week (4/6) and only 1/5 after 1 month. All recipients of 20 x 10 (6) cells except one demonstrated either low or high levels of chimerism after 1 week (5/5) and 1 month (5/6). The marrow component of a limb allograft is thus more effective at inducing microchimerism compared to a comparable dose of bone marrow suspension.
Mixed hematopoietic chimerism usually carries with it the tolerance to any other tissue from the same donor. Consequently, the establishment of a sustained chimerism may allow long-term acceptance of transplanted organs without immunosuppression. We report a girl with refractory severe aplastic anemia who developed low recipient level hematopoietic chimerism following transplantation of maternal highly purified CD34+ cells without prophylactic immunosuppression. Renal thrombotic microangiopathy led to chronic renal failure and she received skin allografts from her mother in view of a future kidney donation. The maternal skin grafts were accepted without immunosuppression and the hematopoietic chimerism remained stable. Skin transplantation may be a helpful and easily applicable tool to monitor donor-related tolerance in hematopoietic chimerism clinically. It should contribute to minimize the risks of subsequent solid organ transplantation from the same donor without immunosuppression.
BACKGROUND: Chimerism is the presence of two or more genetically distinct cell populations in one organism. STUDY DESIGN AND METHODS: We report the identification of dispermic chimerism in a 19-year-old female volunteer blood donor. During routine ABO blood grouping strong reactions of the blood donors red blood cells (RBCs) with anti-A reagents and mixed-field reactions with anti-B reagents were observed, while serum-testing showed the absence of anti-A and anti-B antibodies. AB0 blood group genotyping, HLA-typing and microsatellite analysis were performed using blood-samples, buccal mucosa and fibroblasts of the blood-donor and blood-samples of her parents. RESULTS: AB0 blood group genotyping showed three ABO blood group alleles (0(1), A(2) and B) in the DNA-samples of the blood-donor. The evidence of chimerism was supported by the detection of three alleles for the HLA-A and HLA-DRB1 loci. Microsatellite analysis with ten markers revealed three alleles for loci D7S821 and D19S412. All studies carried out, the third allele was always of paternal origin. CONCLISION: The results suggested a case of a human dispermic chimerism. Our proposed explanation for the development of chimerism in the reported case is the fertilization of an oocyte and the corresponding second polar body by two different sperms.
The aim of this study was to analyze the hematopoietic chimerism after non-myeloablative allogeneic peripheral blood stem cell transplantation (NAPBSCT). 28 patients received NAPBSCT were evaluated. The conditioning regimen included FBC (fludarabine, busulphan, cyclophosphamide) +/- Ara-C. Peripheral blood was collected before and after transplantation in different periods. Semi-quantitative assessment of hematopoietic chimerism was performed by short tandem repeat-polymerase chain reaction (STR-PCR), polyacrylamide gel electrophoresis (PAGE) and silver staining, and analyzed by Image Analysis System. The results showed that on day 30 after transplantation, one patient failed to engraft, but 22 cases formed complete chimerism (CC) and 5 cases were of mixed chimerism. On day 7 after transplantation, the average percentage of donor cells was 74.71%. The time of dominance of the donor-specific allelic pattern preceded the recovery time of neutrophils and platelets. The incidence of aGVHD in group CC was significantly higher than that in group MC (P < 0.05). There was no significant difference in the incidence of cGVHD and disease relapse between group CC and group MC (P > 0.05). One patient relapsed in CC status without a transitional stage of MC. One patient with MC rejected grafts in early stage. 3 patients with MC transferred to CC and got complete remission after early implementation of therapy. It is concluded that sequential and quantitative detection of chimerism may be of great value to evaluate engraftment and to predict graft rejection, disease relapse and GVHD. Furthermore, it may provide a basis for early intervention treatment in the related complications.
To determine the clonality and cellular origin of colon pre-neoplastic and neoplastic lesions, C3H/HeN<-->BALB/c chimeric mice treated with 1,2-dimethylhydrazine (DMH) were investigated immunohistochemically using a specific antibody to C3H strain-specific antigen (CSA) enabling immunohistochemical discrimination of C3H cells in histological sections of chimeric mouse tissues. To confirm the results of immunostaining, simple sequence length polymorphism (SSLP) analysis was performed on DNA samples extracted from histological sections of adenocarcinomas. C3H/HeN<-->BALB/c chimeric mice were produced by an aggregation procedure and together with BALB/c and C3H/HeN animals were given weekly s.c. injections of 20 mg/kg body weight DMH for up to 20 weeks. At weeks 20 and 35 animals were killed and autopsied. In normal colonic mucosa of the chimeras, each gland was composed entirely of either CSA-positive or -negative cells and no mixed glands were found. Cells of all focal atypias in chimeric mice were, in each case, homogeneous for one or another of the parental types. Of 91 adenomas in chimeric mice, only one comprised both types of cell. Among 119 adenocarcinomas, 12 contained cells of both parental types. In these tumors, however, the 2 phenotypes were not mixed together at random but arranged in discrete areas, with intermingling limited to the junctions. SSLP analysis demonstrated DNAs extracted from CSA-positive and -negative tumors to exhibit the polymorphic patterns of C3H and BALB/c, respectively, while mixed CSA-positive and -negative tumors showed mixtures of both polymorphic DNA types.
