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T Lindmo

Publications and source records attributed to T Lindmo.

At least 37 records · Page 2Linked to original sources
PubMed1988

Relationship between changes in antigen expression and protein synthesis in human melanoma cells after hyperthermia and photodynamic treatment.

Hyperthermia and photoactivated hematoporphyrin derivative induce a dose-dependent reduction in the expression of the p250 surface melanoma-associated antigen on the human FME cell line. Expression of this glycoprotein antigen was quantitated by immunofluorescence flow cytometry based on the monoclonal antibody 9.2.27. Decrease in antigen expression was followed by a transient increase above the level for untreated cells, before normalization occurred about one week after treatment. These treatment-induced changes in antigen expression could partly be explained by changes in protein synthesis. This conclusion was based on the following observations: Hyperthermia and photoactivated hematoporphyrin derivative both inhibited protein synthesis. The latter increased again rapidly to rates above normal until antigen expression reached normal level, whereupon the protein synthesis rate decreased to normal. Inhibition of protein synthesis by cycloheximide 1 day after heating, prevented the recovery of antigen expression, demonstrating that protein synthesis is necessary for resumption of normal antigen expression. The changes in both antigen expression and protein synthesis were dose-dependent, and the magnitude and duration of the changes increased with increasing dose. The time courses of the changes in protein synthesis after two different treatments which both inactivated two logs of cells were almost identical, as were the time courses after two lower heat doses inactivating one log of cells. These similarities were reflected in the changes in antigen expression. At the same time as protein synthesis reached its maximum and antigen expression resumed normal level, an increase in the Golgi apparatus was observed ultrastructurally, indicating an increased synthesis rate and transportation of glycoproteins to the cell surface.

Antigens, Neoplasm↗
PubMed1988

Ploidy distribution in experimental liver carcinogenesis in mice.

There have been several reports on the distribution of DNA in premalignant and malignant liver cells after carcinogen treatment in rodents. The most striking result so far is that ploidy distributions seems to depend more on experimental protocols and less on carcinogenesis per se. The present study demonstrates that an evaluation by means of flow cytometry and stereological image analysis yields results showing similar ploidy distributions throughout the known sequence of tissue changes seen during liver cancer development. Furthermore, our results demonstrate inter-individual differences between the lesions in each of the steps in these tissue changes, (foci, nodules and hepatocarcinomas). The present study gives no reason to conclude that changes in ploidy distribution are essential in liver carcinogenesis.

Animals↗
PubMed1986

A method for determining ploidy distributions in liver tissue by stereological analysis of nuclear size calibrated by flow cytometric DNA analysis.

A method is presented for determining ploidy distributions in mouse liver from image analysis with stereological estimations of nuclear size in tissue sections. Nuclear profile distributions obtained from profile measurements were subjected to a mathematical unfolding procedure in order to obtain the nuclear size distributions. Based on the assumption that nuclear size increases monotonically with nuclear DNA content, flow cytometric DNA analysis of suspensions of liver cell nuclei was used to calibrate the method, thus yielding the mean nuclear size of each ploidy class, i.e., diploid, tetraploid, and octaploid nuclei. After the size interval for each of the ploidy classes was determined, the method allowed determination of ploidy distributions in mouse liver by stereological image analysis alone. The method was established from combined stereological and flow cytometric measurements on liver tissue representing two different stages of liver regeneration after two-thirds partial hepatectomy, and it was tested against an independent set of data representing a marked increase in the portion of S-phase cells.

Animals↗
PubMed1986

Selective cytotoxicity of 125I-labeled monoclonal antibody T101 in human malignant T cell lines.

The radiolabeled anti-T cell antibody T101 can be used for specific tumor localization, but unlabeled T101 produces limited cytotoxicity in patients. We thus studied the in vitro cytotoxic effects of T101 labeled with 125I, a radionuclide known for its short-range, high-linear-energy electrons. We showed that 125I-T101 could be readily prepared at high specific activity with high immunoreactivity. Human malignant T cell lines HUT 102, MOLT-4, and HUT 78 were found to differ in the number of T65 determinants (the antigen recognized by T101) and the sensitivity to external x-ray radiation, which were of significance for the cytotoxicity of 125I-T101 in vitro. The cytotoxic effects of 125I-T101 were also found to be dose dependent and increased with exposure time under frozen conditions. As controls, unlabeled T101 had no cytotoxic effect, while free Na 125I or the 125I-labeled irrelevant antibody 9.2.27 exerted minor cytotoxicity. In HUT 102 and MOLT-4, more than 3 logs' cell killing was achieved within four weeks. Because considerable cytotoxicity was demonstrated in vitro by 125I-T101 on T65-positive malignant cells, and because low-dose 111In-T101 can be used successfully for tumor localization, future trials using 125I-T101 at high specific radioactivity may improve therapeutic results in patients with T65-positive malignancies.

