A high-frequency RFLP at the human TFE3 locus on the X chromosome

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Gelatin sponge model of effector recruitment: tumoricidal activity of adherent and non-adherent lymphokine-activated killer cells after culture in interleukin-2

This study examined the specific tumoricidal activity of lymphokine-activated killer (LAK) cells derived from tumor-infiltrating lymphocytes that prevent the growth of secondary tumors in animals harboring progressing primary tumors. A pre-implanted gelatin sponge was employed to capture infiltrating host effectors during the expression of concomitant tumor immunity. Additionally, this study compared the cytolytic activity of these sponge-derived cells with those of counterpart splenic lymphocytes. The cells from both sources were cultured for 4 days in IL-2 to generate LAK cells which were further expanded in IL-2-containing medium for up to 11 days. The cytotoxic activities of these cells were measured in a Chromium-51 release assay. The data revealed that the culture of splenic, or sponge-derived lymphocytes results in the emergence of non-adherent and adherent cell populations with LAK activity. The 4-day sponge-derived LAK cells (adherent and non-adherent) exhibited significant cytolysis of EMT6 cells while the spleen-derived counterparts showed minimal cytotoxicity toward these targets. Some NK activity in LAK cells derived from both sources was evident by their lysis of YAC-1 cells. LAK cells from both sources were incapable of lysing histo-compatible EL-4 (H-2b) tumor cells. The lysis of the EMT6 cells by the sponge-derived LAK cells was maintained over an 11-day period of culture in IL-2. Conversely, the spleen-derived LAK cells were unable to significantly lyse EMT6 cells during this period of in vitro culture. These results show the superior specific tumoricidal activity of LAK cells derived from lymphocytes mediating tumor rejection in vivo (sponge-derived) over that of counterpart splenic lymphocytes.

Sorting minor subpopulations of cells: use of fluorescence as the triggering signal

Flow cytometric cell sorting is commonly used to obtain purified subpopulations of cells for use in in vitro and in vivo assays. This can be time-consuming if the subpopulations of interest represent very low percentages of the cell suspension under study. Often the desired subpopulations are identified by two-color immunofluorescence staining. Generally, cell sorting is performed with a flow cytometer configured to trigger on light scatter signals, then sort windows are set based upon the signals from both fluorescent markers. We demonstrate that triggering the cytometer with the fluorescence signal from antibody staining common to both of the desired subpopulations, then sorting the subpopulations based upon staining of a second marker, substantially increases the speed of cell sorting vis-à-vis traditional methods. This is because undesired events are not analysed, allowing an increase in the throughput rate. While desired subpopulations of cells can be obtained by this method, undesired (i.e., nonstaining) cell "contaminants" increase and may require a second sort. The combined time for the initial enrichment sort and a second sort can be less than sorting once using standard methodology. Alternatively, the degree of contamination may be controlled by adjusting the concentration of the cell suspension and by the sample flow rate.

Use of a photolabeling technique to identify nonviable cells in fixed homologous or heterologous cell populations

Flow cytometric determination of viable versus nonviable cells in fixed samples can be accomplished by utilizing the irreversible binding of photoactivated ethidium monoazide (EMA). EMA is a positively charged molecule which is excluded by cells with intact membranes (viable cells), included by cells with damaged membranes, and can be photochemically crosslinked to nucleic acids using visible light. EMA fluorescence can be excited using a standard argon laser operating at 488 nm and is able to be distinguished from fluorescein and phycoerythrin. Fixation is important when analyzing cells from a potentially infectious origin. EMA is photochemically crosslinked and therefore unable to leak out of cells when removed from the extracellular media, unlike propidium iodide (PI) or other viability stains, which were heretofore commonly used. We demonstrate the usefulness of EMA in combination with fluoresceinated and phycoerythrin labeled monoclonal antibodies in immunophenotyping. The photoaffinity labeling technique allows for a quick and efficient means of identifying nonviable cells which cannot be distinguished on the basis of light-scattering properties.

