Biomedical subjects

M Heberer

Publications and source records attributed to M Heberer.

At least 37 records · Page 2Linked to original sources

PubMed2001

The effect of pretreatment with ischaemic preconditioning or cromakalim on perfusion in skeletal muscle during ischaemia-reperfusion injury.

BACKGROUND: Ischaemia-induced damage of skeletal muscle may lead to side effects in orthopaedic and reconstructive surgery where tourniquet ischaemia is applied to ensure a bloodless operative field. In this study we investigated the effect of ischaemia-reperfusion injury with and without preconditioning by studying the skeletal muscle microcirculation. A further aim was to establish whether ischaemic preconditioning or pretreatment with cromakalim, a potassium channel opener reduces ischaemia-reperfusion injury. METHODS: Twenty-eight Wistar rats were randomised into four groups (n=7 per group). Group 1, control with no treatment; Group 2, two and a half hours tourniquet ischaemia followed by two hours of reperfusion to the left hindlimb. Furthermore, we pre-treated two groups prior to the ischaemia-reperfusion period; Group 3 with three short cycles of ischaemia-reperfusion (5'/5') and Group 4 pre treated with cromakalim (100 microg/kg bw). We monitored the gastrocnemius muscle blood flow in vivo. RESULTS: There were no significant changes in the skeletal muscle microcirculation and temperature at the baseline in the four groups (p=0.110). In the ischaemic reperfusion, ischaemia preconditioning and cromakalim groups, the recorded skeletal muscle microcirculation during ischaemia decreased significantly (p<0.001) with respect to the baseline. In Group 2 the microcirculation recovered rapidly after release of the tourniquet, but was significantly lower (37 percent of baseline value, p<0.001) within two hours of reperfusion. In the ischaemia preconditioning group the microcirculation as in the ischaemia-reperfusion group recovered rapidly after release of the tourniquet, although failing to reach the baseline value within two hours of reperfusion. The mean microcirculation value of the left limb was slightly higher than Group 2 but significantly lower compared to the baseline after two hours of reperfusion (p<0.001). The change in the skeletal muscle microcirculation with cromakalim after two hours of reperfusion was not significant when compared to baseline values (p>0.05). The cromakalim group after two hours reperfusion had significantly higher microcirculation values when compared with Groups 2 and 3 (p<0.001). During ischaemia-reperfusion in Groups 2-4, there was no significant alteration in the systemic haemodynamic circulation. CONCLUSIONS: This study supports the hypothesis that cromakalim reduces postischaemic skeletal muscle damage and reperfusion injury.

Animals↗

PubMed2000

Naturally processed and concealed HLA-A2.1-restricted epitopes from tumor-associated antigen tyrosinase-related protein-2.

In this study, a computer-assisted reverse immunology approach was utilized in order to identify potentially antigenic peptides derived from the differentiation antigen TRP-2, a melanosomal protein frequently expressed in melanoma. Among the seven peptides complying with HLA-A2.1-binding motifs, two induced specific CD8(+) cytotoxic T lymphocytes. HLA-A2.1(+) melanoma cells expressing TRP-2 were lysed by clones specific for TRP-2(360-368) (TLDSQVMSL) peptide, thus identifying it as a naturally processed epitope. Other T-cell clones directed against TRP-2(476-484) (VMGTLVALV) were unable to lyse HLA-matched TRP-2(+) cell lines. The role of intracellular proteolytic processing in the generation of this epitope was investigated by transfecting mini-genes encoding the TRP-2(476-484) peptide alone or carrying N- or C-terminal extensions. Specific T-cell clones recognized target cells expressing the cytotoxic T-lymphocyte (CTL)-defined epitope or its C-terminally extended precursor, but failed to recognize cells expressing the N-terminally extended TRP-2(476-484) peptide, suggesting the presence of a negative processing signal (NPS). Regarding C-terminus-flanking regions, mutational analysis indicates that the GLY485 residue plays a key role in the processing of the TRP-2(476-484) epitope. Interestingly, proteasome inhibitors preventing the generation of the MART-1/Melan-A(27-35) immunodominant melanoma tumor-associated antigen (TAA) promoted detectable presentation of TRP-2(476-484) epitope in HLA-A2.1(+) and TRP-2(+) tumor lines, as witnessed by cytokine release by specific T-cell clones.

