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K Nilsson

Publications and source records attributed to K Nilsson.

At least 91 records · Page 5Linked to original sources
PubMed1998

Summary report on the ISOBM TD-4 Workshop: analysis of 56 monoclonal antibodies against the MUC1 mucin. San Diego, Calif., November 17-23, 1996.

Sixteen research groups participated in the ISOBM TD-4 Workshop in which the reactivity and specificity of 56 monoclonal antibodies against the MUC1 mucin was investigated using a diverse panel of target antigens and MUC1 mucin-related synthetic peptides and glycopeptides. The majority of antibodies (34/56) defined epitopes located within the 20-amino acid tandem repeat sequence of the MUC1 mucin protein core. Of the remaining 22 antibodies, there was evidence for the involvement of carbohydrate residues in the epitopes for 16 antibodies. There was no obvious relationship between the type of immunogen and the specificity of each antibody. Synthetic peptides and glycopeptides were analyzed for their reactivity with each antibody either by assay of direct binding (e.g. by ELISA or BiaCore) or by determining the capacity of synthetic ligands to inhibit antibody binding interactions. There was good concordance between the research groups in identifying antibodies reactive with peptide epitopes within the MUC1 protein core. Epitope mapping tests were performed using the Pepscan analysis for antibody reactivity against overlapping synthetic peptides, and results were largely consistent between research groups. The dominant feature of epitopes within the MUC1 protein core was the presence, in full or part, of the hydrophilic sequence of PDTRAPAP. Carbohydrate epitopes were less easily characterized and the most useful reagents in this respect were defined oligosaccharides, rather than purified mucin preparations enriched in particular carbohydrate moieties. It was evident that carbohydrate residues were involved in many epitopes, by regulating epitope accessibility or masking determinants, or by stabilizing preferred conformations of peptide epitopes within the MUC1 protein core. Overall, the studies, highlight concordance between groups rather than exposing inconsistencies which gives added confidence to the results of analyses of the specificity of antimucin monoclonal antibodies.

Amino Acid Sequence↗
PubMed1998

Epitope characterization of MUC1 antibodies.

The specificities of the 56 MAbs submitted to the ISOBM TD-4 Workshop were characterized by ELISA assays against MUC1-positive (ZR75-1) and MUC1-negative cell lines (LS174T), binding to a 20-mer peptide corresponding to the tandem repeat region of MUC1 apoprotein, and Pepscan analysis of overlapping 9-mer peptides corresponding to the tandem repeat region of MUC1. The recognition of soluble MUC1 antigen from ZR75-1 cell line was also tested in two-site EIA using the ISOBM TD-4 MAb as catching MAb. The studies indicated that 35 of the submitted antibodies recognized epitopes expressed in the MUC1 tandem repeat region, and that 30 of these recognized epitopes within the immunodominant region (PDTRPAP) of the tandem repeat. Recognition of soluble MUC1 from ZR75-1 cell line indicated that additional 10 MAb recognized epitopes 'outside' the tandem repeat region of MUC1 from ZR75-1 cell line, or that the antibodies recognized epitopes depending on the glycosylation of the MUC1 tandem repeat. Six MAbs reacted only with the MUC1-negative cell line LS174T, and thus most likely did not recognize epitopes specific for MUC1.

Amino Acid Sequence↗
PubMed1998

Effects of exogenous stress protein 70 on the functional properties of human promonocytes through binding to cell surface and internalization.