13-cis retinoic acid augments the production of macrophages in mouse bone marrow cultures stimulated with interleukin 3

Mouse bone marrow cells in liquid culture with interleukin 3 generate nonadherent granulocytes, mast cells, and macrophages. The addition of 13-cis retinoic acid (13cRA) (10(-8)-10(-6) M) enhanced proliferation of the nonadherent cells, and concentrations greater than 5 x 10(-7) M stimulated a sixfold increase in adherent macrophages. Four-color flow cytometry was used to identify the lineages present using the following antibodies: MAC1 (granulocytes and macrophages), F4/80 (macrophages), B54.2 (mast cells), and H12 (anti-Thy1.2 to identify myeloid precursors). This analysis demonstrated a twofold increase in MAC1+ F4/80+ cells, which were sorted and identified morphologically as macrophages. 13cRA also increased by 60%-95% the numbers of colony-forming cells responsive to interleukin 3 (IL-3) and macrophage colony-stimulating factor (M-CSF) but did not significantly change the colony-forming cells responsive to granulocyte-macrophage colony-stimulating factor (GM-CSF). These data suggest that 13cRA increases the production of macrophages by modulating the commitment of IL-3-expanded progenitor cells to the macrophage lineage.

Quantitation of the host cell infiltration kinetics of the nonimmunogenic colon 26 tumor by multiparameter flow cytometry

In this study, we examined the kinetics of host cell infiltration into the nonimmunogenic Colon 26 tumor. We found that 1 x 10(4) cells were required to produce tumors in 100% of mice. The vivo doubling time was 42.5 h, and a barely palpable tumor contained 8 x 10(6) cells. No evidence of concomitant immunity was found. The number of host cells infiltrating the in vivo tumors increased at the same rate as the number of tumor cells, but averaged only 22% of total cells. Cycling T lymphocytes were present in the host cell infiltrate of this tumor. In addition, approximately 50% of in vivo Colon 26 cells were Thy-1.2 positive. The observed characteristic of low immunogenicity makes it a useful murine model for studying human malignant tumors.

Regulation of MHC class II gene expression in macrophages by hematopoietic colony-stimulating factors (CSF). Induction by granulocyte/macrophage CSF and inhibition by CSF-1

CSF-1 and granulocyte/monocyte CSF (GM-CSF) were shown to modulate the levels of Ia gene and protein expression in bone marrow-derived macrophages (BMM). Recombinant GM-CSF induced high levels of Ia expression, similar to the levels induced by INF-gamma, while IL-3 had no effect. In contrast, recombinant CSF-1 not only suppressed the basal levels of Ia gene and protein expression in BMM, but also inhibited the induction of Ia by IFN-gamma and GM-CSF. Basal levels of Ia were not inhibited by recombinant CSF-1 until after 16-24 h of culture, suggesting an indirect mechanism of suppression. IFN-alpha/beta and PGE2 were shown not to be involved in the CSF-1 inhibition of basal levels of Ia expression. However, the CSF-1-mediated suppression of both the basal levels of Ia expression and the induction of Ia in BMM by IFN-gamma and GM-CSF did correlate with the induction of cellular proliferation. These data imply that in addition to regulating hematopoiesis, CSFs may regulate the initiation of the immune response through their effects on Ia expression in macrophages.

High-speed DNA sequencing: an approach based upon fluorescence detection of single molecules

We are developing a laser based technique for the rapid sequencing of large fragments (approximately 40 kb) of DNA based upon the detection of single, fluorescently tagged nucleotides cleaved from a single DNA fragment. We have demonstrated significant progress on several of the important steps of this technique. The projected rate of sequencing is several hundred bases per second which is orders of magnitude faster than existing methods. Once developed, this technology could be utilized by investigators for rapid sequencing of genetic material from virtually any source.