Acetylcysteine↗

PubMed2000

Identification of genes differentially expressed in melanoma sublines derived from a single surgical specimen characterised by different sensitivity to cytotoxic T-lymphocyte activity.

In this study we used differential display technology in an attempt to obtain an insight into the mechanisms underlying escape of tumour cells to the specific cytotoxic T cell response. A primary tumour cell line and autologous tumour infiltrating lymphocytes were raised from a metastatic melanoma sample (ME15). Upon co-culture of tumour infiltrating lymphocytes with irradiated tumour cells, CTL specific for neoplastic cells were generated and cloned. Using a CTL clone, a cytotoxicity resistant tumour subline (ME15R) was immunoselected. We applied a PCR-based differential display technique to amplify DNA sequences differentially expressed in ME15 sublines sensitive (S) or resistant (R) to specific CTL killing. 10 different sequences whose expression was exclusively detectable in ME15S cells were identified. Five of them matched with known expressed sequence tags encoding products of unidentified function. 2 showed high homology with a mitochondrial mRNA and with the gene encoding the S24 ribosomal protein. Most interestingly, genes coding for glutamine synthetase, TGF-beta-3 and PAX3, a well-characterised transcription factor, were only expressed in ME15S cells. The latter gene was found to be transcribed in all healthy tissues tested, but only in a subgroup of established melanoma cell lines. Taken together, our data underline the relevant potential of differential display technology in the molecular analysis of paired tumour lines endowed with different phenotypic characteristics. Cloning of entire open reading frames and transfection studies are warranted to clarify the role of individual differentially displayed genes in the escape of tumour cells from cellular immune response.

Base Sequence↗

PubMed2000

FLT3 ligand gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens.

Dendritic cells (DC) are professional antigen presenting cells (APC) whose proliferation and functional differentiation can be induced by hematopoietic growth factors including GM-CSF and FLT3 ligand (FL). Colorectal cancers are known to be infiltrated by dendritic cells (DC) and neoplastic cells have been shown to produce GM-CSF. In this work we investigated FLT3 ligand (FL) gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens. Using reverse transcription polymerase chain reaction (RT-PCR), 6 out of 6 established tumor lines were found to express to variable extents FL gene. In 1 of them, SW480, FL immunoreactivity could be observed by taking advantage of specific antibodies. In contrast, soluble FL could not be detected in any culture supernatant. FLT3 receptor (FR) gene was not expressed and exogenous addition to the cultures of recombinant FL (rFL) did not affect the proliferation of the tumor lines. FL gene expression was investigated using a densitometry-assisted, semiquantitative RT-PCR in clinical tumor specimens. Specific FL gene transcripts were amplified from 12 of 12 surgical samples. In these cases, FL gene expression of significantly lower intensity was also detected in healthy mucosa sampled in the vicinity (2 cm) or at a distance (10 cm) from neoplastic outgrowth. Immunohistochemical studies identified FL-positive cancer cells in 5 of 5 cases tested. No positivity was detected in healthy mucosa epithelia at a distance from the tumor or in stromal cells. FL content in preoperative sera from colorectal cancer patients (n = 13) did not exceed the levels detected in healthy donors (</= 100 pg/ml).

Colorectal Neoplasms↗

PubMed2000

Mechanisms of ischemic preconditioning in skeletal muscle.