Antibodies, Monoclonal↗
PubMed1986

Changes in antigen expression on human FME melanoma cells after exposure to photoactivated hematoporphyrin derivative.

Exponentially growing melanoma cells of the line FME were incubated with hematoporphyrin derivative (HpD) for 1 and 18 h and subsequently exposed to light in the presence of HpD. Quantitative changes in the expression of the melanoma-associated surface antigen p250 recognized by the monoclonal antibody 9.2.27 were studied by flow cytometry. Treatment with HpD and light resulted in no immediate changes in the antigen expression. However, a few hours after light exposure a significant reduction in antigen expression was observed. For cells incubated with HpD for 1 h, the minimum expression of the antigen was observed 6 h after the irradiation, and the duration of the reduced expression was almost dose independent. On the other hand, the duration of the reduced antigen expression increased strongly with light dose for cells incubated with HpD for 18 h. In both cases antigen expression decreased exponentially with the product of drug concentration and light dose, indicating that there is no rapid mechanism by which the cells can repair the damage which leads to reduced antigen expression. Days were needed before the cells expressed a normal level of the antigen. A slight overshoot of the level of antigen expression above that for untreated cells was observed 2-5 days after light exposure depending on the incubation conditions with HpD and the light dose. At a given cell survival level (greater than 0.1), the decrease in antigen expression was more pronounced on cells incubated with HpD for 1 h than on cells incubated with the drug for 18 h.

Antigens, Neoplasm↗
PubMed1985

Differential of light-scattering detection in an arc-lamp-based epi-illumination flow cytometer.

Light-scattering histograms of blood cell suspensions were recorded for various ranges of scattering angles by means of an arc-lamp-based flow cytometer (AL-FCM). The results were compared with those obtained with a conventional, laser-based flow cytometer (L-FCM) with forward scattering (2-20 degrees) and scattering at right angles. Measuring with the AL-FCM in the angle range upward from 13 degrees, the relative light-scattering intensities of lymphocytes, monocytes, and granulocytes were essentially independent of scattering angle and closely similar to the values measured as right-angle scattering in the L-FCM. With a range of scattering angles upward from 2 degrees the AL-FCM yielded histograms similar although not identical to that of the forward-scattering detector in the L-FCM. Differentiation between live and dead cells in this mode of operation was similar in the two instruments.

Blood Cells↗
PubMed1985

Hyperthermia-induced changes in antigen expression on human FME melanoma cells.

Quantitative changes in the expression of three melanoma-associated antigens on human FME cells were studied by means of flow cytometry as a function of time after exposure to hyperthermia (42 degrees C for 1, 2, and 3 h; 43.5 degrees C for 1 and 2 h; 45 degrees C for 20 min). The expression of the three different surface antigens p250, p210, and p97a recognized by the monoclonal antibodies 9.2.27, 5.1, and 4.1, respectively, underwent qualitatively similar changes after hyperthermia. The antigen expression was reduced immediately after end of the treatment and decreased further to reach a minimum 1 day after treatment. Then the antigen expression gradually increased and reached a maximum above the level for unheated cells before it returned to this level about 1 wk after hyperthermia. The magnitude of these effects increased with increasing temperature and with increasing heating time at a given temperature. Quantitatively there were individual variations for the three different antigens. A positive correlation was found between the surviving fraction of the cells and the minimum level of antigen expression, indicating that different heat treatments which inactivated the same number of cells induced the same reduction in antigen expression. The demonstrated therapy-induced changes in antigen expression may be of importance for the use of monoclonal antibodies in diagnostic imaging of tumor tissue after hyperthermia or as therapeutic agents in combination treatments involving hyperthermia.

Antigens, Neoplasm↗
PubMed1985

Specific killing of human melanoma cells by 125I-labeled 9.2.27 monoclonal antibody.