Resolving leukocytes using axial light loss

Axial light loss (ALL) is the measurement of the total light lost from the laser beam at 0 degrees when a particle passes through the beam. Used in combination with the monoclonal antibody CD45, ALL can effectively resolve lymphocytes, monocytes, granulocytes, and dead cells in viable or fixed preparations of human peripheral blood. A bivariate display of ALL vs. CD45 clearly resolves all granulocytes from lymphocytes; although degranulated granulocytes cannot be resolved with forward-angle and right-angle light scatter, they are clearly resolved in right-angle scatter vs. CD45. A blood differential can be performed, with a single laser flow cytometer and three colors of fluorescence, when ALL is combined with fluoresceinated CD45 to resolve leukocytes, phycoerythrin-labeled NKH1 to resolve natural killer cells, and biotinylated CD3 in combination with DuoCHROME, the phycoerythrin/Texas red conjugate fluorochrome from Becton Dickinson, to resolve T-cells. B-cells are the only cells negative for both phycoerythrin and Texas red. When PE CD4 is included, the CD3+ CD4+ T-cell subset is resolved from the CD3+ CD4- subset comprising mainly the CD3+ CD8+ T-cell subset. The addition of propidium iodide is unnecessary since ALL clearly resolves dead cells in a viable preparation of human peripheral blood. Furthermore, since ALL resolves these cells even after fixation in paraformaldehyde, all samples can be fixed prior to analysis, thereby minimizing the potential biohazard risk.

Flow cytometric analysis of oncogene expression in human neoplasias

More than 40 oncogenes have been described and characterized. These oncogenes code for products intimately associated with cell proliferation. Their products include growth factors, growth factor receptors, transmembrane signaling molecules, second and third messengers, and nuclear proteins involved in gene regulation. Some oncogenes seem to be expressed in every malignancy, while others seem to be expressed only in certain malignancies. This expression pattern suggests some oncogenes may have tissue type specificity. Some oncogenes may also be expressed in only a fraction of the malignant cells, such as the proliferating cells. Flow cytometry has only recently been applied to the simultaneous measurement of oncoprotein levels and DNA content of malignant cells. As this application is developed, our understanding of oncogene expression in malignancy will be enhanced and its diagnostic importance will be realized.

General principles of multiparameter flow cytometric analysis: applications of flow cytometry in the diagnostic pathology laboratory

Recent developments in the design of flow cytometric instrumentation and advances in computerized methods of data analysis have produced flow cytometers that are compatible with the clinical laboratory setting. Because flow cytometry is impacting on virtually every area of diagnostic pathology (particularly the subspecialties of hematology, immunology, infectious disease, transplantation monitoring, neoplasia, and genetics), it is essential that pathologists develop a general understanding of flow cytometric techniques. In addition to new developments in instrumentation, simplification of laser design and advances in fluorochrome chemistry have provided several new sophisticated tools to make multiple correlative biological measurements on normal and neoplastic cells in the clinical setting. Flow cytometric analysis thus allows the pathologist to more effectively diagnose, predict prognosis, and monitor disease progression. This report reviews the basic components of flow cytometric instrumentation, the physical and biological parameters that may be assessed using flow cytometric techniques, and the multiparametric data analysis systems available for the clinical laboratory.

Flow cytometric analysis of I-J expression on murine bone marrow-derived macrophages

Attempts to analyze bone marrow-derived macrophages (BMDM) by flow cytometry have been prohibited because of their high autofluorescence. Using an autofluorescence reduction method of Steinkamp and Stewart to reduce the autofluorescence of BMDM, we were able to examine several macrophage populations for their expression of I-A, I-J, and Mac-1 cell surface determinants. Bone marrow cells examined immediately after removal from the femur contain 50-60% Mac 1-positive cells (mainly granulocytes). During the next few days granulocytes and nonmacrophage precursor cells die, and the number of Mac 1-positive cells decrease. Once the bone marrow cells have been maintained in L cell conditioned medium (LCM) for 2 to 3 days, the number of cells expressing Mac 1 increases rapidly from 20% to 98% during the next 3 to 4 days. Bone marrow cells grown in LCM do not express I-J until these cells have been in culture 3 to 4 days, and the number of cells expressing I-J (up to 90% positive) parallels the increase in macrophages. Bone marrow cells maintained in LCM did not express detectable I-A during the 14 days these cells were examined. Two other macrophage populations often used in a variety of immunological studies were analyzed by flow cytometry. We found that the majority (up to 80%) of peritoneal cells expressed I-A, and only 20% of peritoneal cells had I-J cell surface determinants. On the other hand, peritoneal exudate cells collected 4 days after thioglycolate medium treatment were predominantly I-J positive (up to 70%), and only about 30% of these cells expressed I-A cell surface antigens. The binding of anti-I-J IgM antibody to BMDM was not to Fc receptors because pretreating these cells with up to 25 micrograms of an IgG2a myeloma protein did not block anti-I-J antibody binding. The addition of 25-200 micrograms of monoclonal anti-Fc receptor antibody was also ineffective in blocking the binding of a monoclonal anti-I-Jk antibody to BMDM. Pretreatment of BMDM with the IgM fraction of several control IgM antibody preparations did not block the specific binding of fluoresceinated anti-I-J IgM antibody. BMDM provide a pure population of macrophages that express a significant level of cell surface I-J antigens. Bone marrow cells grown in LCM are essentially devoid of other contaminating cells, and the increase in the number of I-J-positive cells parallels the increase in macrophages in these cultures.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of granulocytes and mast cells in cultures of mouse bone marrow stimulated with interleukin-3