BACKGROUND: Ischemic preconditioning (IP) (one or more cycles each consisting of a short period of ischemia and a short period of reperfusion, before the sustained ischemia) reduces ischemia-related organ damage in heart and skeletal muscle but the underlying mechanisms are not clear. This study was intended to assess the possible involvement of K(ATP) channels and of adenosine receptors in IP of skeletal muscle in a rat model of skeletal muscle ischemia. MATERIALS AND METHODS: Groups of 8-15 rats were given the following in vivo treatments: ischemia-reperfusion (I-R: 2.5 h tourniquet-induced ischemia of the right hindlimb, then 2 h reperfusion); IP (three cycles of 5 min ischemia, then 5 min reperfusion) before I-R; cromakalim and I-R; glibenclamide, cromakalim, and I-R; glibenclamide, IP, and I-R; [R]-N(6)-[1-methyl-2-phenylethyl]adenosine (R-PIA) and I-R; adenosine and I-R; and glibenclamide, IP, and I-R. Parameters of muscle function (postischemic maximal force, performance, contraction index, and force after 1 min of stimulation) were then assessed in vitro in the extensor digitorum longus muscle. RESULTS: Pretreatment with either IP or the K(ATP) channel opener cromakalim significantly improved postischemic muscle function. The protective effect of cromakalim was not seen when the K(ATP) channel blocker glibenclamide was added. Glibenclamide, however, did not block IP-induced protection. Pretreatment with the adenosine A(1) receptor agonist 8-(p-sulfophenyl)-theophyllin (8-SPT) or with adenosine did not improve postischemic muscle function. The adenosine receptor agonist did not block IP-induced protection against ischemic damage. CONCLUSIONS: The results show significant improvements in postischemic skeletal muscle function after IP or cromakalim pretreatment but they do not support a role for K(ATP) channels or for adenosine receptors in IP of skeletal muscle.

Animals↗

PubMed2000

Functional outcome of transplanted knee joints in dogs.

Total knee joint transplantation has been performed in animal models and humans. This study investigates the impact of this operation on knee joint function in a dog model. Therefore, replantation was compared to transplantation during a 6-month follow-up period in four dogs in each group. The peak vertical ground reaction force normalized in all legs undergoing replantation and in two of four after transplantation. A third transplant recipient reduced loading from the 4th month due to a local complication, and the fourth succumbed to sepsis 3 months postoperatively. A weight-bearing index (WBI), defined as loading of the grafted divided by loading of both hind-limbs decreased from 0.48 +/- 0.08 preoperatively to 0.13 +/- 0.10 by 1 month after replantation and from 0.53 +/- 0.07 to 0 after transplantation. After 6 months, weight-bearing of all replant recipients was restored, but reduced in two transplant recipients with graft function. Full recovery after replantation, but impaired function after transplantation, was also reflected in the histological results: normal histological pictures of blood vessels, cartilage, bone and soft tissues were found in all replant recipients, but infiltrative vasculopathy indicating chronic rejection was found in the transplanted joints. The results of this animal study confirm that the procedure can lead to satisfactory functional results but also emphasize the need for perfect control of immunosuppression.

Animals↗

PubMed2000

NY-ESO-1 tumour associated antigen is a cytoplasmic protein detectable by specific monoclonal antibodies in cell lines and clinical specimens.

NY-ESO-1 gene encodes a novel member of the cancer/testis (CT) family of human tumour-associated antigens (TAA). Specific monoclonal antibodies (mAb) have identified the corresponding gene product in lysates of tumour cell lines as a 22 kDa protein but no data are available concerning its intracellular location or distribution within neoplastic tissues. We have generated NY-ESO-1 specific mAbs recognizing the target molecule in cytospin preparations and in sections from clinical tumour specimens. These reagents identify NY-ESO-1 TAA in melanoma cell lines expressing the specific gene as a cytoplasmic protein, sharing the intracellular location of most MAGE TAA. In a series of 12 melanoma specimens, specific staining, limited to neoplastic cells, was detectable in the five cases where NY-ESO-1 gene expression was observed. In two of them over 90% of tumour cells showed evidence of positive staining. Lower percentages of positive neoplastic cells ranging between single cells and 50% were observed in the remaining tumours. These data suggest that active specific immunotherapies targeting NY-ESO-1, alone or in combination with other TAA could be of high clinical relevance in sizeable subgroups of melanoma patients.