The presence of antibodies against the major stress protein, Hsp70, in patients with autoimmune diseases led us to hypothesize that Hsp70 may occur extracellularly, and could exert chaperoning and regulatory effects on various cells. We examined the action of pure Hsp/Hsc70 on the main physiological functions of human promonocytic U-937 cells. The protein was isolated from calf muscle and was shown to be a mixture of inducible Hsp70 (60%) and constitutive Hsc70 (40%) isoforms. It was observed that the addition of the protein up-regulated two major monocyte/macrophage differentiation markers, CD11c and CD23, by 20-35%, while it had no effect on CD14. The experiments performed to investigate the influence of Hsp/Hsc70 on the reaction of U-937 cells to differentiation stimuli demonstrated that the addition of the protein prior to PMA was able to inhibit binding of proper transcription factors to double-symmetry and cAMP-response elements of the c-fos early response gene promoter. Administration of exogenous Hsp/Hsc70 prior to treatment with the tumor necrosis factor-alpha significantly lowered the number of apoptotic and necrotic cells. In no case did the control protein, ovalbumin, taken in the same concentration give a comparable effect on U-937 cells. Since the Hsp/Hsc70 effects occurred within the first hour of co-incubation, and therefore they might be explained by its interaction with the cell surface, we assayed binding of the biotinylated protein to U-937 cells by immunoenzyme assay, flow cytometry and indirect immunofluorescence. Using these three techniques we were able to detect Hsp/Hsc70 bound to cells after a 20 min incubation. According to flow cytometry data, at this time 32% of cells were positively stained with streptavidin-FITC. Immunofluorescence studies demonstrated Hsp/Hsc70 bound to the cell surface after a 20 min incubation followed by induction of patch and cap-like structures. One hour later, the majority of the protein had been internalized by U-937 cells.

Animals↗
PubMed1998

Distinct actions of Flt3 ligand and stem cell factor on myeloid lineage selection and maturation of granulocytes versus macrophages.

Flt3/Flk2 ligand (FL) and stem cell factor (SCF; c-kit ligand) interact with different but related surface receptor tyrosine kinases expressed on early hematopoietic cells. Both FL and SCF stimulate the proliferation of stem cells and progenitors, but the mechanisms by which these cytokines exert their functions are currently unknown. Here we show that FL and SCF have different effects on myeloid differentiation and lineage selection of early hematopoietic cells using a defined subpopulation of mouse bone marrow (BM) expressing c-Kit but lacking mature lineage markers (c-Kit+Lin-). SCF, together with IL-6, induced the differentiation of a large fraction of these progenitor cells toward mature granulocytes and to a lesser extent toward monocytes. In contrast, FL combined with IL-6 favored differentiation into mature monocytes and macrophages, and very few if any granulocytes could be identified. When FL and SCF were analyzed for their ability to support growth of multilineage erythroid colonies (pre-CFCmulti) and myeloid-committed colony-forming progenitors of granulocytes and monocytes (CFC-G/M), a clear discrepancy was also found. Both FL and SCF had synergistic effects on the proliferation of immature cells with blast-like morphology, but the expansion of pre-CFCmulti and CFC-G/M was favored by SCF but not by FL. FL synergized with both SCF and IL-6 with respect to proliferative response and maintenance of undifferentiated cells; however, the numbers of CFC-G/M after 7 or 14 days in culture were significantly lower than those observed with SCF combined with IL-6. Interestingly, in contrast to SCF, no pre-CFCmulti was recovered from BM cells expanded in the presence of FL and IL-6.

Animals↗
PubMed1997

Tissue factor expression in human monocytic cell lines.

Tissue factor (TF) is a main initiator of the coagulation protease cascade. Control of the expression of this protein in monocytes is essential, since these cells are the only circulating blood cells responsible for TF expression. In this report we have used two human cell lines, arrested at different stages of monocytic differentiation, to study TF expression. The monoblastic cell line U-937 had a constitutive expression of TF surface protein and low TF mRNA levels detected by immunofluorescence or quantitative reverse transcriptase polymerase chain reaction respectively. The phorbol-12-myristate-13-acetate (PMA) was a potent enhancer of TF expression in U-937. Lipopolysaccharide (LPS) and tumor necrosis factor (TNF) had no effect on TF expression in U-937. The Mono Mac 6 cell line, with phenotypic features similar to that of mature monocytes, expressed lower basal levels of TF mRNA and surface TF antigen. However, in Mono Mac 6 cells TF expression was induced in response to LPS and TNF. These results indicate differences in basal and induced TF expression between U-937 and Mono Mac 6 cell lines.

