Biomedical subjects

T H Tötterman

Publications and source records attributed to T H Tötterman.

At least 19 recordsLinked to original sources

PubMed2006

An oncolytic conditionally replicating adenovirus for hormone-dependent and hormone-independent prostate cancer.

The use of conditionally replicating adenoviruses offers an attractive complementary treatment strategy for localized prostate cancer. We have produced a replicating adenovirus, Ad[I/PPT-E1A], where E1A gene expression is controlled by a recombinant regulatory sequence designated PPT. The PPT sequence comprises a PSA enhancer, a PSMA enhancer and a T-cell receptor gamma-chain alternate reading frame protein promoter, and it is shielded from transcriptional interference from adenoviral backbone sequences by an H19 insulator. Ad[I/PPT-E1A] yields prostate-specific E1A protein expression, viral replication and cytolysis in vitro. Furthermore, Ad[I/PPT-E1A] considerably regresses the growth of subcutaneous LNCaP prostate cancer tumors in nude mice. Importantly, the viral replication and cytolytic effect of Ad[I/PPT-E1A] are independent of the testosterone levels in the prostate cancer cells. This may be beneficial in a clinical setting since many prostate cancer patients are treated with androgen withdrawal. In conclusion, Ad[I/PPT-E1A] may prove to be useful in the treatment of localized prostate cancer.

Adenoviridae↗

PubMed2005

Optimization of the MB49 mouse bladder cancer model for adenoviral gene therapy.

Bladder cancer is regarded as a promising candidate for innovative therapies in the field of immune and gene therapy. In this paper, we present the subcutaneous, metastatic and a novel orthotopic model of murine MB49 bladder cancer in C57BL/6 mice. We further show the potential of using adenoviral vectors together with different transduction enhancers to augment in vivo gene delivery. Finally, we present candidate genes for tumour detection, therapy or targeting. The MB49 tumour grew rapidly in mice. The subcutaneous model allowed for tumour detection within a week and the possibility to monitor growth rate on a day-by-day basis. Injection of MB49 cells intravenously into the tail vein gave rise to lung metastases within 16 days, while instillation of tumour cells into pretreated bladders led to a survival time of 20-40 days. Adenoviral vectors can be used as a vehicle for gene transfer to the bladder. By far, the most potent transduction enhancer was Clorpactin, also known as oxychlorosene. Last, we show that MB49 cells express tumour-associated antigens like bladder cancer-4, prostate stem cell antigen and six-transmembrane epithelial antigen of the prostate. Given the possibility for efficient genetic modification of the bladder and the presence of known tumour antigens, the MB49 models can be used in innovative ways to explore immunogene therapy.

Adenoviridae↗

PubMed2002

Human urinary bladder carcinomas express adenovirus attachment and internalization receptors.

The use of adenoviral vectors as potent gene delivery systems requires expression of the Coxsackievirus/adenovirus receptor (CVADR) on the target cell surface. This receptor is important for virus attachment to the cell surface. For effective internalization of the vector into the target cell the integrins alpha(v)beta(3) and/or alpha(v)beta(5) are needed. Since there have been reports of loss of CVADR in bladder cancer cell lines, we wanted to investigate the expression of this receptor in bladder carcinoma biopsies. Surgical biopsies, as well as five human bladder cancer cell lines, were analyzed for expression of CVADR, the integrins alpha(v)beta(3) and alpha(v)beta(5) and MHC class I. Further, we studied the ability to transduce these cell lines using adenoviral vectors. Immunohistochemistry revealed that all biopsies (27/27) were positive for CVADR. Some variation in expression was evident, and superficially growing tumors stained more strongly than invasive ones. Most human tumors expressed the integrin alpha(v)beta(5) (14/24), whereas integrin alpha(v)beta(3) was less frequently seen (3/20). The established cell lines were efficiently transduced with adenoviral vectors, and transduction could be reduced with anti-CVADR antibodies. The abundance of appropriate viral receptors on tumor biopsy cells is a further argument for using adenoviral vectors in gene therapy of bladder cancer.

