Rapid single-step method for flow cytometric detection of surface and intracellular antigens using whole blood

Integrative histopathological and immunophenotypical characterisation of the inflammatory microenvironment in spitzoid melanocytic neoplasms

AIMS

The role of inflammation in conventional cutaneous melanoma has been extensively studied, whereas only little is known about the inflammatory microenvironment and immunogenic properties of spitzoid melanocytic neoplasms. The composition of infiltrating immune cells and the architectural distribution of the inflammation, in particular, are still obscure. This is the first study, to our knowledge, to systematically characterise the inflammatory patterns and the leucocyte subsets in spitzoid melanocytic lesions.

METHODS AND RESULTS

We examined 79 spitzoid neoplasms including banal Spitz naevi (SN, n = 50), atypical Spitz tumours (AST, n = 17) and malignant Spitz tumours (MST, n = 12) using histopathological analysis and immunohistochemistry. Spitzoid melanocytic lesions showed a high frequency (67.1%, n = 53 of 79) of inflammation. Four inflammatory patterns were identified according to architectural composition, distribution and intensity of inflammation. The majority of the inflammatory infiltrate corresponded to CD3+ /CD8+ T lymphocytes (56.1%), followed by CD3+ /CD4+ T cells (35.7%) and CD68+ histiocytes (20.3%). CD3+ /TIA-1+ cytotoxic T lymphocytes constituted 3.7% of inflammatory cells. Rarely, CD3+ / granzyme B+ cytotoxic T lymphocytes (2.7%) and CD138+ plasma cells (0.5%) were detected in the infiltrating immune cells. There was no significant difference in the inflammatory cellular composition among the spitzoid melanocytic subgroups (SN versus AST versus MST).

CONCLUSION

Our findings demonstrate that Spitz tumours are highly immunogenic lesions. Inflammation with the presence of lymphocytic aggregates predominated in SN, but was not distinctive for this melanocytic category. A strong and intense inflammation was suggestive of an underlying malignancy. The infiltrating cytotoxic T lymphocyte subsets in Spitz tumours deserve further investigation in larger study cohorts to elucidate prognostic and immuno-oncological therapeutic relevance.

Effect of oral supplementation of Lactobacillus reuteri in reduction of intestinal absorption of aflatoxin B(1) in rats

The goals of this work were to assess the ability of Lactobacillus reuteri to bind aflatoxin B(1) in the intestinal tract and determine its effect on intestinal absorption of the toxin dispensed in either single or multiple doses in a murine model. Male Wistar rats were used, and two experiments were conducted after bacteria were implanted. Experiment one involved a single-oral dose of toxin, and the subsequent flow cytometric analysis of bacteria isolated from the small intestine and treated with specific FITC-labeled AFB(1) antibodies. The second experiment was carried out supplying the toxin in 7 oral sub-doses, and the later quantification of AFB(1)-Lys adducts in blood samples by ELISA assay. The results demonstrated that L. reuteri was able to bind AFB(1) in the intestinal tract, mostly in the duodenum. Furthermore, the AFB(1)-Lys adducts were present at significantly lower levels in those animals receiving AFB(1) plus bacteria than in those receiving only AFB(1). Our findings confirm that probiotic bacteria could act as biological barriers in normal intestinal conditions thereby reducing the bioavailability of AFB(1) ingested orally in a single or multiple doses, thus avoiding its toxic effects.

Harmonization of light scatter and fluorescence flow cytometry profiles obtained after staining peripheral blood leucocytes for cell surface-only versus intracellular antigens with the Fix & Perm reagent

