Simultaneous flow cytometric measurement of viability and lymphocyte subset proliferation

A Subpopulation of Monocytes in Normal Human Blood Has Significant Magnetic Susceptibility: Quantification and Potential Implications

The presence of iron in circulating monocytes is well known as they play essential roles in iron recycling. Also, the storage of this metal as well as its incorrect uptake and/or release are important data to diagnose different pathologies. It has been demonstrated that iron storage in human blood cells can be measured through their magnetic behavior with high accuracy; however, the magnetic characteristics of monocytes have not been reported so far to the best of our knowledge. Therefore, in this work, we report, for the first time, the physical and magnetic properties of human monocytes, along with plasma platelets, oxyhemoglobin red blood cells (oxyHb-RBCs), and methemoglobin red blood cells (metHb-RBCs). The different cell populations were separated by Ficoll-density gradient centrifugation, followed by a flow sorting step to isolate monocytes from peripheral blood mononuclear cells. The different fractions were analyzed by Coulter Counter (for determining the size distribution and concentration) and the sorted monocytes were qualitatively analyzed on ImageStream, a state-of-the-art imaging cytometer. The analysis of the Coulter Counter and ImageStream data suggests that although there exists contamination in the monocyte fraction, the integrity of the sorted monocytes appears to be intact and the concentration was high enough to precisely measure their magnetic velocity by Cell Tracking Velocimetry. Surprisingly, monocytes reported the highest magnetic mobility from the four fractions under analysis, with an average magnetic velocity 7.8 times higher than MetHb-RBCs, which is the only type of cells with positive magnetic velocities. This value is equivalent to a susceptibility 2.5 times higher than the value reported by fresh MetHb-RBCs. It should be noted that this is the first study that reports that a subpopulation of human monocytes is much more magnetic than MetHb-RBCs, opening the door to the possible isolation of human monocytes by label-free magnetic techniques. Further, it is suggested that these magnetic monocytes could "contaminate" positively selected, immunomagnetically labeled blood cells (i.e., during a process using magnetically conjugated antibodies targeting cells, such as CD34 positive cells). Conversely, these magnetic monocytes could be inadvertently removed from a desired blood population when one is using a negative magnetic isolation technique to target cells for removal. © 2019 International Society for Advancement of Cytometry.

Isolation of B-cells using Miltenyi MACS bead isolation kits

This article describes the procedures used to isolate pure B-cell populations from whole blood using various Miltenyi magnetic-activated cell sorting (MACS) bead Isolation kits. Such populations are vital for studies investigating the functional capacity of B-cells, as the presence of other cell types may have indirect effects on B-cell function through cell-cell interactions or by secretion of several soluble molecules. B-cells can be isolated by two main approaches: 1) Negative selection—in which B-cells remain “untouched” in their native state; this is advantageous as it is likely that B-cells remain functionally unaltered by this process. 2) Positive selection–in which B-cells are labelled and actively removed from the sample. We used three Negative B-cell isolation kits as well as the Positive B-cell isolation kit from Miltenyi and compared the purity of each of the resulting B-cells fractions. Contamination of isolated B-cell fractions with platelets was the conclusive finding for all of the isolation techniques tested. These results illustrate the inefficiency of current available MACS B-cell isolation kits to produce pure B-cell populations, from which concrete findings can be made. As such we suggest cell sorting as the preferred method for isolating pure B-cells to be used for downstream functional assays.

Necrosis avid near infrared fluorescent cyanines for imaging cell death and their use to monitor therapeutic efficacy in mouse tumor models

Quantification of tumor necrosis in cancer patients is of diagnostic value as the amount of necrosis is correlated with disease prognosis and it could also be used to predict early efficacy of anti-cancer treatments. In the present study, we identified two near infrared fluorescent (NIRF) carboxylated cyanines, HQ5 and IRDye 800CW (800CW), which possess strong necrosis avidity. In vitro studies showed that both dyes selectively bind to cytoplasmic proteins of dead cells that have lost membrane integrity. Affinity for cytoplasmic proteins was confirmed using quantitative structure activity relations modeling. In vivo results, using NIRF and optoacoustic imaging, confirmed the necrosis avid properties of HQ5 and 800CW in a mouse 4T1 breast cancer tumor model of spontaneous necrosis. Finally, in a mouse EL4 lymphoma tumor model, already 24 h post chemotherapy, a significant increase in 800CW fluorescence intensity was observed in treated compared to untreated tumors. In conclusion, we show, for the first time, that the NIRF carboxylated cyanines HQ5 and 800CW possess strong necrosis avid properties in vitro and in vivo. When translated to the clinic, these dyes may be used for diagnostic or prognostic purposes and for monitoring in vivo tumor response early after the start of treatment.