B cells that are destined to secrete IgE express a membrane-bound form of IgE (mIgE) on their cell surface. Thus, elimination of such mIgE-positive cells should result in the suppression of IgE production, thereby alleviating the symptoms of IgE-mediated allergy. In this study, we examined, in a model system, whether IgE-specific effector T cells can be used specifically to eradicate IgE-producing B cells. To this end, we endowed T cells with anti-IgE specificity using chimeric T cell receptors (cTCR) containing the variable region domain (Fv) of the 84.1c non-anaphylactic anti-mouse IgE monoclonal antibody (mAb). Two configurations of chimeric receptor were used: in the first, we combined the heavy and light variable region chains of 84.1c with the constant (C) regions of the TCR alpha and beta chains. The second construct consisted of a chimeric single-chain receptor (scFvR), composed of a single-chain Fv region of the 84.1c antibody and the C beta domain of the TCR. Following transfection of the cTCR or the scFvR genes into the murine MD.45 cytotoxic T cell hybridoma or the Jurkat human T cell line, functional expression of IgE-specific chimeric receptors was detected on the cell surface. The transfected cells secreted interleukin-2 upon stimulation with immobilized IgE or fixed IgE-producing hybridoma cells. Moreover, cytotoxic T cell hybridomas expressing the chimeric receptor genes specifically eliminated IgE-secreting B cells in vitro, resulting in isotype-specific suppression of IgE production.
Rats from the allotype-marked PVG-RT7b and PVG-RT1u-RT7b strains were injected at birth with semi-allogenic F1 bone marrow (BM) cells from athymic nude rats (PVG-rnu/rnu x PVG-RT1u-rnu/rnu) to induce neonatal tolerance. As adults, 97% of the animals accepted donor-specific allogeneic skin grafts and a majority (65%) of rats were chimeric, expressing the major histocompatibility complex class I and allotype marker of the donor strain. Similar results were obtained when PVG-RT1u-RT7b rats were injected at birth with fully allogeneic PVG-rnu/rnu nude BM cells: as adults, 94% accepted donor-specific skin allografts and 76% of recipients were chimeric. Donor derived CD4 T cells, CD8 T cells and B cells were found in low numbers (less than 2%) in peripheral blood of rats made tolerant by F1 BM cells. A large proportion of T cells bore the phenotype of recent thymic emigrants, suggesting that they were newly produced. All the evidence was consistent with clonal deletion tolerance, induced centrally within the thymus. The thymus was chimeric and thymocytes failed to respond in vitro to alloantigens of the donor-specific haplotype; donor-specific skin allografts survived indefinitely on athymic nude recipients reconstituted with CD4+CD8- thymocytes or peripheral CD4 T cells from tolerant animals. The chimeric state was interesting, since the PVG and PVG-RT1u rat strains contain a natural killer (NK) cell system that rapidly eliminates (within 24 h) intravenously injected allogeneic or semi-allogeneic lymphocytes--a phenomenon known as allogeneic lymphocyte cytotoxicity or ALC. When neonatal tolerant rats were tested, the ALC index (a measure of cell killing) was unchanged in nonchimeric tolerant rats and significantly altered (reduced killing), but not abolished in chimeric animals. Hence, the injection of allogeneic BM cells which induced specific tolerance in the T cell population failed to tolerize the NK cell system, allowing the constant killing of newly produced donor-derived lymphocytes and putting at risk the very survival of the allogenic BM cells. This has interesting implications for clinical transplantation.
Mice chimeric for embryonic stem (ES) cells have not always successfully produced ES-derived offspring. Here we show that the male gametes from ES cells could be selected in male chimeric mice testes by labeling donor ES cells or host blastocytes with GFP. Male GFP-expressing ES-derived germ cells occurred as colonies in the chimeric testes, where the seminiferous tubules were separated into green and non-green regions. When mature spermatozoa from green tubules were used for microinsemination, GFP-expressing offspring were efficiently obtained. Using a reverse study, we also obtained ES-derived progeny from GFP-negative ES cells in GFP-labeled host chimeras. Furthermore, we showed this approach could be accelerated by using round spermatids from the testes of 20-day-old chimeric mice. Thus, this technique allowed us to generate the ES cell-derived progeny even from the low contributed chimeric mice, which cannot produce ES-origin offspring by natural mating.