Staining for intracellular markers with the Fix & Perm reagent is associated with variations in the scatter properties of leucocytes, limiting automated analysis of flow cytometry (FCM) data. Here, we investigated those variables significantly contributing to changes in the light scatter, autofluorescence, and bcl2 staining characteristics of peripheral blood (PB) leucocytes, after fixation with Fix & Perm. Our major aim was to evaluate a new mathematical approach for automated harmonization of FCM data from datafiles corresponding to aliquots of a sample treated with cell-surface-only versus Fix & Perm intracellular staining techniques. Overall, neither the anticoagulant used nor sample storage for <24 h showed significant impact on the light scatter and fluorescence properties of PB leucocytes; similarly, the duration of the fixation period (once >15 min were used) had a minimum impact on the FCM properties of PB leucocytes. Conversely, changes in cell/protein concentrations and the fixative/sample (vol/vol) ratio had a clear impact on the light scatter features of some populations of leucocytes. Accordingly, lower cell/protein concentrations were associated with lower scatter values, particularly for the neutrophils. Such changes could be partially corrected through the use of higher fixative to sample volume ratios. Despite the variable changes detected between aliquots of the same sample treated with cell surface-only versus intracellular staining procedures, the new mathematical approach here proposed and evaluated for automated harmonization of common parameters in both datafiles, could correct the FCM profiles of leucocytes derived from cells undergoing conventional fixation/permeabilization procedures, and made them indistinguishable from those corresponding to aliquots of the same sample treated with cell-surface-only staining techniques.

The Ultrastructure of Hybrid Acute Leukemia: A Study of 15 Cases

The objective of this study was to investigate the ultrastructural characteristics of hybrid acute leukemia (HAL). Fifteen cases of HAL were studied by transmission electron microscopy (TEM), focusing on organelles and myeloperoxidase (MPO) reaction of leukemic cells. By TEM, 5 out 15 cases of HAL were consistent with immunophenotyping (3 cases of biphenotypic type, and 2 cases of biclonal type with granulocytes and lymphocytes); 2 cases were suspected as HAL. On other hand, 5 cases of HAL were assigned to ALL, and 2 cases were misinterpreted as M5a and 1 as M4b. Most of the blast cells of biphenotypic HAL showed lymphoid features, except some cases containing MPO positive granules in blasts, while a few cases exhibited monocytic or nonspecific features. TEM offers advantages in the diagnosis of biclonal type HAL and biphenotypic HAL positive for MPO. However, it is difficult to differentiate MPO-negative cases of biphenotypic HAL from ALL and a few cases may be misinterpreted as M5 by TEM.

Significance of transmission electron microscopy in subtyping of monocytic leukemia

The objective of this paper is to produce an ultrastructural classification of acute monocytic leukemia (AML-M5) in relation to clinical behaviors. The ultrastructural characteristics of blasts of the monocytic series were analyzed in 72 M5 patients by transmission electron microscopy (TEM), in terms of their content of typical monoblasts, atypical monoblasts, atypical promonocytes, and typical promonocytes in bone-marrow aspirates. Four kinds of monocytic blasts were identified by cell size and shape, nuclear profile, nucleocytoplasmic ratio, heterochromatin content, nucleolus, granules, vesicles, and Golgi apparatus. Their characteristics of remission rate, cytochemistry, immunophenotype, and cytogenetics were also investigated. The data obtained permitted M5 patients to be divided into monoblast and promonocyte types. Monoblast-type patients expressed weaker monocytic enzymograms and specific antigen staining for CD14 and CD64, compared with promonocyte-type patients. Monoblast patients had higher CR than promonocyte patients. Therefore, TEM subclassification of patients differs from and improves upon the light microscopical criteria for distinguishing monoblasts and promonocytes and has clinical significance.

Ribosome-lamella complex precursors in acute monocytic leukemia: a study of 6 cases

The ribosome-lamella complex (RLC) is a cylindrical structure composed of annular lamella associated particles, regarded as ribosomes, around a central core, which is best known in hairy cell leukemia. RLC has been presumed to originate from aggregating rER and ribosomes. Incomplete and maturing RLC structures have been called RLC precursors (pre-RLC). The present paper investigates the various architectural aspects of pre-RLC and the ultrastructural characteristics of the blasts in 6 cases of acute monocytic leukemia (M5) in which these structures occur. Blasts bearing pre-RLC contained irregular nuclei with less heterochromatin and a prominent nucleolus, and many cytoplasmic organelles in an abundant cytoplasm. The findings indicate that pre-RLC might result from an asymmetrical differentiation of organelles in blasts associated with expression of CD117 and CD56 but default of CD14 in M5.

Comparison of methods for determining zeta-chain associated protein – 70 (ZAP-70) expression in patients with B-cell chronic lymphocytic leukemia (B-CLL)

BACKGROUND

Zeta-chain associated protein of 70kDa (ZAP-70) is the most promising surrogate marker for the immunoglobulin heavy chain variable region (IgV(H)) mutation status in B-cell chronic lymphocytic leukemia (B-CLL). Crespo et al. proposed the detection of ZAP-70 by flow cytometry. Recently several novel monoclonal antibodies appeared on market.