Genome-wide features of neuroendocrine regulation in Drosophila by the basic helix-loop-helix transcription factor DIMMED

Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The dimmed (DIMM) basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMM's activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMM's transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, creb-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of both proximal and distal points in the regulated secretory pathway.

Quality of long-term cryopreserved umbilical cord blood units for hematopoietic cell transplantation

The aim of this study was to evaluate the quality of long-term cryopreserved umbilical cord blood (CB) units for hematopoietic cell transplantation (HCT). The recovery of the number of total nucleated cell (TNC), hematopoietic progenitor cells (HPCs; CD34+ cells, colony-forming units-granulocyte/macrophages [CFU-GMs]), and the percentage of viable cells, CD34+ CD38- cells, and CD34+ CXCR4+ cells of CB units cryopreserved for 10 years for HCT were examined. Eighteen CB units cryopreserved for 10 years (as the study group) and for 1 month (as the control group), respectively, were analyzed. The recovery rate of TNC, CD34+ cells and CFU-GMs were 88.72 ± 16.40, 68.39 ± 18.37 and 42.28 ± 38.16% for the study group and 80.17 ± 14.46, 72.67 ± 20.38 and 49.61 ± 36.39% for the control group (p = 0.106, p = 0.513 and p = 0.559, respectively). There were no significant differences in the recovery rate of TNC, CD34+ cells and CFU-GMs between the study group and the control group. The mean basal percentage of viable cells, CD34+ CD38- cells, and CD34+ CXCR4+ cells after thawing were 83.69 ± 9.45, 9.11 ± 4.13 and 81.65 ± 10.82% for the study group. These results indicate that long-term cryopreservation does not negatively affect the quality of CB units for HCT.

Simultaneous analysis of reactive oxygen species and reduced glutathione content in living cells by polychromatic flow cytometry

Reactive oxygen species (ROS) are continuously produced in the cell as a consequence of aerobic metabolism, and are controlled by several antioxidant mechanisms. An accurate measurement of ROS is essential to evaluate the redox status of the cell, or the effects of molecules with the pro-oxidant or antioxidant activity. Here we report a cytofluorimetric technique for measuring simultaneously, at the single-cell level, hydrogen peroxide and superoxide anion, reduced glutathione (a main intracellular antioxidant) and cell viability. The staining is performed with the fluorescent dyes 2',7'-dichlorodihydrofluorescein diacetate (H2DCFH-DA), hydroethidine (HE), monobromobimane (MBB) and TO-PRO-3. This analysis is possible with new-generation flow cytometers equipped with several light sources (in our case, four lasers and an UV lamp), which excite different fluorochromes. This approach is extremely useful to study the balance between ROS content and antioxidants in cells receiving different stimuli, and to analyze the relationship between oxidative stress and cell death.

Simultaneous characterization of phospho-proteins and cell cycle in activated T cell subsets

Multi-colour flow cytometry is the only technological platform that can analyse the highly complex cellular composition of the immune system in parallel and at a single cell resolution. Analysis of the T cell compartment, in particular, requires the simultaneous measurement of multiple markers in order to account for lineage, phenotype and function. Flow cytometry also enables the analysis of intracellular signalling events. By combining the expression of surface markers, intracellular cytokines, phosphorylated versus unphosphorylated kinases, cell proliferation and DNA profile, mechanistic and kinetic information of subset-specific signalling may be obtained: this has not previously been achieved. Here we present a protocol which permits all of these aspects to be explored simultaneously. By comparing basic procedures previously described we were able to optimise different variables, including the choice of antibody/fluorochrome pairs, permeabilisation, fixation and labelling time, to obtain the best DNA staining of different cell types. We applied this method to study subset-specific signalling related to cytokine production and DNA synthesis in T cells responding to specific antigens.