The anti-melanoma antibody 9.2.27 localizes to melanoma cells when administered i.v. to melanoma patients, but high doses of this antibody alone have no specific cytotoxic effect in vivo. To determine whether radiolabeled antibodies would exhibit specific antimelanoma cytotoxicity in vitro, cell survival curves were established for NCl-N892 human melanoma cells treated with 125I-labeled 9.2.27 monoclonal antibody. The binding capacity per cell was 5 X 10(5) molecules of 9.2.27 immunoglobulin G, and the association constant of binding was 10(10) M-1. Antibody preparations with specific radioactivities of 9-80 microCi/micrograms were used. Colony-forming ability after in vitro exposure to 125I-9.2.27 was determined by a 1-h antibody incubation at saturating concentrations, washing, and cell freezing for various exposure durations. Colony survival was dose dependent, varying with the radioactivity per cell and the exposure time. The survival curves demonstrated no shoulder effect and had a 37% incremental survival dose of 0.5-0.9 X 10(5) decays/cell. Selective killing of melanoma cells was demonstrated in experiments where NCl-N417 lung cancer cells were mixed with the melanoma cells prior to antibody treatment. The NCl-N417 cells did not express the melanoma-associated antigen, were more sensitive to conventional external irradiation than were the melanoma cells, and could easily be distinguished from them by different growth morphology. In spite of a growth advantage for the melanoma cells in the clonogenic assay, the antigen-negative lung cancer cells selectively survived the treatment and were the only surviving cells after 15 days of exposure.

Antibodies, Monoclonal↗
PubMed1984

Stable quantitative differences of antigen expression in human melanoma cells isolated by flow cytometric cell sorting.

The stability of expression of a membrane antigen on human FME melanoma cells was investigated by means of flow cytometric cell sorting and analysis. The melanoma-associated 250 kd antigen was strongly expressed on all cells, as recognized by binding of the monoclonal antibody 9.2.27. By flow cytometric cell sorting, cells of high and low antigen expression were isolated, and the difference in antigen expression between the two populations was examined as a function of time in culture. Immediately after sorting, the median fluorescence intensities of the two populations differed by a factor of 2.7. After the first few days in culture, much of the range in antigen expression of the parent population was regenerated. However, a lasting difference in antigen expression was established, corresponding to 50% higher density of antigen on the cells sorted for high fluorescence intensity, compared to those sorted for low intensity. After trypsin treatment, which removed the antigen from the cell surface, normal antigen expression was regained after 2-3 days in culture, with the same difference between the two populations as before the trypsin treatment. The stability of the established difference in antigen expression between the two sorted subpopulations indicates that expression of this antigen is a precisely controlled, heritable characteristic of the FME melanoma cells.

Antibodies, Monoclonal↗
PubMed1984

Determination of the immunoreactive fraction of radiolabeled monoclonal antibodies by linear extrapolation to binding at infinite antigen excess.

Conjugates of monoclonal antibodies with radioactive isotopes, drugs or toxins have great potential for specific radiolocalization and inactivation of tumor cells. Because the conjugation procedure may adversely alter the antibody, quality control procedures must be applied to determine important characteristics of the conjugated antibody. One such property is how much of the conjugated antibody is able to bind to the relevant antigen. Based on theoretical considerations, we have developed a binding assay for radiolabeled monoclonal antibodies in which the fraction of immunoreactive antibody is determined by linear extrapolation to conditions representing infinite antigen excess. This ensures that the true value of the immunoreactive fraction is obtained, as opposed to the apparent immunoreactive fraction determined under conditions of limited antigen excess. The described assay is based on a double-inverse plot of the binding data which may be considered a modification of the Lineweaver-Burk plot. We established the method using 125I- and 111In-labeling of the 2 monoclonal antibodies T101 and 9.2.27 which currently are undergoing radioimaging trials at the National Cancer Institute. For properly performed conjugation procedures, immunoreactive fractions of about 0.9 were obtained, but a prolonged chloramine-T reaction for 125I-labeling resulted in an immunoreactive fraction of only 0.6. Due to its principle of determining binding at infinite antigen excess, the present method is quite insensitive to variation in the actual amounts of cells and antibody used, as well as the incubation time. We therefore recommend it as a quality control procedure for radiolabeled antibodies. Under certain conditions, this procedure is also applicable for quality control of drug- and toxin-conjugated monoclonal antibodies.

