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PubMed2001

Use of formalin-fixed, propidium iodide-stained human leukocytes as a standard for enumerating CD4+ T lymphocytes in a single-platform assay.

A new, inexpensive method is described that enables lymphocytes to be enumerated very precisely. Normal leukocytes were simultaneously stained and fixed with a propidium iodide-paraformaldehyde solution. The preparation obtained (CellBeads) was used as an internal standard for cell enumeration by flow cytometry and was stable at 4 degrees C for at least 60 days. Unlike synthetic beads, the CellBeads behaved similarly to normal cells during red blood cell lysis and cell washing procedures. When known numbers of CellBeads were added to whole-blood samples and the numbers of CellBeads and lymphocytes were determined, highly reproducible and accurate enumerations were obtained-far more so than when synthetic beads were used. This inexpensive method is suitable for routine use.

CD3 Complex↗
PubMed2005

N-methyl-D-glucamine and propidium dyes utilize different permeation pathways at rat P2X(7) receptors.

Activation of membrane P2X(7) receptors by extracellular ATP [or its analog 2',3'-O-(4-benzoylbenzoyl)-ATP] results in the opening within several milliseconds of an integral ion channel that is permeable to small cations. If the ATP application is maintained for several seconds, two further sequelae occur: there is a gradual increase in permeability to the larger cation N-methyl-d-glucamine and the cationic propidium dye quinolinium, 4-[(3-methyl-2(3H)-benzoxazolylidene)methyl]-1-[3-(triethylammonio)propyl]diiodide (YO-PRO-1) enters the cell. The similarity in the time course of these two events has led to the widespread view that N-methyl-d-glucamine and YO-PRO-1 enter through a common permeation pathway, the "dilating" P2X(7) receptor pore. Here we provide two independent lines of evidence against this view. We studied single human embryonic kidney cells expressing rat P2X(7) receptors with patch-clamp recordings of membrane current and with fluorescence measurements of YO-PRO-1 uptake. First, we found that maintained application of the ATP analog did not cause any increase in N-methyl-d-glucamine permeability when the extracellular solution contained its normal sodium concentration, although YO-PRO-1 uptake was readily observed. Second, we deleted a cysteine-rich 18-amino acid segment in the intracellular juxtamembrane region of the P2X(7) receptor. This mutated receptor showed normal YO-PRO-1 uptake but had no permeability to N-methyl-d-glucamine. Together, the clear differential effects of extracellular sodium ions or of mutation of the receptor strongly suggest that N-methyl-d-glucamine and YO-PRO-1 do not enter the cell by the same permeation pathway.

Benzoxazoles↗
PubMed1981

Fundamental aspects of the interaction of propidium diiodide with nuclei acids studied in a model system of polyacrylamide films.

Qualitative and quantitative aspects of the fluorescent propidium diiodide (PI) staining method have been investigated with model films of polyacrylamide gel incorporated with DNA, RNA, and other macromolecular compounds. PI was found to bind specifically to DNA and RNA, most probably by intercalation into double-stranded regions. Proteins, glycogen, and glycosaminoglycans did not show fluorescence after PI staining. Optimal conditions for dye binding and differentiation have been defined. The stability of nucleic acid-PI complexes, as present in model films, was shown to be very high in distilled water, while dissociation rapidly occurred in ionic media. Linear relationships were found between the fluorescence intensity of bound PI and both the thickness of the model films and the amount of DNA or RNA incorporated. The presence of histone protein bound ionically to DNA did not influence the fluorescent PI binding ability in any appreciable amount.

Animals↗
PubMed1982

A stable propidium iodide staining procedure for flow cytometry.