Ex vivo comparison of microbicide efficacies for preventing HIV-1 genomic integration in intraepithelial vaginal cells

Vaginally applied microbicides hold promise as a strategy to prevent sexual HIV transmission. Several nonspecific microbicides, including the polyanion cellulose sulfate, have been evaluated in large-scale clinical trials but have failed to show significant efficacy. These findings have prompted a renewed search for preclinical testing systems that can predict negative outcomes of microbicide trials. Moreover, the pipeline of potential topical microbicides has been expanded to include antiretroviral agents, such as reverse transcriptase, fusion, and integrase inhibitors. Using a novel ex vivo model of vaginal HIV-1 infection, we compared the prophylactic potentials of two forms of the fusion inhibitor T-20, the CCR5 antagonist TAK-778, the integrase inhibitor 118-D-24, and cellulose sulfate (Ushercell). The T-20 peptide with free N- and C-terminal amino acids was the most efficacious compound, causing significantly greater inhibition of viral genomic integration in intraepithelial vaginal leukocytes, measured by an optimized real-time PCR assay, than the more water-soluble N-acetylated T-20 peptide (Fuzeon) (50% inhibitory concentration [IC50], 0.153 microM versus 51.2 microM [0.687 ng/ml versus 230 ng/ml]; P<0.0001). In contrast, no significant difference in IC50s was noted in peripheral blood cells (IC50, 13.58 microM versus 7.57 microM [61 ng/ml versus 34 ng/ml]; P=0.0614). Cellulose sulfate was the least effective of all the compounds tested (IC50, 1.8 microg/ml). These results highlight the merit of our model for screening the mucosal efficacies of novel microbicides and their formulations and potentially rank ordering candidates for clinical evaluation.

Inhibition of adipocyte differentiation by Nur77, Nurr1, and Nor1

Members of the nuclear receptor 4A (NR4A) subgroup of nuclear receptors have been implicated in the regulation of glucose and lipid metabolism in insulin-sensitive tissues such as liver and skeletal muscle. However, their function in adipocytes is not well defined. Previous studies have reported that these receptors are rapidly up-regulated after treatment of 3T3-L1 preadipocytes with an adipogenic cocktail. We show here that although Nur77 expression is acutely induced by cAMP agonists in 3T3-L1 cells, it is not induced by other adipogenic stimuli, such as peroxisome proliferator-activated receptor-gamma ligands, nor is it induced during the differentiation of 3T3-F442A preadipocytes, suggesting that Nur77 induction is not an obligatory feature of preadipocyte differentiation. We further demonstrate that inflammatory signals that antagonize differentiation, such as TNFalpha and lipopolysaccharide, acutely induce Nur77 expression both in vitro and in vivo. We also show that NR4A expression in adipose tissue is responsive to fasting/refeeding. Retroviral transduction of each of the NR4A receptors (Nur77, Nurr1, and NOR1) into either 3T3-L1 or 3T3-F442A preadipocytes potently inhibits adipogenesis. Interestingly, NR4A-mediated inhibition of adipogenesis cannot be rescued by peroxisome proliferator-activated receptor-gamma overexpression or activation. Transcriptional profiling of Nur77-expressing preadipocytes led to the identification of gap-junction protein alpha1 (Gja1) and tolloid-like 1 (Tll1) as Nur77-responsive genes. Remarkably, retroviral expression of either Gja1 or Tll1 in 3T3-L1 preadipocytes also inhibited adipocyte differentiation, implicating these genes as potential mediators of Nur77's effects on adipogenesis. Finally, we show that Nur77 expression inhibits mitotic clonal expansion of preadipocytes, providing an additional mechanism by which Nur77 may inhibit adipogenesis.

