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Biomedical subjects

B Christensson

Publications and source records attributed to B Christensson.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of ex vivo expanded human NK cells on antileukemia activity in SCID-beige mice.

The possibility of using natural killer (NK) cells in treatment of human hematological malignancies has increased in recent years. One factor contributing to this is the introduction of new methods for ex vivo generation of enriched populations of clinical grade NK cells. The objective of the present study was to evaluate the safety and efficacy of human ex vivo expanded clinical grade NK cells against K562 leukemia cells in severe combined immunodeficiency disease (SCID)-beige mice. Irradiated SCID-beige mice were injected intravenously (i.v.) with K562 leukemia cells. Following leukemia cell injection, mice were injected with ex vivo expanded human NK cells. NK cells were followed in vivo and mice monitored for survival from leukemia. Administration of these ex vivo expanded clinical grade NK cells was safe and prevented leukemia development. In conclusion, these results imply possibilities for the use of this NK cell preparation in treatment trials of human hematological malignancies and possibly other forms of cancer.

Animals↗
PubMed2005

Genetically modified autoactivated cells expressing intracellular forms of GM-CSF as a model for regulated administration of cytokines.

The application of cytokines for immunotherapy is frequently hampered by undesirable side effects. To avoid systemic effects, cytokines can be directly expressed in the target cells by using gene transfer. However, the uncontrolled cellular secretion of cytokines could still exert some undesirable bystander effects. Therefore, it is important to develop additional methods for a more restricted administration of cytokines. Recently, using the murine granulocyte-macrophage colony-stimulating factor (mGM-CSF), we have demonstrated that cytokines can be targeted to different subcellular compartments as stable and biologically active proteins. This model could be used as a method of highly restricted administration of cytokines. Here, as model for the proof of principle, we have used a cell line (DA-3) strictly dependent on mGM-CSF for growth and demonstrated that these cells acquired autonomous growth after gene modification with plasmids encoding either extracellular or intracellular forms of mGM-CSF. Cell lines expressing secreted forms of mGM-CSF displayed the highest rates of autonomous growth and released substantial amounts of mGM-CSF. However, cell lines expressing intracellular forms of mGM-CSF also acquired autonomous growth induced by a mechanism of restricted autocrine stimulation and did not release detectable mGM-CSF to the extracellular medium. Cocultivation experiments of DA-3 cell lines expressing intracellular mGM-CSF with unmodified cells showed that there was no activation of the bystander cells. Taken together, these results support the concept that genes encoding intracellular cytokines may be used to provide the desired effect of cytokines on the target cells while avoiding the side effects of their uncontrolled secretion.

Animals↗
PubMed2004

Effect of clonal and serotype-specific properties on the invasive capacity of Streptococcus pneumoniae.

The present study compares the molecular epidemiology of Streptococcus pneumoniae causing invasive disease and carriage, respectively, in one geographic area (Stockholm, Sweden) during a specific point in time (the year 1997). A total of 273 invasive isolates (257 from adults and 16 from children) obtained from the 2 major hospitals in Stockholm, as well as 246 nasopharyngeal isolates recovered from children attending 16 day-care centers in the Stockholm area, were analyzed by serotyping, molecular typing (by pulsed-field gel electrophoresis and multilocus sequence typing), and antibiotic susceptibility testing. Of the 34 different serotypes plus nontypeable strains identified in the present study, 12 were never found among the 246 colonizing isolates, whereas only 3 were never found among the 273 invasive isolates. The isolates formed 2 major classes: 1 class that was found mainly among invasive isolates (type 1, 4, 7F, and 9V isolates) and was clonally highly related and 1 class that caused invasive disease but was also common in carriage (including type 6A, 6B, 14, and 19F isolates) and was genetically more diverse. Clones were found that belonged to the same serotype but had different abilities to cause invasive disease. Also, isolates belonging to the same clone were found, although they had different capsules because of serotype switch, and were found to have the same disease potential. Hence, properties associated with a particular clonal type, in addition to capsular serotype, are likely to be important for the potential of pneumococci to cause invasive disease.