Antibodies, Monoclonal↗

PubMed2000

Function of fast- and slow-twitch rat skeletal muscle following ischemia and reperfusion at different intramuscular temperatures.

Fast- (peroneal) and slow-twitch (soleus) skeletal muscles of anesthetized Wistar rats were subjected to 3 h of tourniquet ischemia. The intramuscular temperature of the leg was adjusted to 22, 30 or 35 degrees C (n = 12 per group) during ischemia. After 2 h of reperfusion, the muscles were electrically stimulated in vitro and muscular function was analyzed for maximal force, performance, contractility and fatigue. Contralateral nonischemic muscles served as controls. Three hours of ischemia at 30 degrees C did not reduce the function of the peroneal muscles compared to nonischemic controls. The same ischemic stress significantly reduced the function of the soleus muscles compared to nonischemic controls. The postischemic function of the soleus muscles declined with increasing temperature. The postischemic function of the 35 degrees C group of peroneal muscles was significantly reduced compared to the 22 and the 30 degrees C groups, which did not differ. These results provide evidence that fast-twitch muscles are more resistant to ischemia than slow-twitch muscles. They furthermore show a fiber type-specific dependency of postischemic muscle function on intramuscular temperature during ischemia. Hypothermia-sensitive fast-twitch fibers predominate in the skeletal muscles of the extremities. Mild hypothermia could, therefore, reduce tourniquet ischemia-induced injury after surgery of the extremities.

Animals↗

PubMed2000

Preconditioning with short cycles improves ischemic tolerance in rat fast- and slow-twitch skeletal muscle.

AIM: The aim of this study was to investigate whether the efficacy of ischemic preconditioning (IP) in rat skeletal muscle depends on the duration of the preconditioning cycles. METHODS: Rats were divided into four groups (n = 10 each). The right hindlimb of rats in group A were subjected to 2.5 h of tourniquet ischemia followed by 2 h of reperfusion (I-R). Thereafter, muscular function was analyzed in vitro and high-energy phosphates (HEP) were determined by HPLC. Before I-R, right hindlimbs of rats in groups B-D subjected to IP with three cycles each consisting of 2.5, 5 or 10 min of ischemia followed by reperfusion for the same duration. RESULTS: Postischemic function of the extensor muscle was significantly improved with all three preconditioning protocols. Postischemic function of the soleus muscle was only improved by IP with three cycles of 5 min of ischemia and 5 min of reperfusion. Postischemic HEP tissue levels were not influenced by IP. CONCLUSION: This study shows for the first time that IP increases ischemic tolerance not only of fast-twitch but also of slow-twitch skeletal muscle. The efficacy of IP seems to be less dependent on the duration of the single preconditioning cycle than on the number of cycles performed. Three cycles each of 2.5, 5 or 10 min ischemia and reperfusion significantly improved postischemic skeletal muscle function. Tissue levels of HEPs, however, were not influenced by IP indicating that preservation of HEPs does not play a major role in the effects of IP on rodent skeletal muscle.

Adaptation, Physiological↗

PubMed2000

Knowledge and acceptance of telemedicine in surgery: a survey.

A questionnaire was sent to the chief surgeons at 141 Swiss hospitals to evaluate their knowledge and acceptance of telemedicine in surgery. The response rate was 69%. Ninety-three per cent of all surgical departments used computer technology, 85% regularly used the Web and 88% had an internal hospital network. ISDN lines were used in 58% of the participants' hospitals. While 35% of respondents had participated at least once in networking, only 8% regularly used telemedicine. The opinion was that access to therapeutic advice (87%) was a better use of telemedicine than was obtaining a primary diagnosis (24%), although the majority accepted the principle of making (91%) and receiving (94%) a remote diagnosis. The survey suggested that surgeons are interested in telemedicine and open to its development, although their experience and knowledge are limited. Therefore, telemedicine in surgery may be advanced by creating surgical networks for teleconsultation and tele-education.