Quality of umbilical cord blood CD34+ cells in a double-compartment freezing bag cryopreserved without a rate-controlled programmed freezer

The aim of this study was to evaluate how a simple method of cryopreservation influences the quality of CD34+ cells in umbilical cord blood (UCB). The cells were dispensed into a double-compartment freezing bag, cryopreserved at -85 degrees C without a rate-controlled programmed freezer, and stored in the liquid phase of nitrogen. The viability of the CD34+ cells before freezing and after thawing was assessed by flow cytometry with 7-aminoactinomycin D and by colony-forming assays. Twenty UCB units cryopreserved for a median of 92 days were analyzed. Mean CD34+ cell viabilities before freezing were 99.8% +/- 0.4% and after thawing were 99.5% +/- 0.8% in large chambers, 99.6% +/- 0.5% in small chambers, and 99.4% +/- 0.6% in sample tubes. The mean values from colony-forming assays of the viable CD34+ cells before freezing were 30.7 +/- 6.8 (colony-forming units-granulocyte-macrophage [CFU-GM] per 100 viable CD34+ cells) and 68.5 +/- 14.8 (total CFUs per 100 viable CD34+ cells). The CFU-GM and total CFU values after thawing were, respectively, 32.7 +/- 9.0 and 66.0 +/- 13.4 in large chambers, 32.4 +/- 8.1 and 64.5 +/- 16.1 in small chambers, and 30.9 +/- 5.4 and 64.7 +/- 12.4 in sample tubes. The results of the colony-forming assays before freezing and after thawing were not significantly different. Our findings overall indicated that our simple method for the cryopreservation of UCB cells without a rate-controlled programmed freezer does not impair the clonogenic capacity of UCB progenitor cells. This cryopreservation method could provide cellular products adequate for hematopoietic stem cell transplantation.

Flow sorting from organ material by intracellular markers

BACKGROUND

Fluorescence-activated cell sorting (FACS) is an attractive technique for gene or protein expression studies in rare cell populations. For cell types where specific surface markers are not known, intracellular markers can be used. However, this approach is currently held to be difficult, as the required fixation and permeabilization may cause protein modification and RNA degradation.

METHODS AND RESULTS

Using the rat thyroid gland as model, rare (parafollicular) and frequent (follicular) endocrine cell types were sorted based on immunostaining for intracellular calcitonin peptide and thyroglobulin protein expression. The sorted cells were compatible with Western blot analysis of proteins, immunoassay detection of calcitonin peptide hormone and RT-PCR.

CONCLUSION

We developed a robust FACS protocol that allows flow sorting of rare cells from dissociated organ material, based on intracellular markers. Our FACS protocol is compatible with downstream analysis of proteins, peptides, and mRNA in the sorted cells.

A flow cytometry procedure for simultaneous characterization of cell DNA content and expression of intracellular protein kinase C-zeta

A selective involvement of protein kinase C-zeta (PKC-zeta) in the events regulating cell proliferation has been recently proposed. Here we report a flow cytometric method allowing the simultaneous association of intracellular PKC-zeta expression or phosphorylation with each cell cycle phase. Current methods for flow cytometry analysis were applied to several cell lines and compared to the method developed in our laboratory. The latter includes 2% paraformaldehyde (PFA), as fixing agent, a permeabilization/saturation step by means of a solution containing 150 mM NaCl, 5 mM EDTA, 50 mM Tris-HCl pH 7.4, 0.05% NP-40, 0.25% lambda-carrageenan and 0.02% NaN3, followed by labelling with a primary antibody (PKC-zeta or P-PKC-zeta) and with the appropriate FITC-conjugated secondary antibody. Cells processed by such a method disclosed no substantial modification of light scattering features with respect to live cells. In addition, stainability with anti-PKC-zeta or anti-P-PKC-zeta antibodies was well preserved while stoichiometric staining of DNA with PI enabled accurate cell cycle analysis. Results show that a distinct up-regulation of P-PKC-zeta in G2/M phase occurs. The method here described, therefore, represents a simple, reproducible and conservative assay for a simultaneous assessment of intracellular PKC or P-PKC modulations within each cell cycle phase.

