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At least 577 records · Page 32Linked to original sources
PubMed1997

Use of a membrane-localized green fluorescent protein allows simultaneous identification of transfected cells and cell cycle analysis by flow cytometry.

The simultaneous detection of the green fluorescent protein (GFP) and DNA content using propidium iodide (PI) by flow cytometry is made difficult because of the unique nature of these 2 fluorogenic reagents. For PI to enter cells efficiently and to stain DNA quantitatively, the cells must first be permeabilized; ethanol treatment is a routine method to achieve this. However, this permeabilization step causes GFP, which is normally found in the cytoplasm, to leach out of the cells. Although the use of paraformaldehyde-based fixatives allows GFP to be maintained in cells and retain its fluorescence even after ethanol permeabilization, the protocol we commonly employ results in inefficient PI staining and poor quality DNA histograms. To circumvent these difficulties, we have employed a GFP-fusion protein which localizes to the cellular membrane and as such is retained in cells upon ethanol permeabilization without prior fixation. This allows the GFP signal to be detected in cells treated with ethanol in preparation for PI staining and cell cycle analysis. This property facilitates the use of GFP as a marker for transfected cells in experiments designed to characterize the effects of ectopic expression of cellular or viral genes on cell cycle progression.

Biomarkers↗
PubMed1997

1-NGFR receptor is a new flow cytometric tool for rapid cell cycle-correlated gene therapy complementation studies in viable cells.

Control of successful genetic complementation of cellular defects in heterogenous cell populations requires biochemical selection markers or cell analytical specifiers. With available gene therapy technologies, only a fraction of a cell population is transfected or transduced. We applied and optimized a novel dual-laser flow cytometric technique to analyze immediately the genetic complementation of cells dysregulated in cell proliferation and DNA repair. A novel bicistronic retrovirus carrying the normal Fanconi anemia gene (group C) and the cell surface marker gene l-NGFR was constructed to analyze the normalization of the G2-phase cell cycle defect in DNA-repair-deficient FA(C) lymphoblastoid cells after transduction. Using a dual-laser multiparameter technology, we 1) analyzed the cell-cycle distribution of viable/dead cells using Hoechst 33342 (with ultraviolet light), 2) identified the genetically complemented cells by FITC antibody labeling of the novel l-NGFR surface marker (488 nm), and 3) recorded mitomycin C-induced cell death in nontransduced and transduced cells by propidium iodide. Artificial l-NGFR expression is high and similar in ontogenetically and phylogenetically different cell populations. With this novel l-NGFR marker technology, the success of gene therapy of cell-cycle dysregulation in even small subpopulations of cells can be recorded within 48 h. In addition to improved cell analysis, l-NGFR surface marker expression can also be used for rapid generation of pure cell populations by column cell separation technologies.

Antibiotics, Antineoplastic↗
PubMed1998

Flow cytometric assessment of cell structural and functional changes induced by acetic acid in the yeasts Zygosaccharomyces bailii and Saccharomyces cerevisiae.

Flow cytometry (FCM) was used with different viability dyes to assess changes in cell structure and function induced by acetic acid (AA) in populations of Zygosaccharomyces bailii (AA resistant) and Saccharomyces cerevisiae (AA sensitive). Kinetic changes in esterase activity, intracellular dye processing, and membrane integrity were monitored, and to detect those changes we used three assays involving fluorescein diacetate hydrolysis, FUN-1 processing, and propidium iodide exclusion, respectively. In S. cerevisiae, the decrease in the ability to process FUN-1 preceded the decrease in esterase activity, and there was loss of cell membrane integrity after incubation with AA. In Z. bailii, with higher AA concentrations, there was a similar decrease in the ability to process FUN-1, which also preceded the loss of cell membrane integrity. Changes in esterase activity in this yeast induced by AA treatment could not be monitored because the changes occurred independently of the presence of the acid. For control samples (untreated cells killed with 10% v/v of AA), the percentages of nonaltered cells as estimated by FCM and percentages of viable cells as estimated by colony forming unit (CFU) counts were identical. However, for cell samples treated for short periods with 3% (v/v) or less of AA, none of the dyes produced FCM results comparable to those produced by CFU counts.

Acetic Acid↗
PubMed1998

Detection of eosinophils in whole blood samples by flow cytometry.