Adenoviridae↗

PubMed2001

Multiple myeloma cells are killed by syndecan-1-directed superantigen-activated T cells.

Multiple myeloma (MM) is an incurable plasma cell/plasmablast malignancy with a great need for innovative treatment strategies. Since experimental immunotherapy with targeted superantigens (SAg) proved to be effective in other haematopoietic tumours, we investigated whether this would also hold true for MM. We used the bacterial SAg Staphylococcus enterotoxin A (SEA), a potent activator of T cell cytotoxicity by means of its binding to particular T cell receptor Vbeta sequences on effector cells and MHC class II molecules on target cells. To eliminate potentially unspecific binding via MHC class II, SEA was point mutated (SEAm). In a second step SEAm was genetically fused to protein A (PA), resulting in a fusion protein (PA-SEAm). This fusion protein was used together with four different plasma-cell-specific/associated mAbs to direct T cells towards 10 MM target cell lines. Three of these mAbs were directed against syndecan-1/CD138, known to be highly expressed on MM and plasma cells, but absent on other haematopoietic cells. All MM cell lines proved to be sensitive to SAg-activated T cell killing (15-50% lysis), as measured in a 51Cr-release assay. This effect was clearly mediated via the plasma-cell-reactive antibodies, as control antibodies only conferred a low background lysis. MM therapy based on targeted SAgs could in theory be hampered by dysfunctional T cells in MM patients. However, we show that T cells from MM patients and healthy controls responded equally well to activation by SAg.

Antibodies, Monoclonal↗

PubMed2001

Circulating soluble vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in immunocompetent and renal transplant patients: correlation with cytomegalovirus disease and renal function.

The plasma levels of the soluble adhesion molecules, soluble vascular cell adhesion molecule-1 (sVCAM-1) and intercellular adhesion molecule-1 (sICAM-1), were measured before and after transplantation in 26 renal transplant recipients, and in 173 longitudinally collected samples in 17 of the patients. The patients were carefully monitored for the presence of cytomegalovirus (CMV) infection and rejection. Forty healthy blood donors and 12 otherwise healthy subjects with symptomatic primary CMV infections served as controls. During CMV disease, plasma levels of sVCAM-1 and sICAM-1 were elevated in both renal transplant patients and otherwise healthy subjects with CMV disease. The sVCAM-1 levels were strongly elevated before transplantation in renal transplant recipients and correlated with creatinine levels. Increased sVCAM-1 levels were also registered during rejection episodes. CMV disease, per se, is associated with markedly increased levels of sVCAM-1 and sICAM-1. There is also a correlation of sVCAM-1 levels with serum creatinine levels. Thus, the presence of CMV infection and renal function are factors that must be considered in further studies of soluble adhesion molecules.

Adolescent↗

PubMed2001

Potent antitumor effects of CD154 transduced tumor cells in experimental bladder cancer.

PURPOSE: Current intravesical immunotherapy for bladder cancer with bacillus Calmette-Guerin instillations is standard treatment for patients with high risk superficial tumors but relapses are common. We evaluated the tumor vaccine concept in murine bladder cancer by comparing tumor cell transduction with genes coding for the immunostimulatory molecules CD154, interleukin (IL)-12 and CD80 to design a novel vaccination strategy. MATERIALS AND METHODS: Adenoviral vectors were used to transduce murine bladder cancer MB-49 cells with genes coding for CD154, IL-12 and CD80. Parental or transduced MB-49 cells were injected subcutaneously into syngeneic mice. The effects of transgene expression on tumorigenicity and the generation of protective immunological memory against challenge with parental tumor were studied. RESULTS: All 76 animals injected with parental MB-49 cells had tumors within 8 to 12 days. Tumor cell expression of CD154 combined with IL-12 completely inhibited tumor outgrowth with all 21 mice tumor-free and CD154 transduction alone was almost as effective with 33 of 35 tumor-free. IL-12 production by tumor cells delayed tumor outgrowth and 4 of 10 mice remained tumor-free. Over expression of CD80 had no effect on tumorigenicity. CD154 expressing tumors were rapidly infiltrated with large numbers of CD4+ and CD8+ T cells. Mice vaccinated 4 times with adenoviral CD154 transduced MB-49 cells were completely protected against challenge with parental tumor. Co-injection of CD154 modified cells with parental MB-49 cells retarded tumor growth. CONCLUSIONS: Our experimental results suggest that the potent antitumor effects of CD154 gene transduction should be considered for immunostimulatory gene therapy for bladder cancer.