Adult↗
PubMed2003

High level of cannabinoid receptor 1, absence of regulator of G protein signalling 13 and differential expression of Cyclin D1 in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a moderately aggressive B-cell lymphoma that responds poorly to currently used therapeutic protocols. In order to identify tumour characteristics that improve the understanding of biology of MCL, analysis of oligonucleotide microarrays were used to define specific gene expression profiles. Biopsy samples of MCL cases were compared to reactive lymphoid tissue. Among genes differentially expressed in MCL were genes that are involved in the regulation of proliferation, cell signalling, adhesion and homing. Furthermore, some genes with previously unknown function, such as C11orf32, C2orf10, TBC1D9 and ABCA6 were found to be differentially expressed in MCL compared to reactive lymphoid tissue. Of special interest was the high expression of the cannabinoid receptor 1 (CB1) gene in all MCL cases analysed. These results were further confirmed at the cellular and protein level by immunocytochemical staining and immunoblotting of MCL cells. Furthermore, there was a reduced expression of a regulator of G protein signalling, RGS13 in all MCLs, with a complete absence in the majority of cases while present in control lymphoid tissue. These results were further confirmed by PCR. Sequencing of the RGS13 gene revealed changes suggesting polymorphisms, indicating that downregulation of the expression of RGS13 is not related to mutations, but may serve as a new specific marker for MCL. Moreover, comparison between individual cases of MCL, revealed that the CCND1 gene appears to be differently expressed in MCL cases with high vs low proliferative activity.

Adolescent↗
PubMed2003

Expansion of natural killer (NK) and natural killer-like T (NKT)-cell populations derived from patients with B-chronic lymphocytic leukemia (B-CLL): a potential source for cellular immunotherapy.

B-cell chronic lymphocytic leukemia (B-CLL) is the most common leukemia in the Western world. It is currently an incurable disease, making new treatment options such as immunotherapy desirable. Monoclonal antibodies (Mabs) to surface antigens of the tumor cell is one option. Administration of cytotoxic cells such as natural killer (NK) and natural killer-like T (NKT) cells expanded in vitro might be a useful treatment modality alone or in combination with MAbs. A limiting step in the development of successful cellular immunotherapy has been the availability of appropriate cytotoxic cells. Here, we report the feasibility of expanding populations of the human killer cells, CD3-CD56+ NK and CD3+CD56+ NKT cells, from peripheral blood mononuclear cells (PBMCs) of B-CLL patients. The influence of tumor B cells on the in vitro expansion of killer cells was assessed by depleting B cells from PBMCs by microbead separation before culture. The 21-day cultures from both B-cell- and non-B-cell-depleted PBMC showed a marked expansion of NK cells, and also of T cells, among which almost half had the NKT phenotype. Depletion of B cells before culture did not change the expansion rates of NK and NKT cells significantly. In patients with progressive B-CLL, NK cell expansion capacity was improved after fludarabine treatment when compared to samples obtained before treatment. Repeated samples of PBMCs from individual untreated patients with both indolent and progressive disease cultured under identical conditions gave similar NK cell expansion rates. Expanded killer cell populations had cytotoxic function against the NK-sensitive target K562 cell line and expressed high levels of Granzyme B. From our studies, we conclude that NK cells as well as NKT cells from the peripheral blood of B-CLL patients can be expanded, and that these cells have cytotoxic capacity.

Aged↗
PubMed2003

Clonal analysis of Streptococcus pneumoniae nonsusceptible to penicillin at day-care centers with index cases, in a region with low incidence of resistance: emergence of an invasive type 35B clone among carriers.