A propidium iodide (PI) staining procedure is described in which 50 micrograms/ml PI in 10(-2) M Tris, pH 7.0, with 5 mM MgCl2 is used to stain murine erythroleukemia cells (MELC) grown in suspension culture as well as single cell suspensions derived from rat kidney adenocarcinoma and human prostatic carcinoma. Specificity of staining of nuclear DNA is achieved by enzymatic removal of RNA using RNAse in the staining solution. Virtually identical histograms, with the same G1 peak height and closely similar coefficients of variation (CVs), are obtained using a wide range of RNAse concentrations on replicate samples of MELC if the incubation times are sufficiently prolonged when employing the lower enzyme concentrations. For 1 mg/ml RNAse on logarithmically growing MELC, 30 min incubation at 37 degrees C is needed to obtain a maximum G1 peak height and optimal CV and there is no significant change in the histogram if the incubation is prolonged to 4 hr. For every 4-fold decrease in RNAse concentration, the incubation time at 37 degrees C must be doubled to obtain the same maximal G1 peak height and optimal CV. Unfixed cell preparations, whether derived from suspension or monolayer cultures or from solid tumors, are stable for 2 or more weeks if stored at 4 degrees C between flow cytometric analyses and histograms are usually only minimally altered if the stained cell samples are stored for 1-2 months at 4 degrees C. Sample decay is associated with bacterial contamination. If sterile preparative techniques are used initially, subsequent contamination of the stained preparations may be minimized by adding sodium azide to the stained samples at 0.1% without influencing fluorescence intensity. Glycerine may be added to 10% and the samples slowly frozen for storage without altering DNA histogram shapes. The simplicity of sample preparation and the stability of the resulting stained cell samples makes this procedure suitable for repetitive comparative sampling of tissue and cell populations over prolonged time spans.

Animals↗
PubMed1985

An improved method to determine cell viability by simultaneous staining with fluorescein diacetate-propidium iodide.

A rapid, simultaneous double-staining procedure using fluorescein diacetate (FDA) and propidium iodide (PI) is described for use in the determination of cell viability in cell suspension. Air-dried slide preparations can be made from the cell suspensions so that an accurate estimate of the viability of the cells in the original suspension can be made up to 1 week later. Viable cells fluoresce bright green, while nonviable cells are bright red. Furthermore, when FDA-PI staining is compared to trypan blue dye exclusion as a method to determine cell viability, FDA-PI is found to be more consistent over prolonged periods of exposure to the dyes. Therefore, double staining with FDA-PI is a rapid, convenient, and reliable method to determine cell viability.

Animals↗
PubMed1987

Propidium iodide as a nuclear counterstain for immunofluorescence studies on cells in culture.

We describe a rapid procedure using propidium iodide (PI) as a nuclear counterstain in immunofluorescence studies where cell surface or intracellular antigens are localized with fluorescein-conjugated antisera. In fixed monolayer preparations, all cell nuclei fluoresce red and can be seen simultaneously with cellular antigens that fluoresce green. Counterstaining with PI therefore makes possible quantification of the proportion of cells present in culture that stain immunocytochemically for a specific antigen.

Cell Nucleus↗
PubMed1989

Ethidium bromide- and propidium iodide-PTA staining of nucleic acids at the electron microscopic level.

Ultra-thin sections of various tissues were stained with ethidium bromide or propidium iodide, two fluorescent markers widely used for quantitation of nucleic acids. The fluorochromes, tested at different concentrations, were then revealed by incubation of the sections with neutralized phosphotungstic acid. We showed that at the electron microscopic level only nucleic acid-containing structures are revealed. Chromatin, nucleolus, and ribosomes appear to be stained by the end-product of the reaction. Furthermore, controls with proteases and nucleases showed that the staining is related to the binding of the fluorochromes to DNA and RNA and to the subsequent detection of the dyes by neutralized PTA.

Animals↗
PubMed1994

Effects of fixation method on image cytometric measurement of DNA content and distribution in cells stained for fluorescence with propidium iodide.

We performed image cytometric measurements of DNA content and distribution on cycling human HCT-8 cells stained for fluorescence with propidium iodide (PI). Seven different fixation protocols were evaluated for stoichiometry of PI staining and for their ability to preserve in vivo chromatin structure. Bimodal integrated optical intensity (IOI) histograms were obtained with all fixation protocols. Increased accessibility of DNA to the dye was evident in increased values of the IOI at the GI peak. The fixatives studied, in order of increasing accessibility to DNA, were Regaud's Boehm-Sprenger, Carnoy's, air-drying, methanol, ethanol, and acetone/methanol. In general, the coefficient of variation of the IOI within the G1 peak was higher for fixatives where DNA is less accessible. Features describing the spatial distribution of stain exhibited dramatic changes for Boehm-Sprenger fixation, which were consistent with the observation that in vivo conformation of chromatin is best preserved with this method.