Health Knowledge, Attitudes, Practice↗

PubMed1999

[Economics in intensive care medicine: rationalization or rationing?].

Four thesis related to economics of intensive care medicine are derived from an analysis of the intensive care unit of the university hospital of Basel, Switzerland, and the respective literature: (1) Intensive care medicine is costly but rationing can be avoided by rationalization. (2) Exemption or withdrawal of intensive care cannot be justified in the absence of accurate predictors of costs and outcomes of individual patients. (3) Intensive care physicians must not act as judges but on behalf of patients incapable of decision making. They must represent patients' interests vis-à-vis authorities and reimbursing institutions. (4) Analyses of cost-efficiency are instrumental for process improvement of intensive care, for negotiations on reimbursement and for the regulatory decisions of the authorities. Tools for economic analyses of intensive care medicine are therefore worthy of further development.

Costs and Cost Analysis↗

PubMed1998

Enhanced generation of cytotoxic T lymphocytes using recombinant vaccinia virus expressing human tumor-associated antigens and B7 costimulatory molecules.

In this work, we addressed the possibility to enhance the "in vitro" generation of CTLs recognizing tumor-associated antigens (TAAs) by using an inactivated recombinant vaccinia virus encoding B7.1 and B7.2 costimulatory molecules (rVV-B7.1/2). Antigen presenting cells (APCs) infected by rVV-B7.1/2 and pulsed with MART-1/Melan-A27-35 HLA-A2.1-restricted peptide induced significantly higher specific cytotoxic activity than peptide-loaded APCs infected by wild-type VV, both in VV-sensitized and naive donors. When APCs were infected with a rVV encoding both MART-1/Melan-A27-35 and B7-1/2 (rVV-B7.1/2-M), a significantly more effective CTL generation was observed as compared with cultures stimulated by APCs infected with a rVV encoding the TAA epitope only (rVV-M). These enhancing effects were detectable irrespective of a previous VV-specific sensitization. Most importantly, fibroblasts, devoid of antigen-presenting capacity upon peptide pulsing or infection with rVV-M, could be turned into effective APCs after infection by rVV encoding TAA epitopes and costimulatory molecules. In these experiments, by using separate recombinant viral constructs, we observed a predominant role of B7-1 as compared with B7-2 in the induction of TAA-specific CTLs. Taken together, our data indicate that replication-incompetent rVV encoding TAA epitopes and costimulatory molecules are able to induce highly effective generation of tumor-specific CTLs. Therefore, these vectors could represent valuable clinical tools for immunotherapy of melanoma patients.

Antigen-Presenting Cells↗

PubMed1998

GM-CSF gene expression and protein production in human colorectal cancer cell lines and clinical tumor specimens.