Carcinogens↗
PubMed1997

Retinoic acid receptor/retinoid X receptor heterodimers can be activated through both subunits providing a basis for synergistic transactivation and cellular differentiation.

The receptor for 9-cis-retinoic acid, retinoid X receptor (RXR), forms heterodimers with several nuclear receptors, including the receptor for all-trans-retinoic acid, RAR. Previous studies have shown that retinoic acid receptor can be activated in RAR/RXR heterodimers, whereas RXR is believed to be a silent co-factor. In this report we show that efficient growth arrest and differentiation of the human monocytic cell line U-937 require activation of both RAR and RXR. Also, we demonstrate that the allosteric inhibition of RXR is not obligatory and that RXR can be activated in the RAR/RXR heterodimer in the presence of RAR ligands. Remarkably, RXR inhibition by RAR can also be relieved by an RAR antagonist. Moreover, the dose response of RXR agonists differ between RXR homodimers and RAR/RXR heterodimers, indicating that these complexes are pharmacologically distinct. Finally, the AF2 activation domain of both subunits contribute to activation even if only one of the receptors is associated with ligand. Our data emphasize the importance of signaling through both subunits of a heterodimer in the physiological response to retinoids and show that the activity of RXR is dependent on both the identity and the ligand binding state of its partner.

Cell Differentiation↗
PubMed1997

Plasma methylmalonic acid in relation to serum cobalamin and plasma homocysteine in a psychogeriatric population and the effect of cobalamin treatment.

Cobalamin deficiency seems to be a relatively common condition in psychogeriatric patients. To elucidate the diagnostic possibility of cobalamin deficiency we have in this study analysed three markers for cobalamin deficiency, plasma methylmalonic acid, plasma homocysteine and serum cobalamin, in 96 psychogeriatric patients. Patients were divided into four groups according to serum cobalamins above or below 150 pmol/l and normal (< 19.9 mumol/l) or increased plasma homocysteine. The upper reference limit (95th percentile) for plasma methylmalonic acid in 100 healthy subjects was established to 0.42 mumol/l. The mean value of methylmalonic acid was increased only in the group of patients with serum cobalamin below 150 pmol/l and increased plasma homocysteine compared to the other groups. In this group six (46%) out of 13 patients exhibited increased plasma methylmalonic acid, whereas in the other groups the frequency of increased plasma methylmalonic acid only varied from 10 to 13%. During cobalamin supplementation the most pronounced decrease of plasma methylmalonic acid also occurred in the group of patients with low serum cobalamin levels and increased plasma homocysteine. Only 39% of the initial mean value for plasma methylmalonic acid was noted after 7-10 days of cobalamin administration.

Aged↗
PubMed1997

Human mast cells express functional TrkA and are a source of nerve growth factor.

Mast cells are the principal effector cells in IgE-dependent hypersensitivity reactions. Despite reports that rodent mast cells proliferate in the presence of nerve growth factor (NGF), human mast cells reportedly do not respond to this factor. To determine if human mast cells express the NGF receptors, TrkA tyrosine receptor and the low affinity NGF receptor (LNGFR), we first analyzed the mRNA expression by RT-PCR of TrkA and LNGFR in a human mast cell line (HMC-1) and in human mast cells cultured in the presence of stem cell factor. Both HMC-1 and cultured human mast cells were found to express TrkA but not LNGFR. TrkA protein was demonstrated by Western blot analysis of HMC-1 lysates. Using flow cytometric analysis and mast cell tryptase as a mast cell marker, both HMC-1 cells and cultured human mast cells were shown to coexpress tryptase and TrkA. Treatment of mast cells with NGF resulted in phosphorylation of TrkA on tyrosine residues as detected by immunoblotting with an antiphosphotyrosine antibody. Furthermore, NGF induced the immediate early gene c-fos in HMC-1 cells. HMC-1 cells and cultured human mast cells were also found to express NGF mRNA, and conditioned medium from HMC-1 cells stimulated neurite outgrowth from chicken embryonic sensory ganglia in culture. This effect was blocked by anti-NGF. Thus, mast cells express functional TrkA and synthesize NGF, suggesting a mechanism by which NGF may act as an autocrine factor for human mast cells, and by which mast cells and nerves may interact.