Animals↗

PubMed2000

Characterization of CMVpp65-specific CD8+ T lymphocytes using MHC tetramers in kidney transplant patients and healthy participants.

BACKGROUND: Cytomegalovirus (CMV) is a ubiquitous herpesvirus that infects 50-90% of individuals in different populations. After primary infection, the virus persists latently in myeloid cells under the control of specific T-cells. Reactivation of CMV infection may cause lethal organ dysfunction and is frequently seen in immunosuppressed individuals. CD8+ cytotoxic T-cells (CTL) have a primary role in suppressing CMV reactivation, and the dominating CTL response is directed against pp65. METHODS: MHC tetramers, that is, complexes between HLA class I (or class II) molecules and antigenic peptides conjugated to fluorochromes allow the direct visualization of antigen-specific receptor-carrying T-cells using flow cytometry. We constructed a novel MHC tetramer for identification of CMVpp65-specific CD8+ T-cells using HLA-A2 molecules folded with the immunodominant NLVPMVATV peptide. RESULTS: The A2/pp65 tetramer specifically stained CMV-directed T-cell lines, and sorted cells showed CMV-specific cytotoxicity. High proportions (0.1-9%) of the CD8+ T-cells were A2/pp65 tetramer+ in healthy HLA-A2+ CMV carriers and in immunosuppressed kidney transplant patients with latent infection. Patients with reactivated CMV infection exhibited up to 15% A2/pp65 tetramer+ cells, which seemed to correlate with CMV load over time. A2/pp65 tetramer+ cells expressed T-cell activation markers. CONCLUSIONS: The construction of a novel A2/pp65 MHC tetramer enabled the design of a rapid and precise flow cytometric method allowing quantitative and qualitative analysis of CMV-specific T-cells. The number of A2/pp65 tetramer binding CTLs in blood may prove to be clinically relevant in assessing the immune response to CMV.

Adult↗

PubMed1999

Staphylococcus aureus Cowan strain 1 activation of B-chronic lymphocytic leukaemia cells augments the response to CD40 stimulation.

The signals involved in regulating the proliferation, differentiation and survival of B-chronic lymphocytic leukemia (B-CLL) cells are fully understood. B-CLL cells have been found to respond poorly to various activation signals and only after successful Epstein-Barr virus (EBV) transformation has it been possible to maintain such cells in long-term cultures. In this work we describe a new method to activate and induce proliferation in B-CLL cells and to maintain such cells in long-term culture for longer than 1 month. We used a combination of protocols in an attempt to mimic some of the signals of a thymus-dependent immune response. The B-CLL cells were first activated with Staphylococcus aureus Cowan strain 1 (SAC) particles plus thioredoxin (Trx), followed by stimulation with interleukin (IL)-2 + Trx. This treatment primed the cells for further stimulation with anti-CD40 monoclonal antibody (MoAb) presented on irradiated CD32L cells (the CD40-system) or soluble CD40 Ligand, and a combination of Trx and cytokines (IL-4 + IL-10), which allowed the cells to be maintained for up to 1 month with preserved viability and a variable rate of proliferation. However, induced proliferation of the B-CLL cells was limited to approximately 1 month, suggesting that additional signals are required to facilitate further proliferation.

Burkitt Lymphoma↗

PubMed1999

Serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) are elevated in advanced stages of non-Hodgkin's lymphomas.

The serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured in 116 patients with non-Hodgkin's lymphomas (NHL) tested previously for soluble intercellular adhesion molecule-1 (sICAM-1). In contrast to Hodgkin's disease and chronic lymphocytic leukaemia, the sVCAM-1 levels in NHL patients were not significantly different from the levels of healthy controls (n = 31). However, sVCAM-1 was elevated in advanced stage disease, i.e. stages III + IV. Elevated serum levels of sVCAM-1 were associated with significantly poorer disease-free (p = 0.024) and overall (p = 0.02) survival. sVCAM-1 correlated poorly with other known prognostic variables (LDH, sTK and beta 2m) and with sICAM-1. None of the tested markers added prognostic information for disease-free survival independently of Ann Arbor stage and B-symptoms. The expression of VCAM-1 and ICAM-1 in tumour biopsies from 15 patients representing 7 different histologies were examined and compared with the serum levels of the soluble adhesion molecules. No correlation was found between the adhesion molecule expression by vascular endothelium and the corresponding serum levels.

Adult↗

PubMed1998

Soluble vascular cell adhesion molecule-1 (sVCAM-1) is an independent prognostic marker in Hodgkin's disease.

Serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1. sCD106) were significantly elevated in patients with Hodgkin's disease (HD) (n = 101) compared to controls (n= 31) (P<0.0001). sVCAM-1 correlated with histology, stage, B-symptoms, and prognostic markers (sICAM-1, sCD30, sIL-2R, LDH). sVCAM-1, sICAM-1 and sCD30 added independent prognostic information for both disease-free and overall survival. 14 biopsies from 13 patients with HD were immunostained for VCAM-1 and ICAM-1. The vascular endothelium stained positive for VCAM-1 in 10/12 evaluable biopsies and for ICAM-1 in all evaluable biopsies. A stromal expression of both adhesion molecules precluded a precise evaluation of HRS-cells. This led us to investigate VCAM-1 (and ICAM-1) expression in six Hodgkin cell lines (HDLM-2, L428, L540, L591, DEV, KM-H2). Two cell lines stained positive for VCAM-1 (HDLM-2, L591). All cell lines stained positive for ICAM-1. sVCAM-1 is a new prognostic marker in HD; its predictive power equals or surpasses that of sCD30 and sICAM-1. Furthermore, two Hodgkin cell lines stained positive for VCAM-1. This indicates that VCAM-1 may be expressed by some HD tumour cells in vivo.

Adolescent↗

PubMed1998

Elevated serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) closely reflect tumour burden in chronic B-lymphocytic leukaemia.

The present study is the first to report elevated serum levels of soluble (s)VCAM-1 in B-cell chronic lymphocytic leukaemia (B-CLL). A large cohort of 106 untreated patients was studied. sVCAM-1 was compared to known prognostic serum markers (soluble (s)ICAM-1; lactate dehydrogenase, LDH; sCD23; thymidine kinase, TK; beta2microglobulin, beta2m). The serum levels of sVCAM-1 reflected tumour burden as expressed by Binet/Rai stages more closely than any other marker. sVCAM-1 also reflected the kinetics of the disease as revealed by lymphocyte doubling time. sVCAM-1 was the only one of the studied markers which showed elevated levels in smouldering disease compared to controls. sVCAM-1, sICAM-1 and sCD23 (but not LDH, TK, beta2m) separated smouldering from non-smouldering B-CLL. Only sICAM-1, sCD23 and TK added independent prognostic information for survival to that of stage and lymphocyte doubling time. The expression of both adhesion molecules was examined in lymph node and splenic specimens. VCAM-1 and ICAM-1 were overexpressed by vascular endothelium and stroma, but the intensity of expression correlated poorly with serum levels of the soluble molecules. In conclusion, serum levels of sVCAM-1 correlated with tumour burden and other prognostic markers in B-CLL. VCAM-1 was overexpressed in tumour tissue as was ICAM-1. sVCAM-1 could prove a valuable marker in younger early-stage patients eligible for therapeutic trials.