METHODS

We compared different staining methods utilizing monoclonal antibodies (moAb) against ZAP-70: anti-ZAP-70 PE, clone 1E7.2, anti-ZAP-70 PE, clone 17A/P-ZAP70 directly stained with flourochrome as well as anti-ZAP-70 antibody, clone 2F3.2 stained with Zenontrade mark Alexa Fluor(R) 488 Labeling Kit. Additionally different reagents for permeabilization such as IntraPrep, FIX & PERM, Perm/Wash and 70% ethanol/paraformaldehyde were used to find the most clinically relevant and easy assay to determine ZAP-70 expression in B-CLL. Moreover we compared results of ZAP-70 expression assessed by whole blood protocol with those obtained using-peripheral mononuclear cells isolated from whole blood.

RESULTS

Anti-ZAP-70 moAb clone 17A/P-ZAP70 gave elevated results for all B-CLL patients as well as healthy controls. Staining with anti-ZAP-70 moAb clone 1E7.2 and anti-ZAP-70 moAb clone 2F3.2 was effective in distinguishing negative and positive cells for ZAP-70 protein expression. Not statistically significant discrepancies of ZAP-70 expression were noticed between different fixation and permeabilization methods.

CONCLUSION

Basing on results obtained during this study we can recommend use of anti-ZAP-70 PE, clone 1E7.2 moAb utilizing whole blood protocol with commercial kits for permeabilization as an easy method that brings compatible results to the original method proposed by Crespo et al.

Whole blood fixation and permeabilization protocol with red blood cell lysis for flow cytometry of intracellular phosphorylated epitopes in leukocyte subpopulations

BACKGROUND

Previous studies of intracellular expression of phospho-epitopes in human leukocytes using flow cytometry have used erythrocyte removal or lysis before fixation. Because many of the phospho-epitopes of interest are part of signaling networks that respond to the environment and turn over rapidly, the interval and manipulations used to eliminate erythrocytes from samples have the potential to introduce artifacts. We report a procedure to fix samples containing red blood cells with formaldehyde and then remove erythrocytes by lysis. Detection of phospho-Thr 202/Tyr 204-p44/42 extracellular-regulated kinase (ERK) after phorbol ester acetate (PMA) stimulation was used as a model to measure phospho-epitopes in leukocyte populations in whole blood.

METHODS

Normal blood samples were activated with PMA followed by formaldehyde fixation and subsequent treatments with detergents and protein denaturants. The effects of each treatment were monitored by light scatter, selected CD expression intensity, and phosphorylated ERK (pERK) expression.

RESULTS

Red cells could be lysed using 0.1% Triton X-100 after brief fixation of whole blood with 2% or 4% formaldehyde. Light scatter improved as a function of formaldehyde concentration and inversely with MeOH concentration. CD3 signal intensity increased when MeOH concentration was reduced. The ratio of pERK immunofluorescence in PMA-stimulated versus nonstimulated (control) samples was highest with high MeOH (90%) and lowest without MeOH treatment. This pattern is consistent with epitope unmasking by alcohol. The pERK epitope could also be unmasked by treatment with high salt, urea, acid, or heat, but none of these produced the level of unmasking of MeOH and each of these was associated with degradation of light scatter and CD3 staining intensity. The final procedure employed 4% formaldehyde, 0.1% Triton X-100, followed by 50% methanol denaturation. Samples prepared in this way demonstrated good preservation of light scatter and surface immunophenotypic patterns, similar to those obtained using a commercial whole blood/red blood cell lysing system (Q-Prep) and an acceptable PMA-stimulated pERK signal (essentially 100% of CD3+ cells that are pERK positive).

CONCLUSIONS

Brief fixation of whole blood in 4% formaldehyde followed by treatment with Triton X-100 results in erythrocyte lysis and leukocyte light scatter and immunophenotypic features equivalent to those of other commercial lysis reagents. Intracellular pERK staining is significantly improved by treatment with methanol, but levels of MeOH above 50% degrade light scatter and CD3 expression. This protocol (formaldehyde/Triton X-100/MeOH) circumvents potential artifactual changes in phospho-epitopes due to removal of erythrocytes or erythrocyte lysis followed by fixation, and results in a pERK signal that resolves positive from negative cell populations.

