Direct fluorescent labeling of cells with fluorescein or rhodamine isothiocyanate. II. Potential application to studies of lymphocyte migration and maturation

The effect of direct cell labeling with fluorescein or tetramethyl rhodamine isothiocyanate on lymphocyte migration is examined. In vitro conditions of labeling are defined which (1) do not significantly affect immediate or long term viability of lymphocytes (up to 2 weeks after transfer in vivo), (2) do not alter normal lymphocyte migration, (3) do not affect expression or detectability of surface antigens, and (4) permit direct visualization and counter-staining with fluorescent antibody reagents for days after intravenous injection. The potential application of this method to studies of lymphocyte migration and maturation is discussed.

Direct fluorescent labeling of cells with fluorescein or rhodamine isothiocyanate. I. Technical aspects

A rapid and simple method of cell labeling by stable conjugation with fluorescein or rhodamine is described. Viable cells are incubated under benign conditions (near physiologic pH in normal media) with free fluorescein or tetramethyl rhodamine isothiocyanate, and are adequately separated from unreacted fluorochrome by washing or centrifugation through fetal calf serum. The effects of the pH, the time and temperature of incubation, and the concentration of cells, fluorochrome, and free protein in the media are described. The method labels all cell types, although to different degrees. Fluorescence microscopy reveals fluorescence throughout the cell, although chromatin appears relatively spared. Cellular fluorescence is fairly stable at 4 and 25 degrees C, decays rapidly at 37 degrees C, but is nonetheless visible for days even at this temperature. In the case of lymphocytes, intense fluorescence is obtained without affecting cell viability, and without alteration of the ability to mount a graft versus host response.

Cell lineage analysis by intracellular injection of fluorescent tracers

Cell lineages during development of the leech are revealed by injection of a fluorescent peptide, rhodamine-D-peptide, into identified embryonic cells. Use of this peptide together with a nuclear stain showed a stereotypic cleavage pattern of stem cells and their progeny. Combined injection of rhodamine-D-peptide and pronase demonstrated the arrest of stem cell production in the pronase-injected teloblast.

Rhodamin B stain for keratin: evaluation of its specificity and its application in dermal pathology

We used Rhodamin B stain in sections of normal skin, benign and malignant epithelial tumors and dermatoses. Keratin staining was uneven and showed variation in different lesions. While trichohyalin of the anagen hair follicle stained with intensity, keratohyalin granules failed to show similar reaction.

T cell maturation: thymocyte and thymus migrant subpopulations defined with monoclonal antibodies to MHC region antigens

The maturation sequences of thymocytes is known to some extent: A generative layer of subcapsular large lymphoblasts gives rise to a major population of small cortical thymocytes and a minor population of midsize medullary thymocytes. The relative contribution of these three populations to the peripheral T cell populations is not yet known. In this study, subcapsular lymphoblasts, cortical small cells, medullary cells, and thymic emigrant cells have all been analyzed by immunofluorescence for expression of the antigens H-2D, I-A, H-2K, and TL. H-2D is expressed brightly on all subcapsular large cells, dimly on cortical small cells, and brightly on all migrants, cortisone-resistant thymocytes (CRT), and peripheral T cells. I-A can be detected at low levels on 30 to 50% of cells in all the thymic subpopulations, and on 30 to 50% of migrants and peripheral T cells. Fifty to 80% of small cortical cells do not express detectable H-2K, but all the other subpopulations, both inside and outside the thymus, stain uniformly quite brightly. TL3 is expressed on 70 to 80% of subcapsular and cortical thymocytes, 30 to 40% of CRT, is undetectable on migrants but can be seen at low levels on 10 to 20% of spleen and lymph node T cells. The possibility that some or all of these antigens represent stable markers of separate lineages rather than unstable, stage-specific markers is discussed.

Receptor-mediated uptake of 3,3',5-triiodo-L-thyronine by cultured fibroblasts

Using video intensification fluorescence microscopy and tetramethylrhodamine (Rho)-labeled 3,3',5-triiodo-L-thyronine (T3), we studied the uptake of T3 by cultured mouse fibroblasts. After incubation of cells with Rho-T3 for 30 min at 37 degrees C the fluorescent hormone was concentrated in many small bright accumulations. With a 1000-fold excess of unlabeled T3, only weak background fluorescence was seen. Furthermore, when cells were incubated with Rho or Rho-thyronine only background fluorescence was detected. These results indicate that the cellular uptake of Rho-T3 occurred through a T3-specific receptor-mediated process. Most of these accumulations underwent saltatory motion in living cells, indicating that the T3 was contained within endocytic vesicles. When cultured cells were incubated with Rho-T3 for 60 min at 4 degrees C, only diffuse fluorescence was observed, Rho-T3 became concentrated in vesicles upon warming of the cells to either 23 degrees C or 37 degrees C. Simultaneous incubation of cells with fluorescein-labeled alpha 2-macroglobulin and Rho-T3 showed that Rho-T3 was internalized in the same vesicles as alpha 2-macroglobulin. Furthermore, as previously reported for alpha 2-macroglobulin in the presence of methylamine, dansylcadaverine, or bacitracin, clustering and internalization were inhibited but the overall fluorescence intensity of the cells did not appear to be affected. Because it has been previously shown that receptor-mediated endocytosis of alpha 2-macroglobulin occurs through clustering of ligands in coated pits on the cell surface, these results indicate that Rho-T3 follows the same pathway. Thus it has now been demonstrated that a low-molecular weight hormone enters cells by this pathway.