Adenocarcinoma↗
PubMed1995

Low-fading immunofluorescence with propidium iodide contrast compared with immunogold light microscopy in whole cells and semi-thin cryosections.

Conventional immunofluorescence produces excellent labeling but has drawbacks such as fading and the need for phase-contrast. Silver-enhanced colloidal gold probes allow counterstaining and permit permanent preparations with no fading if mounted correctly, but the most common limits of this technique are steric hindrance and the artifacts produced by silver enhancement. Our goal was to investigate Herpes simplex virus type 1 (HSV-1) morphogenesis by immunogold cryosection electron microscopy. We therefore needed a sensitive and reproducible immunocytochemical light microscopic method to confirm the immunofluorescence results in whole cells and to screen the cryopreparations before the time-consuming electron microscopic studies. We report data showing that the use of p-phenylenediamine to retard fading and propidium iodide to provide counter-staining results in brilliant fluorescence and contrast, minimal autofluorescence, and invisible fading at least for 5 min exposures, even in preparations with weak antigen presentation. Storage at -20 degrees C provides stable fluorescence. This method is superior to silver-enhanced colloidal gold light microscopy in our investigations.

Cells, Cultured↗
PubMed2004

Assessment of Sarcocystis neurona sporocyst viability and differentiation between viable and nonviable sporocysts using propidium iodide stain.

Sarcocystis neurona has become recognized as the major causative agent of equine protozoal myeloencephalitis (EPM) in the Americas. At least 3 pathogenic species of Sarcocystis, including S. neurona, can be isolated from opossums. Methods are needed to ascertain whether these isolates are viable and capable of causing infections. In this study, the nuclear stain propidium iodide (PI) was used to differentiate between live (viable) and heat-killed (nonviable) S. neurona sporocysts. PI was excluded by live sporocysts but penetrated compromised sporocyst membrane and stained sporozoite nuclei of dead sporocysts. After live and dead sporocysts were mixed at various ratios, the number of unstained sporocysts detected after the staining procedure correlated significantly (r2 = 0.9978) with the expected numbers of live sporocysts. Sporocyst mixtures were also assayed for in vitro excystation and development in tissue cultures. The correlation between the percentage of plaques formed in tissue cultures and the percentage of expected infectious (live) sporocysts in each mixture was r2 = 0.6712. By analysis of variance, no statistically significant difference was measured between the percentage of viable sporocysts and the percentage of infectious sporocysts (P = 0.3902) in each mixture. In addition, there was evidence of a relation between PI impermeability of sporocysts and animal infectivity. These results suggest that the PI dye-exclusion technique can be a useful tool in identifying viability and potential infectivity of S. neurona sporocysts and in differentiating between viable and nonviable sporocysts.

Analysis of Variance↗
PubMed2000

Assessment of secondary necrosis of Jurkat cells using a new microscopic system and double staining method with annexin V and propidium iodide.

Using a new system developed by us for acquiring microscopic images automatically, we compared the morphological changes that apoptotic cells undergo with changes in the staining pattern of annexin V-enhanced green fluorescent protein (AV-EGFP) and propidium iodide (PI) in individual cells. Jurkat cells were treated with 5 mM CaCl2 alone, anti-Fas antibody and heating at 42 degrees C for 30 min or 46 degrees C for 60 min, and then were incubated in medium with 5 mM CaCl2. Time-lapse DNA fragmentation analysis and morphological observation revealed that the anti-Fas antibody and heating at 42 degrees C for 30 min induced typical apoptosis in the cells, and heating at 46 degrees C for 60 min induced typical necrosis. Time-lapse observation of individual cells stained with AV-EGFP and PI confirmed that apoptotic cells were stained at first with AV-EGFP alone, and thereafter also with PI when the cellular membrane ruptured and the cell underwent secondary necrosis. Most of the cells which underwent necrosis were stained simultaneously with AV-EGFP and PI. There was a significant time interval between the staining of individual cells with AV-EGFP, indicating apoptosis, and staining of these cells with PI, which indicated the occurrence of secondary necrosis. These results suggest that time-lapse examinations are necessary to distinguish apoptosis, secondary necrosis and necrosis in cells from one another. This study presents direct evidence that apoptotic cells undergo secondary necrosis, which could be recognized with PI.