A flow cytometric method to detect and study human eosinophils in whole blood was established. Normal subjects and patients with various types of eosinophilia (hypereosinophilic syndromes, allergic diseases, dermatitis, Hodgkin's Disease, parasitosis) were studied. Whole blood samples were treated for 10 minutes at room temperature with a commercially available reagent (FACS Lysing Solution, Becton Dickinson) which acts both as a fixative and as a lysing agent. Eosinophils were identified as a granulocytic subpopulation with higher SSC and FSC properties. This cell population was characterized by evident autofluorescence and hypodiploid DNA features after propidium iodide staining. The purity of the eosinophil population sorted after electronic gating was close to 100%. A very significant correlation between eosinophil counting by our whole blood method and other two assays, namely routine automatic counting by the H*3 Bayer System and eosinophil detection by depolarized SSC, was obtained. The phagocytic properties of eosinophils were also studied by means of a commercially available diagnostic kit, thus demonstrating that our method is also suitable for the study of those granulocytic functions which can be evaluated by flow cytometry.

Adolescent↗
PubMed1999

Heat pretreatment increases resolution in DNA flow cytometry of paraffin-embedded tumor tissue.

BACKGROUND: Flow cytometry of single-cell suspensions prepared by enzymatic digestion from formalin-fixed, paraffin-embedded tissue suffers from several major drawbacks. The most important factors that influence the results are the high and unpredictable coefficients of variation (CVs) of the G0/G1 peak in the DNA histogram and reduction of propidium iodide (PI) intercalation with DNA, resulting from protein cross-linking by formalin. METHODS: In this study we introduce a heating step (2 h incubation in citrate solution at 80 degrees C) prior to a brief pepsin digestion of tissue sections in the protocol for DNA content analysis of formalin-fixed and paraffin-embedded tissue. This new method is compared with established methods for the preparation of cell suspensions from frozen and paraffin-embedded tissues with respect to cell yield, DNA histogram resolution, DNA dye saturation kinetics, cell cycle parameters, and antigen retrieval in various epithelial and nonepithelial tissues. RESULTS: The recovery of single cells from the paraffin sections was doubled by the heat treatment step, while the limited time of proteolysis resulted in decreased cell debris. Furthermore, an increased fraction of cells became cytokeratin-positive, while these immunocytochemically stained cells also exhibited a higher mean fluorescence intensity. The DNA histograms prepared from cell suspensions obtained according to this new protocol showed a significantly improved resolution, leading to a better identification of peridiploid cell populations. Heat pretreatment of paraffin-embedded archival tissue sections showed PI saturation kinetics similar to, or even better than, those of fresh unfixed tissues, independent of duration of fixation. CONCLUSIONS: This new method, making use of routinely available antigen retrieval principles, thus allows high-resolution DNA analysis of routinely fixed and paraffin-embedded tissue samples. Using external reference cells, inter- and intralaboratory standardization of DNA histograms can be achieved.

Breast Neoplasms↗
PubMed1999

Flow cytometric analysis of estrogen receptor expression in isolated nuclei and cells from mammary cancer tissues.

BACKGROUND: Cellular expression of receptors for the hormones estrogen and progesterone in human mammary tumors is of diagnostic and prognostic value. Ligand binding assays have been replaced by immunohistochemical analysis of receptor expression. However, both of these techniques are slow, and in the ligand-binding assay it is difficult to measure heterogeneity of receptor expression in individual cells. Flow cytometry has been used extensively for monitoring the expression of cellular receptors in hematopoietic tumors but has been of limited value in the analysis of mammary tumors, which are difficult to disaggregate into single cells for flow analysis. Hormone receptors have a predominant nuclear localization, and it is relatively easy to isolate nuclei from paraffin-embedded archival tissues for flow cytometric analysis of receptor expression. METHODS: Thick sections from formalin-fixed paraffin-embedded archival mammary tumors were digested by different enzyme solutions for the isolation of single nuclei. Different fixatives were used to compare the results on subsequent staining of the nuclei for estrogen receptor (ER) expression. Double staining with propidium iodide and fluorescein isothiocyanate labeled secondary antibodies for ER expression was used for multiparametric analysis of ER and DNA content. RESULTS: Digestion of paraffin sections with low concentration of pepsin and detergents was ideal for isolation of single nuclei. Fixation with paraformaldehyde in the presence of Triton X-100 improved staining of the cells. Isolated nuclei had enhanced immunoreactivity compared with the whole cells, and subpopulations differing in reactivity could be identified in the nuclear fractions. Double staining of nuclei for ER expression and DNA content could allow for multiparametric analysis of these two important parameters. CONCLUSIONS: The procedures described can be used for processing of archival paraffin-embedded mammary tumors for monitoring of ER expression and aneuploidy. These two parameters have important diagnostic and prognostic significance in mammary tumors. Laser flow cytometry by providing multiparametric analysis can allow for correlation of these cellular markers with other important cellular and clinical parameters.