Effect of bleaching light on measurements of lateral diffusion in cell membranes by the fluorescence photobleaching recovery method

The Fc receptors for IgE on rat basophil leukemia 2H3 cells were labeled with either rhodamine- or fluorescein-conjugated IgE and then with Fab fragments of anti-IgE conjugated with the other dye. Fluorescence photobleaching recovery measurements of lateral diffusion were performed with one of the dyes before and after extensive bleaching of the other dye over an entire cell. Bleaching one dye did not affect subsequent measurements made with the other dye. We thus detect no evidence for photoinduced artifacts in fluorescence photobleaching recovery experiments.

Monitoring of phospholipid vesicle fusion by fluorescence energy transfer between membrane-bound dye labels

A sensitive method which utilizes fluorescence energy transfer to assay Ca2+ -or Mg2+ -mediated fusion of phospholipid vesicles is reported. More than 85% quenching results when phosphatidylserine vesicles labelled with dansyl phosphatidylethanolamine (donor) are fused with vesicles labelled with rhodamine phosphatidylethanolamine (acceptor) in the presence of 5 mM CaCl2 or 10 mM MgCl2. Higher concentrations of divalent cations are required to obtain maximal quenching when phosphatidylserine is partially replaced with phosphatidylethanolamine or phosphatidylcholine. The rate of vesicle fusion is dependent upon the concentrations of both cation and vesicles. Maximum quenching occurs within 5 min using phosphatidylserine vesicles and 5 mM Ca2+, but quenching is incomplete even after 20 h with 0.8--2 mM Ca2+. This probably reflects the heterogeneous size distribution of these vesicles, since the extent of fusion was found to correlated with vesicle size. Binding of antibody to membrane-localized phenobarbital hapten effectively blocks Ca2+ -mediated vesicle fusion. This effect can be inhibited by preincubation of the antibody with phenobarbital. Leakage of tempocholine from intact vesicles induced by 5 mM Ca2+ occurs even when fusion is prevented by bound antibody. This demonstrates that fusion is not a necessary requirement for Ca2+ -induced leakage.

Localization of mitochondria in living cells with rhodamine 123

The laser dye rhodamine 123 is shown to be a specific probe for the localization of mitochondria in living cells. By virtue of its selectivity for mitochondria and its fluorescent properties, the detectability of mitochondria stained with rhodamine 123 is significantly improved over that provided by conventional light microscopic techniques. With the use of rhodamine 123, it is possible to detect alterations in mitochondrial distribution following transformation by Rous sarcoma virus and changes in the shape and organization of mitochondria induced by colchicine treatment.

Vascular permeability associated with axonal regeneration in the optic system of the goldfish

An association between axonal regeneration and failure of the blood-brain barrier to plasma proteins has been studied in the goldfish. Vascular permeability was examined by fluorescence microscopy following injection of rhodamine B-labelled bovine serum albumin. Axonal regeneration was studied in adjacent silver-stained sections. Following transection of axons by crushing one optic nerve, it was found that a zone of increased vascular permeability accompanied the advancing front of regenerating axons through the optic nerve, chiasma and tract and into the stratum opticum of the tectum. These observations lend support to a hypothesis in which it is postulated that axons are able to regenerate only when plasma proteins are available to their growth-cones. However, it is also possible that the increased permeability is a consequence rather than a cause of the presence of regenerated axons.

Laser detection of latent fingerprints: preparation of fluorescent dusting powders and the feasibility of a portable system

A simple procedure for the preparation of dusting powders with a variety of fluorescent colors is described. Such powders permit detection of latent prints by laser even when the surfaces holding the latent prints luminesce strongly. A possible portable laser detection system is also suggested.

Experimental depression of junctional membrane permeability in mammalian cell culture. A study with tracer molecules in the 300 to 800 Dalton range

Cell-to-cell junctional permeability in mammalian cell cultures was probed with a series of fluorescent tracers ranging 300 to 800 in molecular weight, during treatment with metabolic inhibitors, Ca-transporting ionophore, and carbon dioxide. Treatment with the combination of cyanide and iodoacetic acid (1--2 mM each), but not with either one alone, caused reversible junctional blockade to all tracer molecular species, large and small. (Electrical coupling, however, persisted in a proportion of the junctions tested.) Treatment with the ionophore A23187 (2--10 micrometers) or with CO2 (an atmosphere of 100% CO2 equilibrated with the medium) produced selective junctional blockade: transmission of a 688 and an 817-dalton tracer was generally blocked, while that of a 376-dalton traced and, in certain conditions, that of a 559-dalton one, persisted. The junctional effect of the ionophore required the presence of Ca in the external medium; and effective junctional blockade by CO2 required pretreatment in medium with high Ca concentration or, interchangeably, pretreatment in medium with high CO2 concentration. In one cell type, prolonged exposure to medium with high Ca concentration alone sufficed to block transmission of the 688-dalton tracer. These effects are discussed in terms of the Ca hypothesis of junctional permeability regulation. In comparison with mammalian (or other vertebrate and invertebrate) organized tissues or with insect cell cultures, the mammalian cell cultures are more resistant to junctional blockade. This difference in transmission stability is discussed in terms of the electron-microscopic finding in the mammalian cultures of fine, bilateral cell processes connected by gap junctions.