Granulocyte-macrophage colony stimulating factor (GM-CSF) gene expression and protein production were investigated in colorectal cancer cell lines and surgical specimens. In 6 of 6 established tumor lines, expression of the GM-CSF gene was observed by reverse transcription polymerase chain reaction (RT-PCR). Furthermore, for 2 of the lines, the cytokine was detectable in > or = 100 pg/ml amounts in culture supernatants by enzyme-linked immunosorbent assay tests. Addition of recombinant GM-CSF at doses ranging between 30 pg and 30 ng/ml did not appear to affect the proliferation of colorectal cancer cell lines as measured by 3H-thymidine incorporation. GM-CSF gene expression was then examined in surgical specimens by a densitometry-assisted, semiquantitative RT-PCR technique. In the 10 samples analyzed, significantly higher expression was detectable in tumors, as compared with autologous healthy mucosa sampled in the vicinity (2 cm) or at distance (10 cm) from the neoplastic focus. Immunohistochemistry studies performed on 13 specimens led to the identification of intracytoplasmic GM-CSF in tumor cells in 9 samples. In 6 of these, positivity of stromal fibroblasts and lymphocytes adjacent to the tumor was also observed. In contrast, intracellular GM-CSF was only detectable in 2 cases in untransformed epithelial cells, close to the neoplasm, but never in healthy mucosa at distance from the tumor. Infiltration by dendritic cells (DC) was also investigated. In 5 of 8 colorectal cancers tested, DC aggregates accounted for more than 10% of stromal cells. Lower numbers were detectable in healthy mucosa. However, DC infiltration could not be correlated with the presence of GM-CSF-positive neoplastic cells in the tumor specimens. Remarkably, cultured DC were unable to exert significant cytotoxic activity against colorectal cancer cells in vitro.

Aged↗

PubMed1998

C-type lectin-like receptors in peptide-specific HLA class I-restricted cytotoxic T lymphocytes: differential expression and modulation of effector functions in clones sharing identical TCR structure and epitope specificity.

C-type lectin-like inhibitory receptors are heterodimers consisting of CD94 and NKG2-A-B molecules expressed on NK cells and on a subset of activated T lymphocytes. Their inhibitory effects on NK cytotoxicity and on the NK-like activity of T cell clones have been demonstrated, but no data are currently available on antigen-specific class I-restricted cytotoxic T lymphocytes (CTL). We have generated a panel of HLA-A2.1-restricted CTL clones directed against a nonapeptide derived from a melanoma-associated antigen, dopachrome tautomerase (TRP-2). All clones were CD8+ and TCR alphabeta+. About half of them expressed a CD94bright phenotype, whereas the remaining were CD94dim. Only the CD94bright CTL expressed the NKG2-A-B gene, consistent with the expression of a C-type, lectin-like, inhibitory CD94/NKG2-A-B heterodimer. Both CD94bright and CD94dim clones appeared to require similar amounts of synthetic epitope sensitizing target cells. Addition of anti-CD94 mAb resulted in a significant increase of specific killing by CD94bright, but not by CD94dim clones in the presence of suboptimal concentrations of peptide, whereas, when optimal amounts were used, the mAb did not induce a significant modulation of the cytotoxicity. Antigen-induced inward [Ca2+]i fluxes were unaffected, but an enhancement of TCR down-modulation could be observed in the presence of anti-CD94 mAb at high concentration of antigenic peptide. The analysis of the TCR-Vbeta repertoire of the CTL clones by RT-PCR and immunofluorescence revealed that all clones regardless of CD94 phenotype shared Vbeta22 expression. Most importantly, sequence analysis showed that they all expressed identical Vbeta22 TCR rearranged with Jbeta2.1 and Cbeta2. Taken together, these data indicate that different expression of functionally active lectin-like inhibitory receptors can be detected in CTL clones sharing identical TCR sequence and peptide specificity.

Amino Acid Sequence↗

PubMed1998

[Success factors in hospital management].

The hospital environment of most Western countries is currently undergoing dramatic changes. Competition among hospitals is increasing, and economic issues have become decisive factors for the allocation of medical care. Hospitals therefore require management tools to respond to these changes adequately. The balanced scorecard is a method of enabling development and implementation of a business strategy that equally respects the financial requirements, the needs of the customers, process development, and organizational learning. This method was used to derive generally valid success factors for hospital management based on an analysis of an academic hospital in Switzerland. Strategic management, the focus of medical services, customer orientation, and integration of professional groups across the hospital value chain were identified as success factors for hospital management.

Cost-Benefit Analysis↗

PubMed1998

Clinical results using the trochanter stabilizing plate (TSP): the modular extension of the dynamic hip screw (DHS) for internal fixation of selected unstable intertrochanteric fractures.