Method for localization of sialic acid on cell surface and cell interior in peripheral blood: A pilot study

This article presents a method for identification and localization of cell surface and intracellular sialoglycoconjugates of peripheral blood cells. To reveal cell surface conjugates, a sample of peripheral blood was incubated with lectin after centrifugation and rinsing. For intracellular localization in leukocytes, RBCs were lysed and the membranes were permeabilized prior to cytochemical reaction. Fluorescein isothiocyanate conjugated lectins were used for visualization in fluorescence microscope. All lectins bound specifically to the surface of erythrocytes. Confocal microscopy showed surface and intracellular labeling of permeabilized leukocytes. A part of the signal in eosinophils originated from binding of anionic fluorophore to cationic granular proteins.

Monitoring of monocyte functional state after extracorporeal circulation: a flow cytometry study

BACKGROUND

Cardiovascular surgery with cardiopulmonary bypass (CPB) induces systemic inflammation and postoperative complications depending on pro- and anti-inflammatory mechanisms. Activated polymorphonuclear cells and monocytes may be responsible for morbidity associated with CPB. Knowledge of the monocyte functional state in particular may help to develop protective interventions.

METHODS

Samples were drawn from venous peripheral blood (basal condition, at 4 and 24 h after CPB) and coronary blood (before and after cardioplegic arrest) of 14 patients undergoing cardiac surgery. The following phenotypic and functional parameters of the monocyte population were studied by flow cytometry: surface molecules expression (CD18, CD11a, CD11b, CD14, CD15, CD45, HLA-DR, and Toll-like receptor [TLR]-4), myeloperoxidase (MPO) content, and intracellular cytokine production (tumor necrosis factor [TNF]-alpha, interleukin [IL]-1beta, IL-6, and IL-8).

RESULTS

Cardiac surgery with CPB induced down-modulation of surface molecules expression on peripheral monocytes, especially at 24 h after CPB, for CD18, CD11a, and CD11b (P < 0.003) and for the CD15 adhesive cluster (P = 0.0028) and HLA-DR (P < 0.001). At 4 h after CPB, downregulation was observed for CD14 (P = 0.004), CD45 (P = 0.014), and CD15 (P = 0.0056). A loss of MPO was detected in venous peripheral (at 24 h after CPB, P = 0.01) or coronary (at reperfusion, P < 0.02) blood. The CD15 cluster complex exhibited a down-modulation in coronary blood (at reperfusion, P = 0.0003). Spontaneous intracellular production of IL-1beta, IL-6, and IL-8 decreased at 24 h after CPB (P < 0.05).

CONCLUSIONS

The down-modulation of integrins and adhesive receptor expression and the loss of MPO suggest a strong activation and shedding reaction of circulating monocyte after CPB, further exacerbated by contact with coronary ischemic vessels. The changes of differentiation antigens may reflect the appearance of a partially immature population immediately after CPB. The reduced proinflammatory cytokine production, observed at 24 h after CPB, suggests a functional polarization of circulating monocytes.

Identification of intracellular markers in induced sputum and bronchoalveolar lavage samples in patients with respiratory disorders and healthy persons

Induced sputum and bronchoalveolar lavage (BAL) are widely used for retrieving cells and soluble materials for studies of airway inflammation. Centrifuged cell samples are suitable for immunochemical identification of cellular products. The aim was to determine the optimal fixation procedure to detect intracellular antigens in situ. In immunocytochemistry, an appropriate choice of fixation method is a prerequisite for identification of cells and, consequently, for reliability results. We compared eight fixation and permeabilization methods to detect intracellular antigens in cytocentrifuged cell samples. Four granular proteins specific to eosinophils (eosinophil cationic protein, ECP; eosinophil peroxidase, EPO) and neutrophils (human neutrophil lipocalin, HNL; myeloperoxidase, MPO) were the antigens studied. We found that the organic solvents often used in immunocytochemistry are unsuitable fixatives for detection of these intracellular low-molecular-weight proteins. Treatment with crosslinking fixatives alone resulted in incomplete penetration of antibodies into the cell interiors. Best results were obtained using a commercial reagent Ortho PermeaFix (OPF) for flow cytometry. With this, fixation and permeabilization take place simultaneously OPF-treated cells retained their structural characteristics, and the antibodies studied penetrated both cellular and granule membranes. With OPF treatment, ECP EPO, HNL, and MPO were fixed on their places in granules, and their antigenicity was retained. Correct identification of intracellular proteins is important in characterization of the respiratory inflammatory response in clinical work and research.