Bone marrow cells in liquid culture with interleukin 3 produce a population of non-adherent granulocytes and mast cells. Flow cytometry was used to identify granulocytes and mast cells on the basis of the physical properties of perpendicular light scatter (PLS) and coulter volume (CV) as well as the expression IgE and CR3 receptors. Multicolor analysis indicated there were subpopulations of Thy1.2 positive cells which transiently appeared in these cultures and also expressed IgE receptors, CR3 receptors or neither of these receptors. The data suggested a differentiation scheme in which Thy1.2 positive precursor cells give rise to granulocytes and mast cells. Further evidence for this differentiation scheme was provided from CV vs. PLS distributions which showed increases in CV and PLS as Thy1.2 positive cells differentiated into mast cells and decreases in CV and PLS as Thy1.2 positive cells differentiated into granulocytes.

Isolation and reactivity of host effectors associated with the manifestation of concomitant tumor immunity

In this study, we have measured the specific tumoricidal activity of tumor-infiltrating lymphocytes that prevent the growth of secondary tumors in animals harboring progressing primary tumors (concomitant immunity). Since no tumor grows at the challenge site when concomitant immunity is established, tumor cells were inoculated into a preimplanted gelatin sponge whose subsequent solubilization in collagenase permitted the retrieval of leukocytes after tumor challenge. Primary progressing EMT6 tumors were established in normal BALB/c mice and 10 days later they were challenged with a secondary tumor inoculum introduced through a preimplanted gelatin sponge. At 3, 7, and 10 days after the administration of the tumor inoculum challenge, a monodispersed suspension of infiltrating leukocytes was recovered by collagenase digestion of the sponge matrix and tested for cytotoxicity toward EMT6 tumor targets. Cytotoxic T-lymphocytes with tumoricidal activity accumulated at the site of the secondary tumor challenge by 3 days. This antitumor activity was maximal 7 days following challenge and decayed thereafter. Splenic lymphocytes from these animals showed little cytotoxicity. In animals harboring a primary tumor, lymphocytes found in sponges that were not inoculated with tumor cells were not cytotoxic. We interpret these data to indicate that cytotoxic lymphocytes migrate to, and accumulate at the site of the tumor but not at other sites and that peripheral sources of lymphocytes in tumor-bearing animals such as the spleen may not be the best source of effector cells for evaluating the host's immune response to its tumor. The approach described here may also be useful in studying the mechanisms for host control of metastatic disease.

The effect of low-dose irradiation on unstimulated and PHA-stimulated human lymphocyte subsets

A culture system was used to evaluate the radiosensitivity of CD4+ and CD8+ T cells, Leu 19+ cells, and B cells obtained from normal adult males. Unstimulated CD8+ lymphocytes (D0 = 55 cGy) were twice as radiosensitive as CD4+ cells (D0 = 115 cGy). B cells had an intermediate radiosensitivity (D0 = 100 cGy). Leu 19+ cells were much more radioresistant and expressed a D0 of 550 cGy. When lymphoid cells were irradiated 1 or 4 days before phytohemagglutinin (PHA) stimulation, they were more radiosensitive than if they were first stimulated with PHA and then irradiated. When lymphoid cells were irradiated 1 h after PHA stimulation each lymphocyte subset was characterized by an increase in the D0 to 150 cGy for B cells to 290 cGy for CD4+ cells, and to 240 cGy for CD8+ cells. In contrast, Leu 19+ cells exhibited a decrease in their D0 to 290 cGy after they were stimulated by PHA.