Characterization of surface interleukin-2 receptor expression on gated populations of peripheral blood mononuclear cells from manatees, Trichechus manatus latirostris

An in vitro system to determine surface interleukin-2 receptor (IL-2R) expression on mitogen-stimulated peripheral blood mononuclear cells (PBMC) from free-ranging manatees, Trichechus manatus latirostris was developed. Human recombinant IL-2, conjugated with a fluorescein dye was used in conjunction with flow cytometric analysis to determine changes in surface expression of IL-2R at sequential times over a 48-h period of in vitro stimulation. Surface expression of IL-2R was detected on manatee PBMC, which also cross-reacted with an anti-feline pan T-cell marker. An expression index (EI) was calculated by comparing mitogen-activated and non-activated PBMC. Based on side- and forward-scatter properties, flow cytometric analysis showed an increase in the number of larger, more granular "lymphoblasts" following concanavalin A (Con A) stimulation. The appearance of lymphoblasts was correlated with an increase in their surface expression of IL-2 receptors. Surface IL-2R expression, in Con A-stimulated PBMC, was detected at 16 h, peaked at 24-36 h, and began to decrease by 48 h. Characterization of the IL-2R expression should provide additional information on the health status of manatees, and the effect of their sub lethal exposure to brevetoxin.

Establishment and optimization of a flow cytometric method for evaluation of viability of CD34+ cells after cryopreservation and comparison with trypan blue exclusion staining

BACKGROUND

Trypan blue exclusion staining is probably the most frequently applied method (Method I) for assessment of viability in peripheral blood progenitor cell grafts after cryopreservation. Alternatively, a flow cytometry-based method (Method II) was established and optimized.

STUDY DESIGN AND METHODS

In a first series of 22 autologous apheresis products, the influence of duration of antibody staining and red cell (RBC) lysis on viability was investigated. In a second series of 21 autologous and 1 allogeneic apheresis products, the effect of omitting the RBC lysis was evaluated. On the basis of the results of the first two series, 155 autologous and 57 allogeneic apheresis products were analyzed with Method I and the now optimized Method II.

RESULTS

Halving the incubation times did not influence the viability of CD45+ or CD34+ cells. Omission of RBC lysis resulted in a significantly (p = 0.022) increased median viability of CD45+ cells (75.8% vs. 71.0%) without any influence on CD34+ cells. In the third series, the median viability of CD34+ cells (96.9%) was significantly (p < 0.0001) higher compared with the viability of CD45+ cells (76.2%) and the viability determined by Method I (86.5%).

CONCLUSION

The viability of CD34+ cells was significantly higher compared with the viability of all white blood cells. The presented cytometry-based method is superior to the standard trypan blue method regarding the number of analyzable cells and documentation, regarding observer independence and standardization; it allows the analysis of the cells of interest for transplantation after minimal sample manipulation.

Interleukin-18 enhances monocyte tumor necrosis factor alpha and interleukin-1beta production induced by direct contact with T lymphocytes: implications in rheumatoid arthritis

OBJECTIVE

At sites of inflammation, T cells exert pathologic effects through direct contact with monocyte/macrophages, inducing massive up-regulation of interleukin-1 (IL-1) and tumor necrosis factor alpha (TNFalpha). We examined the regulatory effects of IL-18 on monocyte activation by direct contact with T lymphocytes in rheumatoid arthritis (RA).

METHODS

Activated T cells were isolated from RA synovial fluid. Resting T cells and monocytes were isolated from peripheral blood mononuclear cells. RA synovial T cells or phytohemagglutinin (PHA)-stimulated T cells were fixed by paraformaldehyde and then cocultured with monocytes at a ratio of 4:1. Levels of TNFalpha, IL-1beta, IL-10, and IL-18 were measured by enzyme-linked immunosorbent assay. Expression of adhesion molecules, IL-18 receptor, and TNF receptors was analyzed by flow cytometry. Expression of NF-kappaB p65, phosphorylated IkappaBalpha, and phosphatidylinositol 3-kinase (PI 3-kinase) p110 was analyzed by Western blotting.