A small-volume technique for simultaneous immunophenotyping and apoptosis detection in rat whole blood by four-color flow cytometry

BACKGROUND

Cell permeabilization for the detection of intracellular molecules by flow cytometry is usually incompatible with whole blood. This article describes a new technique for the simultaneous detection of surface antigens and DNA content in rat whole blood.

METHODS

In 20 microl of rat whole blood, DNA staining is obtained by permeabilization of cells using a standard red blood cell lysing reagent (Erythrolyse). Immunophenotyping and apoptosis detection by flow cytometry are achieved by using a combination of three surface markers (CD3, CD4, and CD8alpha) and a DNA binding dye (TO-PRO-3).

RESULTS

After a 24-h incubation of whole blood with 1 microM dexamethasone, apoptotic lymphocytes were clearly distinguishable from normal lymphocytes by their reduced size and DNA content. The dexamethasone-induced percentage of apoptotic cells was 58.9 +/- 4.6 for CD4+ and 77.4 +/- 2.9 for CD8+ T cells, compared with 12.6 +/- 2.7 for CD4+ and 17.2 +/- 3.5 for CD8+ T cells in the absence of dexamethasone (data from 10 animals with duplicate samples).

CONCLUSIONS

We have developed a new technique to permeabilize nucleated cells in microsamples of rat whole blood. The methodology allows simultaneous immunophenotyping and apoptosis detection in rat whole blood.

B-cell antigens within normal and activated human T cells

In this study we compared cell surface staining for human peripheral blood lymphocyte (PBL) CD antigens by flow cytometry, with staining obtained following permeabilization of PBL using the Cytoperm method (Serotec). Six CD antigens (CD20, CD21, CD22, CD32, CD35 and major histocompatibility complex class II antigen) normally found on the surface of B cells, were also found to be expressed within T cells. We also showed, by immunoelectron microscopy, that these inappropriately expressed ('occult') CD antigens are located within cytoplasmic vesicles or within the rough endoplasmic reticulum. Following in vitro activation of T cells a distinct increase in expression of all of these cytoplasmic antigens was observed but staining at the cell surface was, by comparison, weak. We therefore propose that up-regulation of various B-cell CD antigens occurs within the cytoplasm of T cells following activation and that these antigens may be synthesized and released into the fluid-phase as soluble immunoregulatory molecules.

Extensive phenotypic analysis of CD34 subsets in successive collections of mobilized peripheral blood progenitors

The transplantation of mobilized progenitor cells after high-dose chemotherapy shortens haemopoietic engraftment. CD34 cell subsets were examined in 20 consecutive mobilized progenitor cell collections obtained from patients with solid tumours that had not been previously treated. The analysis of CD34 cells was based on the expression of intracellular antigens, surface antigens including CD38, and cell size using multi-dimensional flow cytometry. We also correlated the numbers of stem cell subsets reinfused to haemopoietic recovery. The majority of CD34+ cells expressed CD13 and CD33. A significant proportion was cytoplasmic myeloperoxidase (cMPO) positive. CD34+ MPO+ cells increased significantly in late collections. MPO expression was related to cell size. Cells expressing CD13 also increased in late collections in parallel to CFU-GM count. Small subpopulations of CD34+ CD38+ were committed to B cells, T cells and erythroid cell lineages. A small population expressing the megakaryocytic antigen had a small size and were predominantly CD38-. A minor subpopulation expressed stem cells antigens. These were significantly higher in late collections (CD34+ Thy-1+ and CD34+ CD33-). After mobilization, patients received three cycles of intensive chemotherapy followed by reinfusion of mobilized progenitors (5.45 x 10(6)/kg CD34+ cells, range 3.4-11.88). The numbers of reinfused CD34 cells or the individual subsets did not influence recovery of leucocytes (9 d) or platelets (9 d). In conclusion, the numbers of stem cells and their subsets differed between collections and, in unpretreated patients receiving intensive chemotherapy, there was no delayed engraftment when sufficient numbers of stem cells were reinfused. The recovery period was short and not correlated to any stem cell subsets.