The nasopharyngeal carriage rate of potential respiratory pathogens was studied in 36 index children with a pneumococci nonsusceptible to penicillin (PNSP), in 595 healthy children, and in 123 personnel at 16 day-care centers (DCCs) with index cases in the Stockholm area, an urban area with a low incidence of antibiotic resistant pneumococci, during the winter of 1997-1998. The spread and clonality of PNSP, Haemophilus influenzae and Moraxella catarrhalis, were studied by analyzing antibiotic susceptibility and serotype, and for PSNP also by using pulsed-field electrophoresis (PFGE) and multilocus sequence typing (MLST). In contrast to the low carriage rate found among the adult contacts (2%), 40% of the children harbored pneumococci, of which 20% were PNSP. Nasopharyngeal colonization decreased with age. The 49 PNSP isolates consisted of 20 clones, of which 10 could be identified in more than one child attending the same or different DCCs. In five DCCs, we observed a spread of PNSP from the index case. A novel PNSP clone of type 35B, found to cause invasive disease in several states in the United States, was found to emerge among several carriers at two DCCs . A high proportion of PNSP isolates were multiresistant to antibiotics (34%), which has implications for treatment regimens, even in a country like Sweden where the proportion of PNSP currently is low (3-4%). One PNSP clone of type 9V found among the carriers, has been shown to cause invasive disease in Sweden as well as in other countries, suggesting that one reason for the occurrence of invasive PNSP clones may be their ability to colonize and spread among healthy carriers. Other internationally spread antibiotic resistant pneumococcal clones found were of types 9V, 19F, and 23F.

Anti-Bacterial Agents↗
PubMed2003

Cryptosporidium parvum and Giardia intestinalis in calf diarrhoea in Sweden.

The objective of this study conducted in 75 herds was to investigate the presence and significance of Criptosporidium parvum and Giardia intestinalis in Swedish dairy calves in comparison with rotavirus, coronavirus and Escherichia coli K99+. The farmers were asked to collect faecal samples from each heifer calf that had diarrhoea between birth and 90 days of age, and also from a healthy calf of the same age. In total, 270 samples were collected and analysed. C. parvum, either alone or together with G. intestinalis and/or rotavirus, was detected in 16 (11%) and 6 (5%) of the samples from diarrhoeic and healthy calves, respectively. Even though a higher proportion of diarrhoeic calves shed C. parvum, the difference between the groups was not statistically significant (p = 0.067), possibly due to the low number of positive samples. G. intestinalis was found in 42 (29%) of the diarrhoea samples and in 29 (23%) of the samples from healthy calves. Rotavirus and coronavirus were demonstrated in 24% and 3% of the diarrhoea samples, respectively, whereas E. coli K99+ was only found in samples from 2 healthy calves. C. parvum and G. intestinalis were found in samples from calves 7 to 84 days of age and during all seasons. The results confirm that C. parvum is present in Swedish dairy herds and might have clinical significance. G. intestinalis was the most common agent found but the importance of this parasite remains unclear. Both parasites have suggested zoonotic potential and thus warrant further attention. In addition, rotavirus is a major pathogen in neonatal enteritis in Sweden, whereas coronavirus and E. coli K99+ seem to be of less importance.

Animals↗
PubMed2002

Evaluation of seven different enzyme-linked immunosorbent assays for serodiagnosis of Staphylococcus aureus bacteremia.

OBJECTIVE: Serologic assays for Staphylococcus aureus antibodies were evaluated regarding their ability to differentiate between uncomplicated and complicated S. aureus bacteremia, between S. aureus and non-S. aureus bacteremia, and between S. aureus and non-S. aureus endocarditis. METHODS: Enzyme-linked immunosorbent assays (ELISAs) were performed to measure Ig G antibodies against seven S. aureus antigens (peptidoglycan, teichoic acid, S. aureus ultrasonicate, whole S. aureus cells, alpha-toxin, lipase and capsular polysaccharide) in 129 patients with S. aureus bacteremia (including 51 with endocarditis), 78 patients with non-S. aureus bacteremia (including 27 with endocarditis) and 100 febrile non-bacteremic controls. RESULTS: Whole-cell ELISA was the most sensitive assay. The specificity of all assays was low. Two different combinations of ELISAs for whole cells, teichoic acid,alpha-toxin, lipase and capsular polysaccharide did distinguish between S. aureus and non-S. aureus endocarditis, but not between uncomplicated and complicated S. aureus bacteremia.