Antibodies, Monoclonal↗
PubMed1984

Antigen expression in human melanoma cells in relation to growth conditions and cell-cycle distribution.

The expression of a melanoma-associated antigen, recognized by the monoclonal antibody 9.2.27, has been studied in the human FME melanoma cell line, grown as a monolayer under various conditions in vitro and as tumours in athymic mice. Two-parameter flow cytometric measurements of DNA and immunofluorescence showed that the antigen expression was uniform throughout the cell cycle. Highest expression of the melanoma-associated antigen was found in cultures in which the medium was frequently renewed (4 times in 6 days) and no contact inhibition was present. In comparison, the antigen expression of cells subjected to medium starvation (6 days without medium renewal) was reduced to 44%, and the cell size, as measured by forward angle light scatter, to 82% of the values found for optimally growing cells. Intermediate conditions, such as scanty medium supply or contact inhibition of growth, gave smaller effects. Two-parameter measurements of cell size and immunofluorescence demonstrated a positive correlation between cell size and antigen expression. The reduction in cell size, therefore, could explain part, but not all, of the reduction in antigen expression on medium-starved and contact-inhibited cells. The antigen expression on FME cells grown as xenografts in athymic mice varied between individual tumours and was lower than on cells from optimal in vitro growth. Due to smaller cell size, the antigen density was, however, comparable to that on cells from optimal in vitro growth.

Animals↗
PubMed1983

Anomalous papillary carcinoma of the thyroid.

Most papillary carcinomas of the thyroid run a surprisingly indolent clinical course, and even widespread lymph node metastases in the neck are not a bad prognostic omen. A small group behaves in a far more aggressive fashion and kills through local invasion of adjacent structures or blood borne metastases. This paper deals with a papillary carcinoma which does not fit into any of these groups. Following hemithyroidectomy for papillary carcinoma in 1970 the patient, a woman aged 70 years, lived comfortably for nine years until she died of what appeared to be an unrelated cause. During these nine years, papillary carcinoma metastases were removed at irregular intervals from unusual locations such as the thoracic wall, both groins, and the thigh. Gross examination, light and electron microscopy, and freeze-etching, all failed to distinguish this tumor from conventional papillary carcinomas. Morphometry showed that the nuclei were significantly larger than those found in other papillary carcinomas, and conventional and flow cytometric DNA analysis proved that the primary tumor and the metastases contained mainly tetraploid cells. One lymph node metastasis had even larger nuclei than the others and also a different, bizarre DNA distribution pattern. This study also showed that the ground glass appearance of the nuclei of papillary thyroid carcinomas does not depend on hypodiploid DNA values. Of about 70 cases of papillary thyroid carcinomas in the world literature studied by conventional or flow cytometric DNA analysis, this case is the only one with tetraploid DNA values. It is therefore tempting to correlate this tetraploidy to its peculiar biologic behavior.

Aged↗
PubMed1983

Sézary cells with an unusual phenotype, their modulation with 12-O-tetradecanoyl phorbol-13-acetate (TPA) in vitro, and their relationship to T-cell development.

Leukemic cells from a patient with Sézary syndrome were studied with a panel of monoclonal antibodies. Despite their typical morphology, the cells expressed an unusual surface phenotype. They simultaneously expressed OKT4 and OKT8 reactivity, indicating a more immature origin of the neoplastic cells than what has previously been observed in Sézary syndrome, but they were OKT6 negative. In response to 12-O-tetradecanoyl phorbol-13-acetate (TPA) the cells underwent phenotypic alterations, as the OKT4 reactivity was significantly reduced and the OKT8 expression was retained. Thus, following TPA, the cells expressed a surface phenotype consistent with the cytotoxic/suppressor T-cell subset in normal peripheral blood. The findings are discussed in relation to normal T-cell maturation and differentiation processes.

Aged↗
PubMed1983

Progress through G1 and S in relation to net protein accumulation in human NHIK 3025 cells.

We have investigated whether human NHIK 3025 cells are dependent upon a net increase in cellular protein content in order to traverse G1 and S. The increase in DNA and protein content was studied by means of two-parameter flow cytometry using populations of cells synchronized by mitotic selection. By adding 1 microM cycloheximide to the medium protein synthesis was partially inhibited, resulting in negligible net accumulation of protein. The cells were able to enter S and progress through S under such conditions. The latter was the case whether the cells had been accumulating protein during G1 or not. The results further indicate that the larger cells enter S earlier and traverse S at a higher rate than the smaller cells. Our conclusion is that net accumulation of protein does not seem to be a prerequisite for traverse through G1 and S, i.e. DNA replication may be dissociated from the general growth of cell mass.