Annexin A5↗
PubMed2001

Supravital exposure to propidium iodide identifies apoptosis on adherent cells.

BACKGROUND: Several studies indicate that plasma membrane changes during apoptosis are a general phenomenon. Among the flow cytometric methods to measure apoptosis, the Annexin V assay that detects the membrane exposure of phosphatidylserine (PS) is one of the most commonly used. However, the various treatments used for the detachment of adherent cells generally interfere with the binding of Annexin V to membrane PS, making apoptosis measurement a technical problem. Materials and Methods Apoptosis of different cell lines was investigated by fluorescence microscopy and multiple flow assays designed to assess loss of membrane integrity, translocation of PS, DNA fragmentation, and light scatter changes. Results and Conclusions We show that supravital propidium iodide (PI) assay stains adherent apoptotic cells, allowing flow cytometric quantification. Moreover, supravital exposure to PI without prior permeabilization identifies apoptotic cells as well as Annexin V and permits the simultaneous surface staining by FITC- and PE-conjugated monoclonal antibodies. As in the case of necrotic or permeabilized cells, fluorescence microscopy has revealed that PI staining of apoptotic cells is localized in the nucleus. This suggests that the binding of PI to the DNA/RNA structures is stable enough to withstand the trypsinization and/or washing procedures necessary to detach adherent cells.

Annexin A5↗
PubMed1992

[A rapid measuring technique for allergen-induced IL2 responsiveness of lymphocytes by the propidium iodide-staining method. Detection of the etiological antigen in patients with allergic diseases].

A method for rapidly measuring the interleukin 2 (IL-2)-responsiveness of allergen-stimulated lymphocytes has been newly developed using propidium iodide (PI) staining and drawing ink quenching of the fluid medium fluorescence. There was a linear correlation between the number of PI-stained cells and the fluorescence intensity. The background was less than 5 percent. This fluorochromasia assay reflected the cell number for the quantitative measurement of lymphocyte proliferation. Antigen-activated patient cells added to IL2, showed greater increase in 3H-TdR uptake than IL-2-untreated cells, and were capable of acquiring IL2 responsiveness. Increased numbers of the cells were observed by both the PI- and trypan blue-staining methods. In contrast, unstimulated cells also showed increased 3H-TdR uptake response without increased cell numbers on stimulation with r-IL2 by a 6.8 to 19.3 fold stimulation index compared to the antigen-activated cells. The results indicated that the unstimulated cells in addition with r-IL2 still remained in the initial phase of the DNA-synthetic (S) period through the cell cycle, whereas the activated cells had passed through the post-synthetic gap (C2) and/or cell division at mitosis (M). 3H-TdR uptake of cultured cells usually demonstrates the presence of antigen-sensitized lymphocytes by in vitro proliferative response, and shows an increased stimulation index in 4 or 7 day cultured cells on stimulation with allergens. However, proliferation of some cell populations decreased; furthermore no distinct differences in cell proliferation between allergic and normal lymphocytes were observed, as is usual in this assay, although the present method was capable of measuring increased-IL2 responsiveness of patient lymphocytes. The results indicate that the 3H-TdR uptake method can not be substituted for cell enumeration in the evaluation of the antigen-specificity of induced-IL2 responsiveness of activated cells. Therefore, cell enumeration using the PI-staining method may be preferable in this system. The induced response was observed in lymphocytes from patients with atopic dermatitis, bronchial asthma and/or allergic rhinitis specifically on stimulation with the antigen causing clinical symptoms. The results obtained using the PI-staining method were very similar to those in previous reports where the trypan blue staining method was employed. The present method appears to be capable of rapidly screening etiological antigens for disease and easily monitoring clinical activity.

Allergens↗
PubMed2003

A contribution to examination of propidium iodide and annexin V plasma cells indices in multiple myeloma.