OBJECTIVE: To evaluate whether the implantation of the modular trochanter stabilizing plate (TSP) in addition to the dynamic hip screw (DHS) prevents excessive telescoping and limb shortening in four-part and selected three-part trochanteric fractures. DESIGN: Prospective clinical study. SETTING: The study was conducted at the trauma unit of the Surgical Department of the University of Basel, Switzerland. PATIENTS: Forty-six consecutive patients with unstable intertrochanteric fractures were treated with an additional TSP super-imposed on the regular DHS at our institution between July 1991 and July 1993. Five patients died before the first follow-up, one patient was lost to follow-up, and another patient refused follow-up. Thus, thirty-nine patients were followed for at least twelve months (mean 14 months, range 12 to 20 months). INTERVENTION: The fractures treated were classified according to the OTA classification, which is based on the AO classification. Seventeen were 31-A2.2, seven were 31-A2.3, and fourteen were 31-A3.3 fractures. RESULTS: Lateralization of the greater trochanter was successfully prevented in all fractures. Limited fracture impaction was found in 90 percent (n = 35) of the patients with telescoping of 9.5 millimeters (range 0 to 30 millimeters), resulting in mean limb shortening of 5.37 millimeters (range 0 to 14.9 millimeters). Four patients suffered limb shortening exceeding fifteen millimeters (range 15.6 to 21.3 millimeters). Functional results were excellent and good in 87 percent of patients and fair in 13 percent according to the Salvati-Wilson score. All fractures had healed six months after the operation. Three complications required a secondary procedure: one from not inserting a second screw parallel to the gliding hip screw to prevent rotation of the head-neck fragment ("antirotation screw"), one because of deep infection, and one because of a refracture after premature implant removal. CONCLUSION: In unstable pertrochanteric fractures with small or missing lateral cortical buttress, the addition of a TSP to the DHS effectively supports the unstable greater trochanter fragment and can prevent rotation of the head-neck fragment. Excessive fracture impaction and consecutive limb shortening was prevented by this additional implant in 90 percent of these patients.

Adult↗

PubMed1998

[B7 costimulation molecules improve induction of tumor specific cytotoxic T-cells against MART-1(27-35)].

The expression of B7-1/2 molecules in addition to TAA in APC significantly improves the generation of specific CTL in vitro. Moreover, human fibroblasts, usually devoid of APC capacity, can be engineered into effective APC upon infection with recVV encoding costimulatory molecules together with specific epitopes. The generation of artificial APC by infection of non professional APC with appropriately engineered recVV is a new concept that may be useful in the implementation of immunotherapy strategies.

Antigens, CD↗

PubMed1998

[Recombinant vaccinia viruses as efficient vectors of biologically active, human B7 costimulation molecules].

A specific antigenic ligand and a costimulatory signal are required for optimal T cell activation. We constructed and tested recombinant Vaccinia viruses (recVV) expressing hB7-1 or hB7-2 as a gene expression vector system for delivery of costimulatory function in vitro. Upon infection with replication incompetent and non-cytopathic recVV B7, all human tumour cell lines tested expressed the recombinant molecules. Cell lines expressing recombinant B7 molecules provided effective costimulation for proliferation of resting CD4+ T helper cells in the presence of suboptimal PMA concentrations. The costimulatory effect could be blocked with soluble CTLA-4 proteins. RecVV B7-1 infected EBV transformed B-lymphocytes overexpressed the costimulatory molecules resulting in enhanced costimulation. The capacity of these cells to stimulate autologous CD4+ memory cells of VV immunocompetent donors was not impared by the recVV infection indicating an intact capacity for processing and presenting antigenic proteins in the context with MHC Class II molecules remained. RecVV encoding human B7 molecules therefore appear to be promising experimental and clinical tools to enhance immune responses.

B-Lymphocytes↗