Automated single-cell manipulation and sorting by light trapping

Following the recently reported trapping of biological particles by finely focused laser beams, we report on the automated micromanipulation of cells and other microscopic particles by purely optical means as well as on a newly observed interaction between particles in the trapping beam. A simple instrument is described which allows single cells to be positioned with high accuracy, transported over several millimeters, and automatically sorted on the basis of their optical properties. These operations are performed inside a small enclosed chamber without mechanical contact or significant fluid flow. Potential applications of this technique in experimental cell biology are discussed.

A modular detector for flow cytometric multicolor fluorescence measurements

A modular detector for measuring multicolor fluorescence from cells illuminated by single or multiple lasers has been developed for flow cytometers. Motion picture projector, camera, and CCTV/video lenses were evaluated for use in the detector by comparing their physical characteristics, image quality, and light collection efficiencies. A 25-mm focal length F/0.95 CCTV lens was selected, based on our criteria and test results. The detector was constructed out of square aluminum extrusion channels. A CCTV lens mounted on the outside of the first channel collected light emitted from cells and collimated it towards filters and secondary CCTV lenses located in each channel. The secondary lenses functioned as relay optics for directing and focusing light onto pinhole spatial filters for measurement by photomultipliers. The detector design allowed any number of channels to be connected together and the versatility for making simultaneous or sequential measurements. Measurements on lymphocytes labeled with four monoclonal antibodies conjugated to fluorescent dyes and measurements on viable tumor cells stained for DNA content and with three fluorescent-labeled antibodies were used to demonstrate the detector's capabilities.

Differential expression and regulation of the c-src and c-fgr protooncogenes in myelomonocytic cells

To study the expression of src-related protooncogenes during the development of myeloid cells and the regulation of these genes by the colony-stimulating factors that control myelopoiesis, normal monocytic cells at distinct stages of differentiation were derived from murine bone marrow with the monocytic lineage colony-stimulating factor CSF-1. Protooncogene expression was also examined in uncultured human myeloid leukemia cells. While c-src transcripts were detected in myeloid leukemia cells representative of all stages of differentiation, the highly related gene c-fgr was expressed at high levels only at later developmental stages, both in normal cells committed to the monocytic lineage and in leukemic cells with a differentiated myelomonocytic phenotype. When bone marrow-derived monocytic cells were synchronized and stimulated to proliferate with CSF-1, c-fgr transcripts (but not transcripts from the highly related genes c-src or c-yes) were induced 8 hr after the addition of CSF-1 and decreased to low levels by 20 hr as the monocytic cells entered S phase. The selective induction of c-fgr mRNA by CSF-1 suggests that this tyrosine kinase may have a unique function in normal monocytic cells, distinct from other src-related tyrosine kinases.

Analysis of heavy metal immunotoxicity by multiparameter flow cytometry: correlation of flow cytometry and immune function data in B6CF1 mice

Bone marrow and spleen cells obtained from female B6C3F1 mice given a single i.p. exposure to cadmium acetate (0.9 mg/kg), lead acetate (12 mg/kg), or sodium acetate (12 mg/kg), were studied using flow cytometry, immunologic, and hematologic assays. Significant changes were detected in subpopulations of bone marrow cells using multiparameter flow cytometry within 1 day following treatment with cadmium or lead. Bone marrow cells obtained from B6C3F1 mice 5 days after treatment with cadmium or lead were found to have a decreased number of cells expressing Mac-1, 55-7.2, 14.8, and Lyt-1 antigens, suggesting a shift to immature cell types. An increase in the number of progenitor cells (CFU-C) obtained from the bone marrow of mice treated with heavy metals was also noted 5 days after exposure to cadmium or lead. A time-dependent suppression of the in vitro primary humoral immune response of spleen cells to SRBCs, TNP-Ficoll and TNP-LPS was produced by cadmium or lead treatment. Suppression of the mitogenic response of spleen cells to Con A, PHA, and LPS was also found to be time-dependent. Spleen cell surface marker expression (Mac-1, Lyt-1, Lyt-2 and 14.8) was altered in response to cadmium or lead treatments, but these changes did not appear to correlate with the humoral immunity or mitogen-induced proliferation data. These studies demonstrate that changes in cell surface markers on discrete subpopulations of lymphoid cells present in the spleens of heavy metal exposed mice may not correlate with alterations in the functional activity of these cells. However, changes in murine bone marrow surface markers in response to cadmium or lead treatment predicts a shift to immature cell types, which appeared to correlate with the increase in CFU-C activity.