The aim of this study was a contemporaneous measurement and a mutual comparison of plasma cells proliferative activity and grade of apoptosis in patients with monoclonal gammopathy of undetermined significance (MGUS) and various phases of MM i.e. smoldering (SMM), stable/plateau and active (progression/relapse) forms of this disease. The analyzed group of 197 patients consisted of 30 MGUS, 21 SMM, 82 patients examined at the time of MM diagnosis and 64 patients analyzed during various phases of the disease after previous chemotherapy. Plasma cell proliferative activity was measured by means of a propidium iodide index (PC-PI) examined by flow cytometry using a DNA/CD138 double staining technique. For detection of plasma cells entering apoptosis (PC-AI) flow cytometry method with annexin V FITC and MoAb CD138 was used. The individuals with MGUS, SMM and stable/plateau form of MM had overall low levels of PC-PI (M-1.8, 1.7% and 2.1%) and relatively high levels of PC-AI (M-9.1, 10.8 and 9.0%). The correlation between PC-PI and PC-AI was in all the groups mutually highly statistically significant (p=0.000). Analysis of plasma cells proliferative activity (PC-PI) was statistically significant in comparison of MGUS or SMM and versus: patients examined at the time of MM diagnosis (p=0.018 or 0.016); patients evaluated during various phases of MM after previous chemotherapy (p=0.021 or 0.019); stable/plateau MM phase in the cohort of all patients (p=0.017 or 0.040); in the plateau phase after chemotherapy (p=0.008 or 0.024) but insignificant in comparison of MGUS and SMM and with the stable group examined at the time of MM diagnosis. Analysis of the apoptotic process revealed significant differences when comparing PC-AI of SMM but not MGUS group versus all cohort of stable/plateau MM patients (p=0.045); there were also insignificant differences in comparison of MGUS and SMM groupsand versus the stable form of MM measured at the time of MM diagnosis or plateau phase after chemotherapy. There was observed a statistically significant difference in the PC-AI in comparison of SMM group versus group of all patients examined at the time of MM diagnosis (p=0.001) or in various phases of this disease (p=0.015) and the group of MGUS patients compared with patients evaluated at the time of MM diagnosis (p=0.03). Very significant statistical differences of plasma cell proliferative (PC-PI) and apoptotic (PC-AI) activity were found when comparing the levels of both the indices of MGUS, SMM and stable/plateau MM group versus the active (progression/relapse) form of MM marked by a higher level of PC-PI (3.2%, p=0.000) and PC-AI (4.8%, p=0.000) in the whole cohort of MM patients, but also in comparison with both the active forms at the time of MM diagnosis or active forms evaluated during various phases of the disease after chemotherapy. Highly significant inverse relationship between PC-PI versus PC-AI was also revealed in the group of patients in the active (progression/relapse) phase of MM (p=0.000). These results revealed importance of measurement not only of proliferative but also of apoptotic plasma cells indices for a complex evaluation of the cells kinetics of plasma cells compartments in patients with MGUS or MM. This study confirmed the initial hypothesis of a common 'inverse relationship between the proliferative (PC-PI) and the apoptosis activity (PC-AI) in plasma cells compartments in patients with MGUS, smoldering, stable/plateau and active (progression/ relapse) forms of MM'.

Annexin A5↗
PubMedDate not supplied

The assessment of viability in isolated rat hepatocytes subjected to cold or subzero non-freezing preservation protocols using a propidium iodide modified test.

A rapid and simple assay (6 min, two steps) is described for determination of cell viability of hepatocytes subjected to cold preservation protocols. In this method, cells are incubated with the fluorescent marker propidium iodide (PI) and the fluorescence intensity is measured before (direct fluorescence--Fd) and after (total fluorescence--Ft) addition of digitonin, which allows the dye to enter the hepatocytes. The Fd originated from non-viable cells that have membrane damage and taken up PI. The Ft originated from all cells in the sample. The ratio between the two fluorescence values is used as an indicator of cell viability. The assay was challenged versus two classical viability tests: LDH retention and Trypan Blue exclusion. Our assay shows good correlation only with Trypan Blue test. In addition, a fluorescence confocal microscopy protocol was used to evaluate the possible toxicity of PI in hepatocyte suspensions.

Animals↗
PubMed2006

Prognostic significance of plasma cell propidium iodide and annexin-V indices and their mutual ratio in multiple myeloma.