Expression of alpha2-macroglobulin receptor-associated protein in normal human epidermal melanocytes and human melanoma cell lines

Alpha2-Macroglobulin receptor/low-density lipoprotein receptor-related protein is a multifunctional cell surface receptor known to bind and internalize a large number of ligands. alpha2-Macroglobulin receptor-associated protein acts as an intracellular "chaperone" for this receptor, and it has been shown to inhibit binding of all its known ligands. In this paper, we characterize the expression of the receptor-associated protein in both normal human epidermal melanocytes and in six different human melanoma cell lines, by the use of flow cytometry and Western blotting analysis. We show that all the melanoma cell lines and the normal melanocytes express the receptor-associated protein at similar levels, with most located intracellularly. No receptor-associated protein was detected at the cell surface in the melanocytes or in three of the cell lines. However, in two of the melanoma cell lines, large amounts of receptor-associated protein were found on the cell surface, these having the largest amounts of it reported to date; in a further melanoma cell line, there was a small amount at the cell surface. We have also shown that the melanocytes and all the melanoma cell lines express the receptor itself at a wide range of levels, the highest levels of both the cell surface receptor and the cell surface receptor-associated protein being found in one particular melanoma cell line. By growing the cell lines under controlled conditions, we have demonstrated that, although the total cellular content of the receptor is markedly increased at high cell culture density, this treatment has no effect on the level of expression of the receptor-associated protein.

Comparison of seven quantitative assays to assess lymphocyte cell death during HIV infection: measurement of induced apoptosis in anti-Fas-treated Jurkat cells and spontaneous apoptosis in peripheral blood mononuclear cells from children infected with HIV

The study of apoptosis in relation to various human disease states, particularly HIV infection, has seen a tremendous increase in activity. In this article, values obtained by seven different assays, designed to quantify apoptosis and applicable to the study of HIV infection, are compared in two cell systems: (1) stimulus-induced apoptosis in Jurkat cells treated with anti-Fas antibody and (2) spontaneous apoptosis in PBMCs isolated from HIV-infected children. The methods used included measurement of cells with subdiploid DNA content, labeling of DNA strand breaks by the TUNEL reaction, annexin V surface labeling for the detection of exposed phosphatidylserine, cytoplasmic antigen labeling with the apoptosis-specific antibody Apo 2.7, detection of changes in flow cytometric light-scattering properties, trypan blue dye exclusion by light microscopy, and detection of changes in cellular chromatin by fluorescence microscopy. These methods produced well-correlated values in the Jurkat system, whereas the same set of methods produced more discrepant values in the PBMC analyses, especially in those patients with low CD4 counts. Specifically, our results showed that the trypan blue test was unacceptable for quantification of apoptosis during HIV infection, whereas TUNEL, of all the methods tested, showed excellent overall correlation in both cell systems, was highly specific, and matched microscopic observation of the cells. Although many of the methods were suited to the study of a homogeneous cell line, caution must be exercised when examining cell death in a heterogeneous cell mixture from an HIV-infected individual.

Detection of intracellular antigens by flow cytometry: comparison of two chemical methods and microwave heating

Detection of intracellular antigens by flow cytometry requires effective fixation and permeabilization of the cell membrane. This study compares three fixation/permeabilization techniques: two commercial chemical reagents, the ORTHOPermeaFixTM (OPF) and the FIX&PERM Cell Permeabilization Kit® (F&P), and a novel method based on microwave heating (MWH). They have been applied to the detection of two nuclear (p53 and rb/p105) and two cytoplasmic (bcl-2 and mdr-1/gp-170) antigens, using positive- and negative-control cell lines and peripheral blood mononuclear cells. Western blotting was performed as a control of protein expression. For the four antigens assessed, cellular morphology, discrimination between intact cells and debris, percentage of positive cells, and mean fluorescence intensity were examined. For this last parameter, the assessment of the MWH technique was performed using SD and a graphical approach inspired by the concepts described by Bland and Altman (Lancet 1986;346:1085–7) as well as Petersen et al. (Clin Chem 1997;43:2039–46). The statistical analysis shows that MWH is comparable to the commercial methods and that its reproducibility is also equivalent to OPF and F&P. As assessed for some of the most clinically relevant intracytoplasmic and intranuclear antigens, the MWH method appears to be a valuable and inexpensive alternative. It is worth noting that, unlike commercial reagents, MWH altered surface antigens. Interestingly, this feature, which would prevent cell selection on the basis of combined membrane and intracellular epitopes, is associated with a decrease of nonspecific background fluorescence.