Breast Neoplasms↗
PubMed1999

Analysis with flow cytometry of green fluorescent protein expression in leukemic cells.

BACKGROUND: The measurement of DNA content with propidium iodide (PI) in cells transfected with expression vectors encoding the green fluorescent protein (GFP) is a useful tool in studying a variety of biological functions of proteins within cells. The purpose of this study was to determine conditions of formaldehyde fixation that permit intracellular GFP fluorescence and adequate DNA histograms to be generated following transient transfection of cells with a GFP-encoding plasmid. Cell cycle analysis was also performed in GFP-positive cells. METHODS: The murine myeloid leukemic cell line, 32Dcl3, was used as the model system. Cells were transfected with a GFP-encoding plasmid (pEGFPC1). Following fixation in different formaldehyde concentrations and permeabilization with 70% ethanol, cells were stained with PI and analyzed by flow cytometry for GFP fluorescence and DNA content. Transfected cells were also analyzed for GFP fluorescence and DNA content following release from nocodazole block. RESULTS: Fixing cells in 0.51-1.75% formaldehyde concentrations prior to ethanol permeabilization resulted in 14-19% of transfected cells being GFP-positive, with acceptable coefficients of variation on the G(1) peak of DNA histograms. Analysis of cells synchronized to and released from the G(2)-M phase by nocodazole suggested that GFP-positive cells, when compared to GFP-negative cells, did not appear to progress out of G(2)-M following release from nocodazole block. Simultaneous detection of GFP fluorescence and DNA content by PI staining is possible following transient transfection of cells with a single expression vector encoding GFP. Our results demonstrate that GFP expression can be detected, using flow cytometry to perform cell cycle analysis in murine leukemic cells.

Animals↗
PubMed1999

Comparative analysis of apoptosis in HL60 detected by annexin-V and fluorescein-diacetate.

BACKGROUND: Our aim was to compare and evaluate apoptosis formation as detected by propidium-iodide (PI)/annexin-V or PI/fluorescein-diacetate (FDA) as dose-response parameters in a human promyelocytic leukemia cell line, HL60. METHODS: In exponentially growing HL60 cells, apoptosis was induced by ionizing radiation, hyperthermia, topotecan, and cytosine beta-D-arabinofuranoside. At 4 consecutive days following induction, apoptosis was detected by double-labelling, either with PI/annexin-V or PI/FDA. Forward and side scatter, red (PI), and green (FDA or annexin-V) fluorescence were measured by flow cytometry. RESULTS: While light scatter discriminated between morphologically damaged and undamaged cells, fluorescence differentiated vital, apoptotic, and dead cells. Equal proportions of these three subpopulations were detected by both staining techniques. Occasionally, early and mature apoptoses were identified as distinct clusters. During the 4-day observation period, no pronounced maxima of the apoptotic fractions were obtained with either treatment modality. The gradual increases usually showed a delay of 1-2 days. CONCLUSIONS: FDA and annexin-V are equally suitable for detecting apoptosis. Separation improves with time after induction, indicating that, with respect to test specificity, mature apoptoses are superior to early stages. However, the sensitivity towards low rates of apoptosis after weak induction appears limited with both staining procedures.

Annexin A5↗
PubMed2000

Comparison of DiOC(6)(3) uptake and annexin V labeling for quantification of apoptosis in leukemia cells and non-malignant T lymphocytes from children.