Adult↗
PubMed2002

Cytolytic T cell reactivity to Epstein-Barr virus is lost during in vitro T cell expansion.

In the setting of allogeneic hematopoietic stem cell transplantation, ex vivo culturing of donor T lymphocytes is a necessary step for processes such as gene modification. Often the aim is to enable control of undesired alloreactivity after in vivo administration of the cultured cells. However, it is not fully understood how T cell reactivity against donor and third-party targets is affected by the ex vivo cell culturing process. We have assessed how the activity of anti-Epstein Barr virus (EBV)-specific T lymphocytes from healthy EBV-seropositive donors is affected by in vitro cell culturing. Peripheral blood mononuclear cells (PBMCs) were expanded in X-VIVO 15 culture medium supplemented with 5% human serum. The cells were stimulated by either OKT3 (10 ng/ml) and interleukin (IL)-2 (500 U/ml) or by using anti-CD3/CD28-coated immunomagnetic beads and IL-2 (100 U/ml). Induction of polyclonal EBV-specific cytotoxic T lymphocyte cultures was attempted by stimulation of the in vitro-expanded cells at different time points during the cell expansion process, with pre-established autologous EBV-transformed lymphoblastoid cell lines (LCLs). While EBV-specific cytotoxic T lymphocytes (CTL) were generated from untreated PBMCs of 5 healthy donors, EBV-specific cytotoxicity was significantly decreased or absent in CTL cultures established from in vitro-expanded PBMCs. Our results indicate that the ex vivo cell expansion process itself significantly reduces the activity and/or the number of EBV-specific T cells. Additional stimulation with CD28 antibodies could not prevent this effect. Because T cell depleted bone marrow or stem cell grafts are known to contribute to the development of post transplant lymphoproliferative disorders, this should be taken into consideration if one considers expanding and administering PBMCs in conjunction with a T cell-depleted stem cell grafts.

Cell Culture Techniques↗
PubMed2001

Expression and release of stable and active forms of murine granulocyte-macrophage colony-stimulating factor (mGM-CSF) targeted to different subcellular compartments.

Cytokines have been used for several years as immunomodulators. However, one of the main drawbacks of systemically applied cytokines is their high toxicity. In addition, cytokines work in a paracrine form and frequently after cell-to-cell interaction. Therefore, a very restricted release of cytokines-in time and space-could be desired for most of their therapeutic applications. The murine granulocyte-macrophage colony-stimulating factor (mGM-CSF) is one of the most promising cytokine candidates for cancer immunotherapy and as an adjuvant of DNA vaccines. With the aim of improving the administration and release of cytokines in a very restricted area, we have designed vectors expressing the mGM-CSF cDNA with different localization signals. Using this strategy we have shown that cytokines can be expressed and targeted to different subcellular compartments (i.e. the cytoplasm, the endoplasmic reticulum and the nucleus), stored inside the cells and released after cell lysis as stable active proteins. Moreover, a plasma membrane targeted form of mGM-CSF displayed substantial amount of biological activity. These vectors could have potential applications in immunotherapy for tumours and DNA vaccination protocols.

Animals↗
PubMed2001

Proximal promoter of the murine syndecan-1 gene is not sufficient for the developmental pattern of syndecan expression in B lineage cells.