Adult↗

PubMed1998

Targeted superantigens for immunotherapy of haematopoietic tumours.

With the exception of childhood common acute lymphoblastic leukaemia (cALL), treatment of other hematopoietic B cell lineage tumours such as non-Hodgkin's lymphoma (B-NHL), adult ALL and multiple myeloma (MM) is unsatisfactory. Similarly, the therapeutic outcome of acute and chronic myeloid leukaemia (AML, CML) is frequently dismal. At the same time, leukaemia/lymphoma cells represent ideal targets for immunotherapy. The present review summarizes our preclinical experience with a novel type of cytotoxic T cell based immunotherapy for B-lineage and myeloid tumours. Staphylococcal enterotoxin-derived superantigens (SAgs) are among the most potent T cell activators known, linking the T cell receptor to HLA-DR on natural target cells. SAgs were genetically engineered to reduce DR binding and were then fused to Fab parts of tumour-directed monoclonal antibodies (mAbs). Using these "targeted" SAgs, highly efficient lysis of B-lineage (B-NHL, B-CLL, ALL, MM) and myeloid (AML, CML) tumour cells by T-cells was achieved in vitro and in an animal model. We are entering an interesting era of innovative cancer therapy based on novel man-made biotherapeutic agents.

Adult↗

PubMed1998

Antibody-directed superantigen-mediated T-cell killing of myeloid leukaemic cell line cells.

Bacterial superantigens (SAgs) bound to MHC class II molecules on target cells are efficient activators of cytotoxic T cells expressing certain T cell receptor (TCR) Vbeta regions We described earlier that the specificity of the SAg Staphylococcus enterotoxin A (SEA) can be changed by introducing a D227A point mutation in the major MHC class II binding site and by genetically fusing the SEA mutant (SEAm) to protein A (PA). This SEAm-PA fusion protein can then be used to direct cytotoxic T cells to tumour cells coated with monoclonal antibodies (mAbs). In this communication, we tested the PA-SEAm fusion protein together with mAbs against the myeloid cell surface antigens CD13, CD15 and CD33. A SEA-reactive T cell line was used as effector cells against 10 different myeloid leukaemic cell lines. Optimal lysis of antigen positive leukaemic cells was obtained at a PA-SEAm concentration of 1 ng/ml and effector : target cell ratios of 15 : 1. No correlation between target cell sensitivity and the level of surface antigen expression could be seen. The 6 acute myeloid leukaemia (AML) cell lines tested appeared to be more sensitive than the 4 chronic myeloid leukaemia (CML) cell lines. The sensitivity of the AML cell line HL-60 could be improved further by stimulation with TNFalpha. This was accompanied by increased surface ICAM-1 expression whereas specific target molecule expression (CD13, CD33) was unchanged. This suggests that sensitivity to lysis is related to the leukaemic subtype and ICAM-1 expression but not to the tumour antigen density. Our results show that it is possible to direct cytotoxic T cells to myeloid leukaemia cells by using SAgs linked to mAbs, and encourage the construction and testing of a recombinant direct SAg-mAb fusion protein as a candidate drug for therapy of myeloid leukaemias.

Antibodies, Monoclonal↗

PubMed1998

Serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) are elevated in advanced stages of non-Hodgkin's lymphomas.

The serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1) were measured in 116 patients with non-Hodgkin's lymphomas (NHL) tested previously for soluble intercellular adhesion molecule-1 (sICAM-1). In contrast to Hodgkin's disease and chronic lymphocytic leukaemia, the sVCAM-1 levels in NHL patients were not significantly different from the levels of healthy controls (n=31). However, sVCAM-1 was elevated in advanced stage disease, i.e. stages III+IV. Elevated serum levels of sVCAM-1 were associated with significantly poorer disease-free (p = 0.024) and overall (p = 0.02) survival. sVCAM-1 correlated poorly with other known prognostic variables (LDH, sTK and beta2m) and with sICAM-1. None of the tested markers added prognostic information for disease-free survival independently of Ann Arbor stage and B-symptoms. The expression of VCAM-1 and ICAM-1 in tumour biopsies from 15 patients representing 7 different histologies were examined and compared with the serum levels of the soluble adhesion molecules. No correlation was found between the adhesion molecule expression by vascular endothelium and the corresponding serum levels.