Cell Communication↗
PubMed1997

Cytotoxic activity of cyclosporin A and [3-keto-Bmt1]-[Val2]-cyclosporin (SDZ PSC 833) on tumour cells from patients with haematological malignancies.

OBJECTIVE AND METHOD: The fluorometric microculture cytotoxic assay was employed for characterisation of the cytotoxic effect of cyclosporin A (CsA) and its non-immunosuppressive analogue SDZ PSC 833, [3-keto-Bmt1]-[Val2]-cyclosporin (PSC) in tumour cells from patients with haematological or solid tumours. RESULTS: Tumour cells from patients with chronic lymphocytic leukemia (CLL) or non-Hodgkin's lymphoma (NHL) were found to be more sensitive to both drugs than those of tumour cells from patients with acute lymphocytic leukemia (ALL), acute myoblastic leukaemia (AML) and various solid tumours. There was a close correlation between the effects of the two drugs (correlation coefficient 0.71), but CsA was slightly more active than PSC in most diagnoses. No tumour cells sample showed sensitivity to PSC without also being sensitive to CsA. There was a moderate level of correlation between the activity pattern of CsA and doxorubicin (correlation coefficient 0.66), whereas the correlations with other cytostatics, such as vincristine, cytarabine and melphalan, were low (correlation coefficient -0.11 to 0.33). CONCLUSION: The results indicate that PSC shares the direct cytotoxic properties of CsA, but is slightly less potent. Clinical testing of the cytotoxic effect of these agents in haematological malignancies seems warranted and the apparent non-cross-resistance with standard agents makes cyclosporins a potentially useful adjunct to chemotherapy in those diagnoses.

Antineoplastic Agents↗
PubMed1997

Antigenic determinants of prostate-specific antigen (PSA) and development of assays specific for different forms of PSA.

Monoclonal antibodies were raised against prostate-specific antigen (PSA) by immunization with purified free PSA, i.e. not in complex with any protease inhibitor (F-PSA) and PSA in complex with alpha1-anti-chymotrypsin (PSA-ACT). Epitope mapping of PSA using the established monoclonal antibody revealed a complex pattern of independent and partly overlapping antigenic domains in the PSA molecule. Four independent antigenic domains and at least three partly overlapping domains were exposed both in F-PSA and in the PSA-ACT complex, while one antigenic domain was specific for F-PSA. The different domains contained both continuous and discontinuous epitopes. The combination of antibodies recognizing antigenic domains exposed both in F-PSA and PSA-ACT made it possible to develop several highly sensitive sandwich immunoassays for determination of total PSA, i.e. F-PSA + PSA-ACT, with the same molar response for F-PSA and PSA-ACT. Assays specific for F-PSA (cross-reactivity between F-PSA and PSA-ACT < 1%) were developed by the combination of antibodies recognizing epitopes exposed only in F-PSA and antibodies recognizing epitopes exposed both in F-PSA and PSA-ACT.

Animals↗
PubMed1997

Interleukin-15 + thioredoxin induce DNA synthesis in B-chronic lymphocytic leukemia cells but not in normal B cells.

We have previously shown that Staphylococcus aureus Cowan strain 1 particles (SAC) + thioredoxin (Trx) + IL-2 may induce B-chronic lymphocytic leukemia (B-CLL) cells to proliferate. In this paper we have examined IL-15, which has activities similar to IL-2, for its ability to stimulate B-CLL cells and compared its activity with that of IL-2. We found that B-CLL cells could be induced to DNA synthesis upon treatment with IL-15 + Trx. The presence of Trx was essential for the IL-15-induced DNA synthesis. This contrasts to the effect of IL-15 + Trx on normal CD5+ and CD5- B cells, where IL-15 + Trx alone only induced limited DNA synthesis. IL-15 was as effective in the induction of DNA synthesis in B-CLL cells as IL-2, but about 100-fold less potent with an EC50 of 200 ng/ml. In addition we found that the IL-15 + Trx-induced proliferation was inhibited by CD40 stimulation. We conclude that IL-15 together with a proper costimulus can induce B-CLL cells to proliferate in vitro.