Apoptotic Regulation in Primitive Hematopoietic Precursors

Bcl-2 and bcl-xL function as suppressors of programmed cell death. The expression of bcl-2 protein in vivo is associated with long-lived hematopoietic cells such as mature lymphocytes and early myeloid progenitors. Bcl-xL, a homologue of bcl-2, is also expressed in lymphocytes and thymocytes. In contrast, the bcl-2-related proteins (bax, bad, and bak) act by promoting apoptotic cell death as shown from their expression in hematopoietic cell lines. We analyzed the expression of bcl-2 and bcl-x proteins in hematopoietic precursors obtained from various cell sources in adult mobilized peripheral blood collected from 13 patients with solid tumors, 8 adult bone marrow, and 12 umbilical cord blood. The analysis was based on the expression of the proliferation and activation specific antigens, CD38 and class II (HLA-DR). Similarly, we analyzed the expression of bcl-2-related proteins bcl-xL, bax, bad, and bak before and during ex-vivo expansion. Hematopoietic precursors expressing strongly the CD34 antigen (CD34s+) and lacking CD38 or HLA-DR expression were analyzed by using three-color immunofluorescence staining. The majority of CD34+ cells expressed bcl-2 and unexpectedly showed a bimodal distribution of low and high expression. More cells that lacked or expressed low density CD38 expressed low bcl-2 than the more differentiated counterparts (those with high density CD38). Immaturity (ie, little or no HLA-DR) is associated with the expression of low bcl-2 compared with HLA-DR+. However, HLA-DR−/low population contained a lower number of cells expressing low bcl-2 (30% to 40%) than CD38−/low in comparable samples. The hematopoietic precursors with bcl-2low and bcl-2high formed a homogeneous population of undifferentiated lymphoid-like cells having a similar forward scatter. These cells expressed strongly the bcl-xL protein (>95%) but were bax low (4% to 12%), bad low (0% to 0.8%), and bak low (0% to 3%). The expression of apoptosis specific protein (ASP) was also low (3.4% ± 3.1%) as was Annexin V. In addition, the CD34+/CD38−showed low cell cycle activity (<2.2%). Induction of apoptosis by overnight incubation of CD34 cells in serum-deprived medium resulted in the upregulation of bcl-2 as a single population histogram. Thus, these results suggest that in quiescent hematopoietic precursors, the bcl-2 protein plays a less prominent role as a survival promoter than bcl-xL and that the low bcl-2 expression did not promote apoptosis. During day 10 of ex vivo expansion of CD34+cells in liquid culture containing stem cell factor, interleukin-3 (IL-3), IL-6, IL-1β, and erythropoietin, the CD34+/CD38− cells expressed high bcl-2 as a single population histogram, and greater than 90% were bcl-xL high. However, the expression of pro- and apoptotic antigens increased: bax (10% to 15%), bad (5% to 8%), bak (6% to 14%), and ASP (6% to 10%). These results show the importance of monitoring the expression of these proteins when defining the culture conditions for ex vivo expansion.

© 1998 by The American Society of Hematology.