Only humans and chimpanzees are fully permissive for replication of hepatitis C virus (HCV), an important cause of liver cirrhosis and cancer worldwide. The absence of suitable animal models limits opportunities for in vivo evaluation of candidate hepatitis C therapeutics and slows progress in the field. Here, we describe a chimeric virus derived from GB virus B (GBV-B), an unclassified hepatotropic member of the family Flaviviridae that is closely related to HCV and infects tamarins (Saguinus sp.), in which a functionally important HCV regulatory sequence replaced an analogous sequence in the 5' nontranslated region (5'NTR) of the GBV-B genome. The transplanted sequence comprised domain III of the internal ribosome entry site (IRES), which directly binds the 40S ribosome subunit and is a target for candidate therapeutics. The chimeric 5'NTR retained ribosome binding activity and was competent in directing protein translation both in cell-free translation reactions and in transfected primary tamarin hepatocyte cultures. Virus rescued from the chimeric RNA replicated in the liver of tamarins, causing biochemical and histopathological changes typical of viral hepatitis. However, adaptive mutations were required elsewhere in the genome for efficient replication. Virus was not rescued from other, translationally competent, chimeric RNAs in which domain II of the IRES was exchanged. Thus, the 5'NTR appears to contain virus-specific replication signals that interact with other sites within the viral genome or with viral proteins. In conclusion, such novel chimeric flaviviruses offer opportunities for new insights into HCV replication mechanisms, while potentially facilitating the evaluation of candidate therapeutics in vivo.
The t(11;22)(q24;q12) and t(21;22)(q22;q12) are specific chromosomal translocations found in the Ewing family of tumors including ES, PNET and Askin tumors. In these translocations, the amino-terminal portion of the EWS gene located in 22q12 fuses to the carboxyl-terminal portion of the FLI-1 gene located in 11q24 or the ERG gene located in 21q22, which belong to the ets oncogene superfamily of transcription activators. We investigated the chimeric mRNAs of 15 ESs (7 cell lines and 8 tumor samples) and 7 PNETs (3 cell lines and 4 tumor samples) using the RT-PCR method and sequencing. We detected 2 types of EWS-ERG chimeric mRNA in 2 ES cell lines and 1 PNET tumor sample in addition to 4 types of EWS-FLI-1 chimeric mRNA in 11 ESs (4 cell lines and 7 tumor samples) and 4 PNETs (2 cell lines and 2 tumor samples). There seemed to be no association between the type of chimeric mRNA and clinical features such as sex, age, primary site and histopathology of the patients. All of the chimeric mRNAs are generated from in-frame junctions and are thought to encode fusion proteins that may be the molecular mechanism involved in the Ewing family of tumors.
BACKGROUND: Inhibition of intercellular adhesion molecule-1 (ICAM-1) expression can ameliorate the inflammation induced by ischemia-reperfusion injury (IRI) in animal models. However, current strategies to reduce ICAM-1 expression have been limited by the lack of stability, poor specificity, and the transient nature of synthesized regulatory molecules (antisense/ribozyme). METHODS: A chimeric expression vector was generated by fusing a ribozyme targeting sequence against ICAM-1 to stabilizing stem-loop structures and nuclear localization signals that are components of endogenous U1 small nuclear RNA. Oligonucleotide scanning was used to predict accessible sites for targeting within the rat ICAM-1 transcript. Efficacy of the chimeric ribozyme vector was tested by transfection of rat aortic endothelial (RAE) cells (in vitro) and intraportal delivery in a rat hepatic IRI model (in vivo). RESULTS: Transfection of RAE cells with the chimeric ribozyme vector produced potent and specific inhibition of ICAM-1 mRNA and protein levels by >65%. This reduction in ICAM-1 expression was accompanied by a proportional decrease in neutrophil adhesion to RAE cells. In vivo intraportal delivery of the chimeric targeting vector to rats sustaining hepatic IRI produced a marked reduction in ICAM-1 expression on liver endothelium after reperfusion. CONCLUSIONS: A chimeric ribozyme vector effectively inhibited ICAM-1 expression in vascular endothelial cells and in rat liver following IRI, demonstrating a novel gene targeting technique that may be ideally suited to clinical applications aimed at ameliorating IRI.
Chimeric receptors that redirect effector cell function to tumor cells or virus-infected cells have received much attention. Given the high affinity of Fc(epsilon)RI for immunoglobulin E (IgE) and low serum IgE levels, redirection of effector cells using Fc(epsilon) receptor may provide a novel, versatile, and effective anti-tumor strategy. We have used a mouse perforin 5'-promoter to express a single-chain human Fc(epsilon) receptor in the mouse cytotoxic T lymphocyte cell line, CTLL-R8. Upon ligation of the chimeric Fc(epsilon) receptors by IgE, a signal for effector function is transmitted via the intracellular domain of CD3zeta. Selection in G418-containing medium produced CTLLR8 transfectant clones that: (1) expressed chimeric Fc(epsilon) receptor as determined by flow cytometry; (2) bound human IgE antibodies with high affinity as determined by Scatchard analysis; (3) specifically rosetted IgE-coated SRBC; (4) lysed target cells in IgE-mediated ADCC and reverse ADCC assays; and (5) retarded tumor growth in a Winn assay. Therefore these chimeric Fc(epsilon) receptors can effectively redirect cytotoxicity to tumor cells. Future efforts will assess the versatility and efficacy of these IgE-binding chimeric receptors to redirect killer cell function in animal tumor models.