B-Lymphocytes↗
PubMed1997

The effects on growth and survival of IL-6 can be dissociated in the U-266-1970/U-266-1984 and HL407E/HL407L human multiple myeloma cell lines.

Several studies have documented IL-6-dependent growth promotion of murine and human neoplastic plasma cells. However, it is well known that human multiple myeloma (MM) cells in vitro show a considerable degree of heterogeneity concerning growth and survival requirements. This heterogeneity, which probably reflects overlapping effects of feeder cells, interleukin 6 (IL-6) and components of fetal calf serum (FCS) as well as tumour heterogeneity in vivo, has hampered the elucidation of molecular mechanisms underlying the effects of IL-6. In an attempt to dissociate growth and survival promotion of IL-6, we have studied two pairs of human MM cell lines, HL407E/HL407L and U-266-1970/U-266-1984, selected to represent different stages of in vitro tumour progression and dependence of feeder cells and exogenous IL-6. We demonstrated that exogenous IL-6, in the presence of FCS, conveyed: (a) a strong growth stimulatory effect with weak or no survival promotion in HL407L and U-266-1970 cells; (b) promotion of survival with no effects on growth in HL407E cells; (c) no growth or survival promotion to U-266-1984. Moreover, our results suggested that IL-6 may enhance apoptosis in U-266-1970/U-266-1984 cells, and that FCS may interfere with IL-6 in its growth stimulatory effect. The relative dissociation of growth, survival and apoptotic effects of IL-6 leads to the conclusion that the HL407E/HL407L and U-266-1970/U-266-1984 pairs of cell lines provide a useful human model system to study molecular mechanisms underlying these separate events.

Apoptosis↗
PubMed1997

Pulmonary clearance of [99mTc]DTPA and [99mTc]albumin in smokers.

We measured the pulmonary clearance of [99mTc]DTPA and [99mTc]albumin for 3 h in 10 non-smokers and 10 healthy smokers. Seven of the non-smokers had a monoexponential clearance of [99mTc]DTPA with a mean half-life of 66 +/- 18 min. The other three had a biexponential clearance of [99mTc]DTPA with a fraction of radio-activity clearing rapidly (fF) of 14 +/- 4%. Eight smokers had biexponential clearance of [99mTc]DTPA. The half-life of the fast and slow clearance components was 12 +/- 5 and 62 +/- 11 min respectively. The fF was 56 +/- 25%. Two of the smokers showed a monoexponential clearance of [99mTc]DTPA with a half-life of 72 and 55 min. All non-smokers had monoexponential clearance curves for [99mTc]albumin, compared with seven smokers. The half-life was 279 +/- 43 min in non-smokers and 236 +/- 64 min in smokers. The difference in half-life was not significant. In three smokers, the clearance curves of [99mTc]albumin were significantly better described by a bi-exponential equation. The fF was 22 +/- 9%. The effects of smoking on the clearance of [99mTc] albumin appear to be qualitatively similar to those on the clearance of [99mTc]DTPA. Clearance of [99mTc]albumin seems less sensitive to the effects of smoking than clearance of [99mTc]DTPA.

Adult↗
PubMed1997

CD40 ligation inhibits IL-2 and SAC+IL-2 induced proliferation in chronic lymphocytic leukaemia cells.