Viability assessment by dye exclusion. A fluorescent method for fungal cells

A new fluorescent staining technique for fungi utilizes the differential affinity of dead cells for rhodamine B. A mounting medium has been devised that includes the dye. This medium allows direct processing of cells from a broth and provides optimal conditions for fluorescence intensity. Comparison with the standard methylene blue exclusion test as applied to the Candida albicans yeast phase indicates similar specificity. Various pseudohyphae and several fungi also exhibited selective uptake of the dye when killed. This technique should prove useful in studying the effect of both drugs and cells on pathogenic yeasts.

Serological differentiation between infected and vaccinated cattle by visual and quantitative immunofluorescence using Brucella abortus antigen coupled sepharose beads

The ability to differentiate cattle infected with brucellosis from animals vaccinated against the disease is of considerable economic advantage in countries adopting eradication schemes. Current serological tests such as bacterial tube agglutination do not readily distinguish cattle in this way. An immunofluorescent procedure was investigated in an attempt to overcome this problem. Antigenic extract of brucella abortus strain 544/W were coupled to sodium metaperiodate oxidised Sepharose CL4B beads. Following coupling, the beads were chemically reduced or blocked with rhodamine labelled BSA prior to reduction. Characterised bovine serum samples were tested by indirect immunofluorescence on both types of bead and by standard bacterial tube agglutination. Serological discrimination between infected and vaccinated cattle was achieved by fluorescence quantitation using unblocked beads and by visual determination of colour using rhodamine-albumin blocked beads. Bacterial tube agglutination failed to distinguish between the two groups of sera.

Cerebral cortical microfluorometry at isosbestic wavelengths for correction of vascular artifact

Microfluorometric measurements of cerebral cortical mitochondrial respiration in vivo are obscured by hemodynamic and oximetric artifacts. Isosbestic fluorometry provides appropriate correction for these vascular phenomena and permits simultaneous evaluation of mitochondrial nicotinamide adenine dinucleotide redox state, microcirculatory volume, and hemoglobin oxygenation.

Copper stains and the syndrome of primary biliary cirrhosis. Evaluation of staining methods and their usefulness for diagnosis and trials of penicillamine treatment

Use of Shikata's stain was found to be a sensitive method for the demonstration of copper-protein complexes, but use of the rhodamine stain may be more reliable. Interobserver agreement was slightly better with Shikata's stain. Hepatic copper increased with the histologic progression of chronic nonsuppurative destructive cholangitis (CNDC). All specimens that contained Mallory bodies and most specimens (91%) that contained bile yielded positive copper stains. No correlation was found between positive copper stains and other histologic features. A strongly positive copper stain aided in the diagnosis of CNDC. All specimens with negative copper stains contained less than 250 microgram of copper per gram of dry weight. From a strongly positive copper stain, the chemical copper content could not be predicted with certainty. Shikata's method seemed adequate to evaluate penicillamine treatment trials.

Double-staining procedure for the fluorescent treponemal antibody absorption (FTA-ABS) test

The fluorescent treponemal antibody absorption (FTA-ABS) double-staining procedure was reproducible, comparable to the conventional test, and easy to read. We recommend the use of the FTA-ABS double-staining procedure for microscopes with incident illumination, the 100 x/1.30 oil achromatic objective and the 6.3 x ocular to obtain optimal fluorescence, and the KP560 as a barrier filter to exclude rhodamine emission when fluorescein fluorescence is read. With this system, errors related to poor focusing or failure to visualise treponemes on all smears should be eliminated.

Re-evaluation of sputum staining for the diagnosis of pulmonary tuberculosis

Data were collected at 2 teaching institutions, University Hospital, University of Michigan (UMH) and University of California at Los Angeles (UCLA) Hospital, to evaluate the usefulness of the auramine-rhodamine fluorochrome stain in the diagnosis of pulmonary tuberculosis in hospitalized patients. The patients studied had received no prior therapy, and their sputum specimens were positive for a pathogenic Mycobacterium by microscopy or culture or both. The true-positive smear rate was 0.88 at UMH and 0.83 at UCLA; the relative false-positive smear rate was 0.12 at UMH and 0.17 at UCLA. The sensitivities at UMH and UCLA were 0.78 and 0.51, respectively, and the specificity was greater than 0.99 at both. The data suggest that sputum stained by the fluorochrome method is useful and reliable for the diagnosis of pulmonary tuberculosis, because the false-positive rates are acceptably low in hospitalized patients.