Adult↗

PubMed1997

A superantigen-antibody fusion protein for T-cell immunotherapy of human B-lineage malignancies.

The bacterial superantigen staphylococcal enterotoxin A (SEA) is an efficient activator of cytotoxic T cells when presented on major histocompatibility complex (MHC) class II molecules of target cells. Our previous studies showed that such SEA-directed T cells efficiently lysed chronic B-lymphocytic leukemia (B-CLL) cells. Next, we made a mutated SEA-protein A (SEAm-PA) fusion protein with more than 1,000-fold reduced binding affinity for MHC class II compared with native SEA. The fusion protein was successfully used to direct T cells to B-CLL cells coated with different B lineage-directed monoclonal antibodies (MoAbs). In this communication, we constructed a recombinant anti-CD19-Fab-SEAm fusion protein. The MHC class II binding capacity of the SEA part was drastically reduced by a D227A point mutation, whereas the T-cell activation properties were retained. The Fab part of the fusion protein displayed a binding affinity for CD19+ cells in the nanomolar range. The anti-CD19-Fab-SEAm molecule mediated effective, specific, rapid, and perforin-like T-cell lysis of B-CLL cells at low effector to target cell ratios. Normal CD19+ B cells were sensitive to lysis, whereas CD34+ progenitor cells and monocytes/macrophages were resistant. A panel of CD19+ B-cell lines representing different B-cell developmental stages were efficiently lysed, and the sensitivity correlated with surface ICAM-1 expression. The anti-CD19-Fab-SEAm fusion protein mediated highly effective killing of tumor biopsy cells representing several types of B-cell non-Hodgkin's lymphoma (B-NHL). Humanized severe combined immune deficiency (SCID) mice carrying Daudi lymphoma cells were used as an in vivo therapy model for evaluation of the anti-CD19-Fab-SEAm fusion protein. Greater than 90% reduction in tumor weight was recorded in anti-CD19-Fab-SEAm-treated animals compared with control animals receiving an irrelevant Fab-SEAm fusion protein. The present results indicate that MoAb-targeted superantigens (SAgs) may represent a promising approach for T-cell-based therapy of CD19+ B-cell malignancies.

Animals↗

PubMed1997

Comparative studies of antimitochondrial autoantibodies in sera and bile in primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is an autoimmune liver disease characterized by destruction of intrahepatic bile ducts. Although the pathogenesis of this disease is still unknown, high titers of antimitochondrial autoantibodies (AMA) have long been recognized in patient sera. However, little is known about the presence of AMA in bile. In this study, we investigated bile and sera from patients with PBC and healthy controls for the presence of AMA and mitochondrial autoantigens. AMA were detected in the bile of 17 of 19 patients (89.4%) with PBC; they were specifically directed against the pyruvate dehydrogenase complex (PDC-E2) in 15 of 19 patients (78.9%), to the branched-chain 2-oxo-acid dehydrogenase complex E2 (BCOADC-E2) in 6 of 19 patients (31.6%), and to the 2-oxoglutarate dehydrogenase complex E2 (OGDC-E2) in 1 of 19 patients (5.3%). In a comparative study of sera from the same patients, anti-PDC-E2 antibodies were found in 19 of 19 patients (100%), anti-BCOADC in 9 of 19 patients (47.3%), and anti-OGDC-E2 in 4 of 19 patients (21.1%) patients. AMA in bile were always found together with antibodies of corresponding specificities in the serum from the same patient. Immunoglobulin (Ig)A AMA were found in the bile of 9 of 19 patients (47.7%) with PBC; they were specifically directed against PDC-E2 in 8 of 19 patients (42.1%) and to BCOADC in 2 of 19 patients (10.5%). Epitope mapping of IgA anti-PDC-E2 antibodies indicated that, like serum autoantibodies, the immunodominant epitope is directed against the inner lipoyl domain of PDC-E2. The prevalence and antigen reactivity of IgA AMA in sera correlated completely with IgA AMA in bile. Autoantibodies against nuclear envelope pore proteins (gp210) were found in 1 of 8 (12.5%) sera of patients with PBC, but not in bile. Furthermore, and of particular interest, we detected the autoantigens, PDC-E2, OGDC-E2, and BCOADC-E2, in the bile of 12 of 19 patients (63.2%), 9 of 19 patients (47.4%), and 9 of 19 patients (47.4%), respectively; PDC-E2 was found in only 1 of 17 (5.9%) disease controls. Although the presence of AMA in bile may merely reflect the presence of these antibodies in sera, the simultaneous detection of mitochondrial autoantigens in bile suggests an increase of mitochondrial autoantigens at inflammatory sites. Such autoantigens, coupled with AMA, may augment the local immune response and disease progression.