Syndecan-1 (CD138) is a cell membrane proteoglycan that binds extracellular matrix components and various growth factors. The role of syndecan-1 in the control of cell growth and morphology has been illustrated by its altered expression in hematological malignancies such as multiple myeloma as well as some solid tumors. It has been reported that the expression of syndecan-1 in cells of the B lineage is developmentally regulated such that pre-B cells and plasma cells express syndecan-1 while mature B cells do not. Thus, we investigated whether the proximal promoter region of the murine syndecan-1 promoter was able to confer the observed on-off-on expression of syndecan-1 in cells of the B lineage as they develop from pre-B cells to plasma cells. Experiments carried out using deletion mutants of the proximal promoter cloned upstream of the CAT reporter gene transfected into murine cell lines, representing the above stages of B-cell development, such as BA/F3 (pro-B cell), 70Z/3 (pre-B cell), 2PK3 (late mature B cell), and MPC-11 (plasma cell), showed detectable levels of CAT expression. The WEHI-231 (mature B cell) cell lines did not show detectable levels of CAT reporter activity. The strong levels of expression were observed with a fragment of the proximal promoter spanning the region from -365 to -95 (from the translation start point). However, Northern analysis of RNA obtained from the five murine B-cell lines, representing various stages of B-cell development, showed that the 70Z/3, MPC-11 but not BA/F3, and 2PK3 cells expressed detectable levels of syndecan-1 mRNA. By FACS analysis, using a rat anti mouse syndecan-1 antibody, syndecan-1 expression on the cell surface was found to correlate with the observed mRNA expression patterns in these cell lines. Our results indicate that the proximal promoter of the murine syndecan-1 promoter is not sufficient for the observed developmental pattern of syndecan expression in B cells.

Animals↗
PubMed2001

Broad spectrum of time of detection, primary symptoms and disease progression in infants with HIV-1 infection.

The relationship between time of HIV-1 detection, appearance of symptoms and disease progression was studied in all 24 HIV-1-infected infants from a cohort of 117 children who were born to HIV-1-infected mothers and monitored from birth. HIV isolation from plasma and mononuclear cells, HIV-1 DNA PCR (polymerase chain reaction) and, retrospectively, a quantitative assay for HIV-1 RNA were used for virus detection. Two infants possibly exhibited a symptomatic primary HIV infection. More children with than without symptoms during the first year of life progressed to immunological class 3 (P=0.013) and to AIDS or death (P=0.003) during follow-up. HIV-1 was detected within 4 days of age in 4 of 16 infants: 3 of them became symptomatic within 1 year, as did 6 of the remaining 12 infants (not statistically significant). All four infants in whom virus was detected within 4 days of age progressed to severe immunosuppression, compared to 6 of 14 in whom the virus detection test was initially negative prior to the first positive result (n.s.). Two children with previous repeatedly negative HIV detection tests were diagnosed with HIV-1 infection at 8 and 9 months, respectively. Repeated blood sampling is needed for the diagnosis of HIV-1 infection in perinatally exposed infants, and virus detection tests for exclusion of HIV-1 infection must be used with caution.

Acquired Immunodeficiency Syndrome↗
PubMed2001

High-dose chemotherapy and APSCT as a potential cure for relapsing hemolysing AILD.

Angioimmunoblastic lymphadenopathy with dysproteinemia (or dysgammaglobulinemia) (AILD) is a lymphoproliferative disorder with cytogenetic and molecular abnormalities characteristic of malignant T-cell lymphoma (angioimmunoblastic T-cell lymphoma -- AITL). We report the clinical course of a 58-year-old male patient with unusually aggressive AILD, including severe hemolysis and Guillain-Barré syndrome, who entered complete remission after CHOP therapy, but had a full relapse after 2 months. At relapse, treatment with high-dose chemotherapy followed by autologous peripheral stem cell transplantation (APSCT) with CD34 selected cells was shown to be successful. The patient is alive and disease-free 3 years after diagnosis and 32 months after APSCT. Considering the poor prognosis of the majority of patients with AILD, intensive treatment followed by APSCT, may be a subject for further studies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2001

A new method for in vitro expansion of cytotoxic human CD3-CD56+ natural killer cells.