This paper reports on differences between B cell-type chronic lymphocytic leukaemia (B-CLL) and normal B cells in their response to IL-2+thioredoxin (Trx), Staphylococcus aureus Cowan strain 1 (SAC)+IL-2+Trx, and to CD40 ligation of IL-2+Trx and SAC+IL-2+Trx stimulation. The authors found that Trx acted synergistically with IL-2 and SAC+IL-2 in inducing DNA synthesis in B-CLL cells, but not in the normal B cells. Interestingly, IL-2+Trx alone was found to induce proliferation in B-CLL cells from patients with advanced stages of disease. In addition, we also found that IL-2+Trx and SAC+IL-2+Trx-induced DNA synthesis of B-CLL cells was inhibited by CD40 activation (by soluble anti-CD40 MoAb and anti-CD40 MoAb presented on irradiated CD32L cells). In clear contrast, SAC+IL-2+ Trx-induced DNA synthesis of normal B cells was not inhibited by soluble anti-CD40 MoAb. The authors therefore conclude that B-CLL cells differ from normal B cells in their response to IL-2 (IL-2+Trx) and CD40 ligation.

Adult↗
PubMed1997

Pulmonary clearance of 99mTc-DTPA in experimental surfactant dysfunction treated with surfactant instillation.

BACKGROUND: Breakdown of the alveolo-capillary barrier is a characteristic feature of respiratory distress syndrome. Restoration of alveolo-capillary barrier function may be an important aspect of surfactant replacement therapy. We examined the effect of surfactant instillation on alveolo-capillary barrier function in an experimental model of surfactant dysfunction by measuring pulmonary clearance of 99mTc-DTPA. METHODS: Nineteen rabbits were tracheotomized and mechanically ventilated. Surfactant dysfunction was induced by administration of a synthetic detergent in aerosol form. Detergent was given to 13 rabbits; seven rabbits were then treated with instillation of natural surfactant, whereas six rabbits received saline. Six rabbits were used as untreated controls. An aerosol of 99mTc-DTPA was administered to all animals and the pulmonary clearance was measured with a gamma camera. RESULTS: 99mTc-DTPA cleared from the lungs with a half-life of 71 +/- 22 min in the control animals, 21.4 +/- 7.4 min in the surfactant-treated animals and 5.8 +/- 1.5 min in the saline-treated animals. The difference in half-life between groups was highly significant (P < 0.001). There was no change in arterial oxygenation or compliance in controls or in animals treated with saline. In animals treated with surfactant, a small transient reduction in arterial oxygen tension and a more long-standing reduction in compliance were observed. CONCLUSION: Surfactant treatment thus significantly attenuated the effect of detergent treatment but did not restore alveolo-capillary transfer of 99mTc-DTPA to normal.

Animals↗
PubMed1997

Characterization of a spotted fever group Rickettsia from Ixodes ricinus ticks in Sweden.

A spotted fever group rickettsia isolated from the common tick, Ixodes ricinus, was genetically characterized by PCR and genomic sequencing. This study was performed with nymphal and adult ticks collected in southern and central Sweden. I. ricinus is the only North European tick species of medical importance which is regularly collected from humans. No species of the genus Rickettsia has previously been found in Scandinavian ticks, nor has any case of domestic rickettsial infection in humans or animals been reported. According to the nucleotide sequencing, the present Rickettsia sp. belongs to the spotted fever group of rickettsiae. Ticks are the most common arthropod reservoirs and vectors of the rickettsiae of this group. Among 748 ticks investigated, 13 (1.7%) were positive for a Rickettsia sp. Borrelia burgdorferi was detected in 52 (7%) of the ticks, a prevalence similar to or somewhat lower than that previously been recorded in other Swedish studies. There was no evidence of ehrlichial or chlamydial DNA in these ticks. The Rickettsia sp. was further characterized by 16S ribosomal DNA (rDNA) sequencing and restriction fragment length polymorphism (RFLP). The 16S rDNA sequencing resulted in a sequence identical to that described for Rickettsia helvetica, but the pattern obtained with RFLP of the citrate synthetase gene diverged from previously known patterns. The rickettsial agent of one tick which was positive by PCR was confirmed by transmission electron microscopy. The morphology of this rickettsia was similar to that of the spotted fever and typhus group rickettsiae. This represents the first documented isolate of a Rickettsia sp. from Swedish ticks.

Animals↗