Autoantibodies↗

PubMed1997

Efficient adenovirus-mediated gene transduction of normal and leukemic hematopoietic cells.

We evaluated the efficiency of adenovirus-mediated gene transfer into normal and malignant human hematopoietic cells. An E-1 and E-3 deleted, replication-defective recombinant Ad.RSV beta gal vector was used and the transduction efficiency was studied at a multiplicity of infection of 13 p.f.u. per cell. Approximately 40-50% of normal monocytes were transduced, whereas purified normal resting T cells and B cells were resistant to infection. We showed that 50-80% of primary chronic myeloid leukemia cells (CML, n = 12) were efficiently transduced in contrast to CML, successful transduction of resting primary chronic B lymphocytic leukemia cells required appropriate preactivation of targeted cells. A novel protocol for the efficient transduction of adenovirus into B-CLL cells was presented. We showed that anti-CD40 mAb or CD40 ligand acts in synergy with rhIL-4 to enable the transduction of approximately 50-75% of B-CLL cells (B-CLL, n = 6). Expression of beta-galactosidase in transduced CML cells and B-CLL cells was detected for at least 15 days after transduction. The present studies underline the utility of adenovirus vectors for the construction of cytokine gene-modified tumor vaccines for the treatment of hematopoietic malignancies such as CML and B-CLL.

Adenoviridae↗

PubMed1997

Ex vivo PKH26-labelling of lymphocytes for studies of cell migration in vivo.

A prerequisite for studies of cell migration is that the cells of interest can be appropriately labelled and subsequently easily traced. The use of radioisotopes or fluorescent substances that bind covalently to the cell surface, e.g. fluorescein isothiocyanate (FITC) or rhodamine isothiocyanate (RITC), have limitations such as rapid loss of the labelling, toxicity and interference with cell surface molecules. In the present work the authors labelled rat spleen lymphocytes with the fluorescent labelling molecule PKH26, which is incorporated into the lipid bilayer of cytoplasmic membranes. The labelled lymphocytes were injected intravenously into syngeneic recipients and 2 or 6 days later the lymphocytes were detected in various organs by using flow cytometry and fluorescence microscopy. As could be expected, the lymphocytes homed to lymphoid tissues, preferably the spleen, and no labelled cells were found in non-lymphoid organs such as the heart and the kidney. Membrane labelling proved to be intense, uniform and stable and PKH26 positive cells were easily detectable in fractions less than 0.2% in peripheral blood and the various tissues after 6 days of in vivo circulation. Thus, the PKH26 dye appears to be suitable for labelling cell populations used in the study of cell migration in vivo, both under normal conditions and when specific immunological processes are taking place, such as graft rejection and tumour growth.

Animals↗