Adoptive transfer of immunocompetent cells may induce anti-tumor effects in vivo. However, a significant obstacle to the development of successful cellular immunotherapy has been the availability of appropriate cytotoxic cells. Among the immunologic effector cells that are considered mediators of anti-tumor effects, those with the highest per-cell cytotoxic capacity express a natural killer (NK) cell phenotype, i.e., CD56(+)CD3(-). However, such cells are normally present only in low numbers in peripheral blood mononuclear cells (PBMCs), lymphokine activated killer (LAK), and cytokine induced killer (CIK) cell preparations. To optimize the expansion of human NK cells, PBMCs were cultured in different serum free medium supplemented with monoclonal anti-CD3 antibodies and interleukin (IL)-2 at varying concentrations. By using Cellgro stem cell growth medium supplemented with 5% human serum and IL-2 (500 U/ml) cells expanded 193-fold (median, range 21-277) after 21 days, and contained 55% (median, range 7-92) CD3(-)CD56(+) cells. The remaining cells were CD3(+) T cells, 22% (median, range 2-68) of which co-expressed CD56. The expanded cell population lysed 26 to 45% of K562 targets in a 1:1 effector to target ratio, signifying substantial cytotoxic efficacy. The described method is a simple and efficient way of expanding and enriching human NK cells. We have termed these high-yield CD3(-)CD56(+) cells cytokine-induced natural killer (CINK) cells.

CD3 Complex↗
PubMed2001

Effects of arsenic trioxide (As2O3) on leukemic cells from patients with non-M3 acute myelogenous leukemia: studies of cytotoxicity, apoptosis and the pattern of resistance.

Arsenic oxide (As2O3) has recently been reported to induce remission in a high percentage of patients with acute promyelocytic leukemia (APL). The aim of this study was to investigate the effects of As2O3 at therapeutic concentrations on cell viability and apoptosis on leukemic cells from patients with non-M3 acute myelogenous leukemia (AML) and to study the resistance profile compared to conventional AML drugs. Cells from 20 patients were exposed to therapeutic concentrations of As2O3 continuously for 96 h. As2O3 reduced the viability in blast cells from all the 20 tested patients compared to unexposed controls (p-value: 0.02 at 0.05 microM; <0.005 at 1.0 microM and higher concentrations). An increase in the apoptotic rate was also seen after incubation with As2O3. Parallel to the incubation with arsenic the in vitro sensitivity to a number of chemotherapeutic agents commonly used in AML was studied. Correlation coefficients for the in vitro sensitivity were highly significant between the conventional AML drugs except for Ara-C. For As2O3, all the correlation coefficients were negative and ranged between -0.05 and -0.51. Furthermore, increased P-gp expression in a multidrug resistant HL-60 cell line did not decrease the sensitivity to As2O3 as compared to the parental cell line. Neither did a P-gp-transfected variant of the K562 cell line show decreased sensitivity to As2O3. We conclude that As2O3 at therapeutic concentrations induces apoptosis and cytotoxic effects in blast cells from patients with non-M3 AML, and that As2O3 differs from conventional AML drugs with respect to the mechanisms that confer resistance to the drugs.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

Downregulation of bactericidal peptides in enteric infections: a novel immune escape mechanism with bacterial DNA as a potential regulator.

Antibacterial peptides are active defense components of innate immunity. Several studies confirm their importance at epithelial surfaces as immediate barrier effectors in preventing infection. Here we report that early in Shigella spp. infections, expression of the antibacterial peptides LL-37 and human beta-defensin-1 is reduced or turned off. The downregulation is detected in biopsies from patients with bacillary dysenteries and in Shigella- infected cell cultures of epithelial and monocyte origin. This downregulation of immediate defense effectors might promote bacterial adherence and invasion into host epithelium and could be an important virulence parameter. Analyses of bacterial molecules causing the downregulation indicate Shigella plasmid DNA as one mediator.

Adult↗
PubMed2001

In vivo nuclear delivery of oligonucleotides via hybridizing bifunctional peptides.

Linking proteins directly to nucleic acids has been a complex task. By hybridizing a bifunctional peptide nucleic acid (PNA) consisting of a nucleic acid binding moiety and a nuclear localization signal (NLS) we have previously demonstrated that it is possible to link protein functions directly to nucleic acids containing a PNA target site. By hybridizing fluorescently labeled oligonucleotides to PNA-NLS molecules and subsequently transfecting different organs in vivo we demonstrate an active nuclear translocation of the PNA-NLS/oligonucleotide complex in different mouse organs.

Animals↗