Early during apoptosis, there is a reduction in mitochondrial transmembrane potential (MTP) and externalization of phosphatidylserine (PS) in cell membrane prior to eventual cell death. Flow cytometric detection techniques targeting these changes, reduction of DiOC(6)(3) uptake upon the collapse of MTP and annexin V binding to PS have been successfully used to detect apoptotic cells. These methods have given comparable results when cell lines were used. We compared the two different techniques, DiOC(6)(3) uptake and Annexin V-propidium iodide co-labeling in the quantification of cytarabine, vincristine and daunorubicin induced apoptosis on three leukemia cell lines (HL-60, CEM, U937), and bone marrow blasts from 26 children with acute myeloid leukemia, 14 with T cell acute lymphoblastic leukemia. Anti-Fas-induced apoptosis in culture-grown peripheral blood T lymphocytes on 18 samples from 9 children with non-malignant conditions were also studied by these techniques. Our results showed that there is a correlation (P < 0. 05) between the apoptosis rates measured by these two techniques for drug-induced apoptosis in myeloid and lymphoid blasts, and for anti-Fas mAb-induced apoptosis in T lymphocytes. This data suggests that reduction of the MTP and PS externalization may be common to many apoptotic pathways and techniques targeting either of these changes may be used in quantification of apoptosis in different clinical samples.

Annexin A5↗
PubMed2000

Analysis of apoptosis of lymphoid cells in fish exposed to immunotoxic compounds.

BACKGROUND: Chemical induction of apoptosis in cells is believed to contribute to toxicity. Techniques for measuring apoptosis have increased in both sensitivity and number and in many cases can be readily extended to nontraditional research species. A comparison of established assays for measuring apoptosis of lymphoid cells has thus far not been performed in the fish and thus would be efficacious in assessing immunotoxicity. METHODS: The present study evaluated chemical-induced immune cell apoptosis in fish (tilapia, Oreochromis niloticus) exposed to two known immunotoxic chemicals, azathioprine and T-2 toxin. Cytocentrifugation and light microscopy of leukocyte-enriched cell samples from the pronephros (i.e., the fish primary hematopoietic compartment) demonstrated chemical-related increases in apoptotic bodies. This observation was examined further with the ApoAlert Annexin V Apoptosis kit and two DNA-binding dyes employed for detecting apoptosis, 7-aminoactinomycin D (7-AAD) and propidium iodide (PI). RESULTS: The apoptotic probes confirmed the microscopic observations of increased apoptosis in the chemical-exposed fish. The ApoAlerttrade mark annexin V and 7-AAD assays, which discriminate early and late apoptosis/necrosis, compared well in identifying apoptotic populations. PI staining in Vindelov's solution was unable to detect early apoptosis. CONCLUSIONS: The present data suggest that apoptotic immune cells may be a useful marker for certain immunotoxicant exposures in fish. These findings agree with those of previous reports that fish may respond immunologically in a manner similar to mammals after immunotoxicant challenge.

Animals↗
PubMed2000

Confocal multilaser focusing and single-laser characterization of ultraviolet excitable stains of cellular preparations.

BACKGROUND: The aims of this study were (1) to realign cellular preparations when spots and structures are excited by different lasers of a confocal laser scanning microscope (multilaser studies); (2) to avoid the use of realigment methods by selecting fluorochromes that can be excited by only one laser (single-laser experiments). METHODS: In multilaser studies, we used propidium iodide fluorescent beads, as well as tetramethyl rhodamine isothiocyanate (TRITC), fluorescein isothiocyanate (FITC), and 4'-6 diamidino-2-phenylindole (DAPI)-stained human cancer lines. They were excited using HeNe, argon, and ultraviolet (UV) argon laser lines of a confocal laser scanning microscope. Single-laser experiments using UV excitation only were performed using europium as a model for magnetic resonance paramagnetic contrast agents. Nuclei of human cancer lines and tissue were counterstained by DAPI and cytoplasms were labeled with ELF-97 substrates. Factor analysis of medical images (FAMIS) and correlation methods were used to realign shifted images, focus images, and characterize each fluorochrome when necessary. RESULTS: In multilaser studies, superimposition of factor images corrected Z shifts and correlation methods provided X, Y correction values. In single-laser experiments, each fluorochrome was clearly distinguished in the group of fluorochromes. Estimated images in both studies showed colocalizations of structures. CONCLUSIONS: It is possible to characterize differences in the focus and alignment of fluorescent probes and to correct them. It is also possible to study colocalization of UV excitable fluorochromes (DAPI, ELF-97, europium) in cellular and tissular preparations via multilaser or single-laser experiments.

Europium↗
PubMed1996

Assessment of metal extract toxicity on human lymphocytes cultured in vitro.