Cell Line↗
PubMed1983

Inhibition of cell-cycle progression by acute treatment with various degrees of hypoxia: modifications induced by low concentrations of misonidazole present during hypoxia.

The effect on cell-cycle progression in various phases of the cell cycle caused by an acute exposure to hypoxia in absence and presence of misonidazole (MISO) was investigated. Exponentially growing and synchronized cells of the human line NHIK 3025 were exposed to different degrees of hypoxia for a short period (1.5 or 3 h). The cell-cycle progression was studied both during and after hypoxia by flow-cytometric recording of DNA-histograms from treated and untreated cells. The rate of cell-cycle progression was reduced during hypoxia only if the O2-concentration was below 1000 ppm. The inhibition was phase specific with a strong effect in S (reduced DNA-synthesis), and a specific cell-cycle inhibition in late G1, probably at the G1/S-border. For cells inhibited (or arrested for extreme hypoxia) at the G1/S-border, the cell-cycle progression changed back to normal shortly after aerobic conditions were re-established. For cells rendered hypoxic and inhibited during S, hypoxia exerted a lasting effect expressed by a low cell-cycle progression rate even after aerobic conditions were re-established. This effect was strongly dependent on both the degree and the duration of the hypoxic treatment. The presence of a low concentration of MISO (0.05 mM) during hypoxia did not affect the cell-cycle progression during hypoxia at any O2-concentration. For cells rendered hypoxic during S, however, MISO (0.05 mM) counteracted the lasting effect of hypoxia for all concentrations of O2 where this lasting effect was observed.

Cell Cycle↗
PubMed1983

A flow cytometric DNA analysis of medullary thyroid carcinoma.

Flow cytometric DNA analysis of biopsy specimens from 10 patients with medullary carcinoma of the thyroid (MCT) was performed to evaluate the possible value of such data as indicators of the biologic behavior of these tumors. Some of the tumors had a unimodal distribution of nuclear DNA content, whereas others were bimodal. The mean modal DNA content in the cells of unimodal medullary carcinomas was not higher than that in the cells of thyroid parenchyma with a normal histologic appearance. This finding contradicts previous reports based on conventional cytophotometry. Bimodal DNA histograms were found in biopsy specimens from four patients, and the two patients with predominantly spindle-shaped cells belonged to this group. The total of nine biopsy specimens with bimodal DNA distributions were all from metastatic foci. Bimodal patterns were found, however, to co-exist with unimodal patterns, when several samples were examined from the same case. Bimodality or more severe aneuploidy did not seem to be related to shorter survival of the patients. The mean value of the percentage of cells in S-phase in our MCT series was higher than in follicular but lower than in anaplastic carcinomas. This fits well with clinical studies, where medullary carcinoma patients have been found to live longer than patients with follicular carcinomas but for a shorter time than those having anaplastic carcinomas.

Adult↗
PubMed1983

Delineation of subsets in human B-cell lymphomas by a set of monoclonal antibodies raised against B lymphoma cells.

Murine hybridoma antibodies to a human B-cell lymphoma were developed. After screening against normal T cells, monocytes, and granulocytes 11 antibodies that reacted with cells from other B-cell lymphomas remained, of which 10 showed individually distinct staining patterns, as tested by indirect fluorescence. When tested against lymphomas or cell lines, none of these antibodies revealed staining patterns suggesting reactivity with conventional B-cell surface markers, such as immunoglobulin, complement factor 3 receptors, or HLA-DR antigens. Only one of the antibodies (GB1) reacted with human serum, as determined by a blocking assay. The antibodies were found to belong to different immunoglobulin isotypes. Two antibodies (GB13 and GB14) reacted with greater than 5% of normal peripheral blood mononuclear cells. These reactions were mainly due to reactivity with B cells. The antibodies reacted only in a few cases with acute leukaemias, B-cell lines, and follicular lymphomas. On the other hand, distinct patterns of reactivity in different histological groups of diffuse lymphomas were obtained, suggesting that the antibodies may be useful in delineating phenotypic subsets among human B-cell lymphomas.

Animals↗