The aim of this study was a contemporaneous measurement of plasma cells proliferative and apoptotic activity in patients examined at the time of multiple myeloma (MM) diagnosis before initiation of chemotherapy, focussed on the following aspects: determination of prognostic significance of plasma cell propidium iodide (PC-PI) and annexin-V FITC (PC-AI) indices; optimal cut off of PC-PI and PC-AI with regard to overall survival; calculation of summary kinetic index of plasma cells (PC-PI/AI ratio) for evaluation of its prognostic importance; determination of an index (out of PC-PI, PC-AI and PC-PI/AI) showing the closest relation to prognosis of multiple myeloma. The analyzed 122 patients fulfilling SWOG multiple myeloma criteria were treated by conventional chemotherapy. Plasma cell proliferative activity was measured by means of PC-PI examined by flow cytometry using a DNA/CD138 double staining technique. For detection of plasma cells entering apoptosis (PC-AI), flow-cytometry method with annexin-V FITC and MoAb CD138 was used. The PC-PI median in 122 patients was 2.6(0.4-4.8)%. The sequence prognostic analysis showed that the optimal PC-PI cut off was 2.9% and displayed a significant relationship with overall survival (OS) (p=0.031). The group of 94 patients had PC-AI median of 5.0(1.4-24.5)%. The best statistical significance of the rate of apoptosis related to overall survival was found at cut off value of 4.4% (p=0.022). The median of overall kinetic index of plasma cells (PC-PI/AI) examined in 94 MM patients was 0.5(0.05-2.60) and the overall kinetic index was found to display a very good relationship to OS at the cut off value of 0.71 (p=0.032). All the three indices expressing various aspects of kinetics of plasma cells allow the stratification of patients into two prognostically different groups with statistically significantly different medians of overall survival: good risk - OS still undeterminable at the time of analysis; bad risk - M: OS was for PC-PI 17 months, for PC-AI 23 months and for PC-PI/AI 16 months. The ratio of both indices, i.e. PC- PI/AI, however did not bring any further contribution to overall survival/prognosis evaluation, when compared with single PC-PI and PC-AI. Results of present study indicates that the evaluation of both proliferation and apoptotic activities of plasma cells is important for prognosis thus extending possibilities of initial stratification of MMpatients into groups with different prognostic risk.

Adult↗
PubMed1985

The use of propidium iodide in cytochemical studies of interphase chromatin structure.

Different cytochemical conditions of using Propidium Iodide, a phenanthridinic fluorochrome specific for double-stranded nucleic acids, have been considered to study some structural aspects of the interphasic chromatin. Some molecular properties of the dye allow to define the structure of chromatin fibre (degree of condensation) by means of thermal denaturation of DNA, fluorochromization after extraction of different chromatin components and fluorochromization in condition of low dye-substrate molar ratio (relative unsaturation of DNA). Different biological situations such as cell specialization, neoplastic transformation and life cycles have been examined choosing some typical models (hepatocytes, nucleated erythrocytes, lymphocytes, endometrial cells).

Animals↗
PubMed1983

Comparison of the cell kill measured by the Hoechst-propidium iodide flow cytometric assay and the colony formation assay.

A flow cytometric live-dead cell assay that uses the dual staining of Hoechst 33342 and propidium iodide (HO-PI) was evaluated for its ability to determine the clonogenicity of treated HeLa cells. The colony-forming assay was used as the reference to determine the capability of the HO-PI assay to measure the proportion of clonogenic cells present in a given population. The viability estimates of both the FCM and trypan blue dye exclusion assays accurately predicted the colony-forming efficiency (CFE) of untreated populations of HeLa cells. However, immediately after treatment with either heat, freeze-thawing, or ionizing radiation the HO-PI assay greatly overestimated the clonogenicity of HeLa cells. This lack of correlation between the FCM determined viability and clonogenic survival was also observed when the cells were heated (45 degrees C, 30 min) and then assayed at 0, 1, 2, 3, 6, 12, 16 or 23 hr after treatment. These data demonstrate that viability as estimated by the HO-PI did not predict survival after acute treatment. In sixty-seven mouse mammary tumour cells, when clonogenicity decreased as a function of time spent in nutrient deprived conditions (chronic treatment), the HO-PI assay again predicted higher CFEs than were measured. Therefore, in these experiments the HO-PI assay could not predict cell death and gave no better measure of cell viability than the trypan blue dye exclusion test.

Benzimidazoles↗