In this study the toxic effects of chromium, nickel, and cobalt extracts on in vitro cultured lymphocytes were evaluated. Graphite furnace atomic absorption spectrometry was used to measure the ion concentration. After serial dilution of the extracts, the viability of lymphocytes at 24, 48, and 72 h was estimated by flow cytometry, including propidium iodide staining and light scatter property assessment, and by MTT reduction test. The results of the investigation allowed us to conclude that 1) standardization of the procedure for preparing extracts is fundamental to obtaining repeatability of results; 2) the toxicity of an extract cannot be evaluated with a single viability assay; a combination of functional and structural tests is required; 3) when methods based on enzymatic reactions are performed, e.g. MTT test, it is advisable to replace the extract containing metal ions with fresh medium in order to avoid any interference with viability testing; 4) the amount of Co and Ni in the extract is similar, but the Cr release is very poor; 5) the lower toxicity of Cr extract probably is due to the lower ion concentration; 6) the assessment of 50% cytotoxic concentration (TC50) allows quantification of materials toxicity and comparison of various metals; and 7) the determination of a noncytotoxic concentration, i.e., a concentration lower than TC10, is required for subsequent investigation of cell functions because such studies can be carried out only on viable cell population.

Cell Survival↗
PubMed1998

False positive results in cytotoxicity testing due to unexpectedly volatile compounds.

We investigated the cytotoxicity of different dental materials according to the study protocol adopted by our lab for the screening of new materials. Experimental parameters used in such testing are addressed mainly in documents EN 30993 "Biological evaluation of medical devices, Part 5: Tests for cytotoxicity: in vitro methods" and "Biological evaluation of medical devices, Part 12: Sample preparation and reference materials." Cells were cultured in microplates and challenged with aqueous extracts of the materials. The assay methods were neutral red- and propidium iodide-uptake assays, both indicative of cell viability and able to provide quantitative data. The observation of contrasting results for one material using the above-mentioned methods raised some concern about the assay system used. With further experimentation, it appeared that a sustained release of volatile substances still present in one extract exerted a toxic effect in neighboring cultures. It is concluded that in the microenvironment of a microplate the distribution of samples cannot be disregarded, as it may be responsible for toxicity cross-contamination. Moreover, the use of more than one single method has to be recommended in cytotoxicity testing, in order to avoid false positive results due to experimental artifacts.

Animals↗
PubMed1998

Cytotoxicity testing of materials with limited in vivo exposure is affected by the duration of cell-material contact.

Silicones for dental impression largely are used to record the geometry of hard and soft dental tissues. They are considered to be medical devices, and the assessment of cytotoxicity is a necessary step in the evaluation of their biocompatibility. Extracts of six addition-type and six condensation-type silicones have been tested with L929 cells according to the ISO 10993-Part 5 standard. The cytotoxicity was evaluated by three different methods: neutral red uptake, propidium iodide (PI) staining, and amido black staining. According to the selected specific assay, contact between cells and material extracts was maintained for 24 h in the first series of experiments; then, considering that in vivo application of these materials is restricted to a few minutes, additional experiments were performed after 1 h of cell/extract contact. Analysis of the results showed that the addition-type silicones are nontoxic even when tested after prolonged exposure of the cells to the materials while the condensation-type silicones were cytotoxic at 24 h of incubation. Nevertheless, harm to the patient actually could be negligible, considering its very short time of exposure in vivo. This is supported by our finding that most are not toxic after 1 h. We suggest that the experimental conditions of cytotoxicity testing have to be relevant to the in vivo situation; accordingly, the time of exposure should be designed carefully.

Amido Black↗
PubMed1996

Neuropeptide-stimulated cyclic guanosine monophosphate immunoreactivity in the neurosecretory terminals of a neurohemal organ.

The neuropeptide eclosion hormone acts on the nervous system of the tobacco hornworm, Manduca sexta, to increase cyclic guanosine monophosphate (cGMP) levels. In this study I describe the localization of some of the sites where these increases occur. Prior to pupal ecdysis, eclosion hormone stimulates an increase in cGMP in a network of fibers in the transverse nerve of each abdominal ganglion. Double-label experiments with propidium iodide suggest that the cGMP immunoreactivity is primarily localized in neurosecretory nerve endings. The time course of the increase in cGMP immunoreactivity and its requirement for lipid metabolism is similar to that of the cGMP increase measured by radioimmunoassay. The cGMP response in the transverse nerve is stage-specific, occurring prior to pupal ecdysis and not prior to larval or adult ecdysis.

Animals↗
PubMed2000

Spermatogenesis in the golden hamster during the first spermatogenic wave: a flow cytometric analysis.