Regulation of myelopoiesis

Myeloid cells are produced by the bone marrow from stem cells and progenitor cells. This review summarizes the current understanding of how this process is regulated. Regulation of progenitor cell proliferation and differentiation occurs in microenvironments present within the bone marrow as well as on the systemic level by the release of regulators into the circulation. The regulators of central importance to myelopoiesis are growth factors necessary for the proliferation and differentiation of progenitors. These growth factors have recently been characterized and studies indicate that there is a hierarchy of factors acting upon successive differentiation stages of progenitors. Endotoxin appears to be a major modulator of myeloid growth factor production. Other inhibitors of myelopoiesis are also discussed. Regulation of myelopoiesis therefore involves a balance between growth factor production and inhibition by other factors.

Comparison of five short-term assays that measure nonspecific cytotoxicity mediated to tumor cells by activated macrophages

Five different short term assays (less than 48 h) used to measure macrophage-mediated, nonspecific cytotoxicity were compared under similar conditions in the same laboratory using the same reagents. The purpose was to determine the extent to which results were comparable. Three of the assays were dependent on the release of a radioisotope to measure cytotoxicity, one was dependent on cell counting, and the last was dependent on flow cytometric quantification of remaining viable tumor target cells after they had been exposed to macrophages. The variables examined were the following: three different populations of macrophages; four different kinds of target cells; two types of radioisotopes; and two different agents that trigger the expression of cytolytic activity by primed macrophages. Recombinant gamma interferon was used as the priming agent in all the experiments. There was unexpectedly good agreement between the results of the various assays. No differences were found among the different macrophage populations, the isotopes or the triggering agents. Perhaps the most important finding was that differences in target cell susceptibility to killing by activated macrophages, which were apparent in assays of less than 24 h duration, disappeared when the same kinds of targets were compared in assays of greater than 40 h duration. The results of this study are an important first step toward standardizing the way in which macrophage-mediated, nonspecific cytotoxicity is measured in short-term assays, laboratory to laboratory.

Dual-laser, differential fluorescence correction method for reducing cellular background autofluorescence

A method has been developed for reducing the intrinsic autofluorescence background component in cells labeled with fluorescent antibodies, thus permitting low levels of antibody-binding on highly autofluorescent cells to be quantified. The method is based on the broad autofluorescent excitation spectra compared to the well-defined spectra of the fluorescent label. Two laser wavelengths were used, one optimally to excite the fluorescent label plus autofluorescence and the second to excite only the autofluorescence. Two fluorescence measurements were made in the same wavelength region and the signals were subtracted on a cell-by-cell basis using a difference amplifier to zero the autofluorescence and amplify the signal from the fluorescent label. Test results on unlabeled autofluorescent macrophages showed that the autofluorescence component was reduced by balancing the signal inputs to the difference amplifier. When labeled macrophages were analyzed, the autofluorescence was reduced and the fluorescent-labeled antibody-binding component was amplified. The method was also able to resolve labeled lymphocytes from unlabeled autofluorescent macrophages.

Flow cytometry Coulter volume analysis of lead- and cadmium-induced cellular alterations in bone marrow obtained from young adult and aged Balb/c mice

Flow cytometry Coulter volume analysis was used to examine the effects of an acute exposure to cadmium or lead on subpopulations of Balb/c bone marrow cells. A significant shift in the volume of Balb/c bone marrow cells was detected in response to a single i.p. injection of cadmium acetate (Cd) or lead acetate (Pb) compared to sodium acetate (Na)-treated mice. An increase in the relative number or size of myeloid/monocytic cells was noted in the bone marrow of cadmium or lead-treated mice. This effect was more pronounced in aged Balb/c mice than in young adults. These studies suggest the flow cytometry Coulter volume analysis may be a useful and sensitive technique for the assessment of cellular changes that occur in the bone marrow in response to xenobiotic exposure.