RESULTS

IL-18 dose-dependently enhanced the production of IL-1beta and TNFalpha, but not IL-10, by monocytes following contact with RA synovial T cells or PHA-prestimulated T cells. NF-kappaB inhibitors N-acetyl-L-cysteine and Bay 11-7085 and PI 3-kinase inhibitor LY294002 inhibited the enhancing effects of IL-18, but MAPK p38 inhibitor SB203580, ERK inhibitor PD98059, and JNK inhibitor SP600125 did not. Increased levels of NF-kappaB in the nucleus, phosphorylated IkappaB, and PI 3-kinase were confirmed in monocytes cocultured with PHA-prestimulated T cells, and the levels were further increased by stimulation with IL-18. Neutralizing antibody to IL-18 inhibited monocyte activation induced by direct contact with PHA-prestimulated T cells. Via cell-cell contact, PHA-prestimulated T cells increased autocrine production of IL-18 by monocytes, which was mediated by activation of the NF-kappaB and PI 3-kinase pathways, and up-regulated the expression of the IL-18 receptor in monocytes. IL-18 up-regulated the expression of the TNF receptors vascular cell adhesion molecule 1 (VCAM-1) and intercellular adhesion molecule 1 (ICAM-1) on monocytes. Blocking the binding of the TNF receptors VCAM-1 or ICAM-1 on monocytes to their ligands on stimulated T cells suppressed the IL-18-enhanced production of TNFalpha and IL-1beta in monocytes induced by contact with PHA-prestimulated T cells.

CONCLUSION

IL-18 augments monocyte activation induced by contact with activated T cells in RA synovitis, which is dependent on activation of the NF-kappaB and PI 3-kinase pathways. IL-18 up-regulates the expression of the TNF receptors VCAM-1 and ICAM-1 on monocytes, which mediate the enhancing effects of IL-18 on T cell-monocyte contact.

Optimization of three- and four-color multiparameter DNA analysis in lymphoma specimens

BACKGROUND

Simultaneous analysis of DNA and immunophenotype of lymphoma cells by flow cytometry allows the calculation of the proliferative activity and aneuploidy in even a small lymphoma population. Unfavorable DNA binding characteristics or spectral features of DNA dyes impair the accuracy of multiparameter DNA analysis and limit their clinical application. We describe here a reliable and reproducible application of both three- and four-color multiparameter DNA analysis.

METHODS

After immunostaining of fresh samples of peripheral blood, bone marrow and single cell suspensions of lymph nodes from healthy and lymphoma patients, a methanol fixation for TO-PRO-3 and DRAQ5 staining was tested.

RESULTS

The red-excitable TO-PRO-3 on a FACSCalibur is limited to two-color antigen staining including fluorescein-isothiocyanate and phycoerythrin-labeled monoclonal antibodies due to its broad excitation spectrum. Although DRAQ5 is only applicable to flow cytometers equipped with a single argon laser emitting 488-nm light, its emission spectrum can be easily separated from the FITC, PE, and PE/Texas-Red emissions. DRAQ5 showed almost identical stoichiometric DNA binding characteristics as propidium iodide. Coefficient of variation produced by DRAQ5 staining is in the range of 3.5 and is adequate for detecting aneuploid amd near-diploid cells.

CONCLUSIONS

These advantageous features of DRAQ5 make it a reliable candidate for multiparameter clinical studies.

Five-color flow cytometric analysis of swine lymphocytes for detection of proliferation, apoptosis, viability, and phenotype

BACKGROUND

The objective of this study was to develop a method to simultaneously examine phenotype, proliferation, apoptosis, and death of antigen-stimulated porcine lymphocytes.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from pigs vaccinated with a Brachyspira hyodysenteriae bacterin.

RESULTS

Once isolated, PBMCs were stained with the fluorescent membrane intercalating dye, PKH67, and cultured with or without B. hyodysenteriae whole-cell sonicate antigen. Serial samples of nonstimulated and B. hyodysenteriae-stimulated PBMCs were harvested for flow cytometric analysis. Fluorochrome excitation was performed with spatially separated air-cooled argon and red helium neon laser beams. Five-color analysis included signal detection of PKH67 (proliferation), phycoerythrin (cell surface antigen), Texas Red phycoerythrin tandem (cell surface antigen), allophycocyanin (annexin V), and 7-amino-actinomysin D (7AAD; viability). For analysis, gates were set on live (annexin V(-), 7AAD(-)), intact apoptotic (annexin V(+), 7AAD(dim)), and live plus intact apoptotic (annexin V(+/-), 7AAD(dim/-)) cells, and the phenotypes of PBMCs within these populations were determined during the course of the in vitro response. Dead cells (i.e., 7AAD(bright)) were excluded from the analysis.

CONCLUSION

Application of this method for the determination of porcine lymphocyte subset proliferation is presented.