In the present study propidium iodide was used as a fluorescent dye to stain DNA of cells of hamster testicular origin and fluorescent intensities were analyzed by flow cytometry. We used hamster testicular cells from the first spermatogenic wave to observe the consecutive appearance of the different types of cells during puberty. At 12 days postpartum (dpp) diploid cells (including spermatogonia) predominated and some tetraploid cells were also present. Tetraploid spermatocytes increased dramatically by 21 dpp. The first haploid cells appeared at 21 dpp but substantial numbers were first present at 23 dpp. Immature haploid cells predominated at 32 dpp. Elongating condensing spermatids appeared at 34 dpp and spermatozoa began to leave the testis to enter the epididymidis at 36-38 dpp marking the end of the first round of spermatogenesis. Using acridine orange staining flow cytometry, chromatin condensation was followed by measuring fluorescence decrease from early round spermatids to spermatozoa obtained from the initial segment and from the cauda epididymides. The major portion of sperm chromatin condensation (88-90%) in the hamster occurred in the testis and only 10-12% occurred during epididymal sperm maturation. Spermatozoa in the initial segment of the epididymidis of the hamster contained a small amount of RNA that was no longer present in sperm of the cauda epididymidis, indicating that RNA was lost during epididymal sperm maturation in this species. Mol. Reprod. Dev. 55:205-211, 2000.

Acridine Orange↗
PubMed1986

High-degree abnormalities of nuclear DNA distribution in SIg negative acute lymphoblastic leukemia with vacuolated blasts.

Among 65 consecutive patients with untreated adult acute lymphoblastic leukemia (ALL), six had peculiar clinical and cytologic features. Bone marrow and circulating blasts were large and showed prominent vacuolization, with variable degree of granular periodic acid-Schiff positivity in the cytoplasm. All patients had marked spleen and liver enlargement with cholestasis and without either lymph node or central nervous system disease. They achieved complete response to chemotherapy, and their median survival was longer than 12 months. Blast cells were studied for immunologic markers, propidium iodide flow cytofluorometric DNA content, and in vitro tritiated thymidine labeling index (3H-TdR LI). These showed a "null" phenotype in two cases, contained intracytoplasmic immunoglobulins (Cy mu) in two and were positive for CALL and Ia antigens in two others (one of which also contained Cy mu). Surface immunoglobulins (SIg) were found on less than 12% of cells, and T-cell markers were absent. In five cases, one or two stem lines with highly abnormal modal DNA content were found to coexist with diploid blasts. The 3H-TdR LI was high (8.5%-15.5%). Abnormal cell lines, after being cleared by chemotherapy, were found again at relapse. Additional cell lines appeared during the course of the disease in one patient, having different sensitivity to cytostatics. These cases of ALL apparently derive from B-cells not yet expressing SIg and have an exceptionally high incidence of aneuploid cell lines.

Adolescent↗
PubMed2001

Soluble MHC class I molecules induce cellular death in a CD8+ T-cell hybridoma tumor model.

T cells undergo activation-induced cell death (AICD) after T-cell receptor cross-linking in the absence of co-stimulation. In this study, we examined whether AICD induced by purified MHC class I molecules could be used to selectively eliminate tumor cells in T-cell malignancies. As a model, soluble H-2K(b) molecules refolded with the chicken ovalbumin SIINFEKL peptide (K(b)-OVA) and a CD8+ T-cell hybridoma (CD8-OVA) specific for this peptide were used. Addition of CD8-OVA hybridoma cells to plastic plates adsorbed with K(b)-OVA molecules resulted in a concentration-dependent decrease in cellular proliferation. Exogenous IL-4 further depressed the proliferation of CD8-OVA cells in a dose-dependent manner in the presence, but not in the absence, of K(b)-OVA. Staining of these cells with propidium iodide confirmed that the decrease in cellular proliferation was due to apoptosis. The cytotoxic effect of plastic-immobilized K(b)-OVA could be mimicked by soluble K(b)-OVA tetramers. Furthermore, co-injection of K(b)-OVA tetramers and CD8-OVA cells into mice suppressed the tumorigenicity of CD8-OVA cells. In conclusion, we describe a system whereby soluble MHC class I molecules can be used to selectively induce cellular death in a monoclonal T-cell tumor model. With future development, the use of MHC molecules may help to eliminate specific T cells in cases of T-cell malignancy and auto-immunity.

Animals↗