Apoptotic Regulation in Primitive Hematopoietic Precursors

Bcl-2 and bcl-xL function as suppressors of programmed cell death. The expression of bcl-2 protein in vivo is associated with long-lived hematopoietic cells such as mature lymphocytes and early myeloid progenitors. Bcl-xL, a homologue of bcl-2, is also expressed in lymphocytes and thymocytes. In contrast, the bcl-2-related proteins (bax, bad, and bak) act by promoting apoptotic cell death as shown from their expression in hematopoietic cell lines. We analyzed the expression of bcl-2 and bcl-x proteins in hematopoietic precursors obtained from various cell sources in adult mobilized peripheral blood collected from 13 patients with solid tumors, 8 adult bone marrow, and 12 umbilical cord blood. The analysis was based on the expression of the proliferation and activation specific antigens, CD38 and class II (HLA-DR). Similarly, we analyzed the expression of bcl-2-related proteins bcl-xL, bax, bad, and bak before and during ex-vivo expansion. Hematopoietic precursors expressing strongly the CD34 antigen (CD34s+) and lacking CD38 or HLA-DR expression were analyzed by using three-color immunofluorescence staining. The majority of CD34+ cells expressed bcl-2 and unexpectedly showed a bimodal distribution of low and high expression. More cells that lacked or expressed low density CD38 expressed low bcl-2 than the more differentiated counterparts (those with high density CD38). Immaturity (ie, little or no HLA-DR) is associated with the expression of low bcl-2 compared with HLA-DR+. However, HLA-DR−/low population contained a lower number of cells expressing low bcl-2 (30% to 40%) than CD38−/low in comparable samples. The hematopoietic precursors with bcl-2low and bcl-2high formed a homogeneous population of undifferentiated lymphoid-like cells having a similar forward scatter. These cells expressed strongly the bcl-xL protein (&gt;95%) but were bax low (4% to 12%), bad low (0% to 0.8%), and bak low (0% to 3%). The expression of apoptosis specific protein (ASP) was also low (3.4% ± 3.1%) as was Annexin V. In addition, the CD34+/CD38−showed low cell cycle activity (&lt;2.2%). Induction of apoptosis by overnight incubation of CD34 cells in serum-deprived medium resulted in the upregulation of bcl-2 as a single population histogram. Thus, these results suggest that in quiescent hematopoietic precursors, the bcl-2 protein plays a less prominent role as a survival promoter than bcl-xL and that the low bcl-2 expression did not promote apoptosis. During day 10 of ex vivo expansion of CD34+cells in liquid culture containing stem cell factor, interleukin-3 (IL-3), IL-6, IL-1β, and erythropoietin, the CD34+/CD38− cells expressed high bcl-2 as a single population histogram, and greater than 90% were bcl-xL high. However, the expression of pro- and apoptotic antigens increased: bax (10% to 15%), bad (5% to 8%), bak (6% to 14%), and ASP (6% to 10%). These results show the importance of monitoring the expression of these proteins when defining the culture conditions for ex vivo expansion.

© 1998 by The American Society of Hematology.

A novel, rapid in cell RNA amplification technique for the detection of low copy mRNA transcripts

Growing interest now focuses on improvements of in situ polymerase chain reaction (PCR) technology for the detection of DNA and RNA cellular sequences. In this study, reverse transcription PCR in situ hybridisation (RT PCR-ISH) was developed and used to determine gene expression of pyruvate dehydrogenase in a cell model system, using human peripheral blood lymphocytes (PBLs). The success of in cell RNA amplification depends on the type of cell/tissue fixation, cell permeabilisation, and the efficiency of reverse transcription and cDNA amplification. This paper presents new approaches to overcome the critical aspects of fixation, permeabilisation, and reverse transcription when performing in cell RNA amplification. A novel fixative, "Permeafix", possessing fixative and permeabilisation properties, was used for cell fixation procedures. "Permeafix" obviated the need for pre-amplification proteolysis, facilitating entry of PCR reagents to target sequences within the cell. In addition, a simple on step RNA in cell amplification protocol using recombinant Thermus thermophilus (rTth) DNA polymerase, which reverse transcribes mRNA efficiently to cDNA and then catalyses cDNA amplification, was used. The value of a semi-junctional primer system for in cell gene expression studies, without the need to perform DNase digestion, is demonstrated.

Single-cell cytokine profiles in normal humans: comparison of flow cytometric reagents and stimulation protocols

Cytokines are produced and function at a micro environmental level: intracellular assessment has only recently become practically feasible. We used 3-color flow cytometry to examine surface and cytoplasmic antigens on peripheral blood lymphocytes of 18 normal donors, assessing the applicability/comparability of various directly conjugated anti-human cytokine reagents and stimulation protocols using separated cells or whole blood preparations. Interdonor variability far exceeded variability due to reagent or stimulation and separation techniques. Based on all results with various reagents, post 4-5.5 h stimulation with PHA/PMA/ionomycin, the range of the percents of T lymphocytes producing various cytokines included: gamma-IFN-13.2-65.0%, IL-2-10.0-56.7%, and TNF-alpha-17.1-79.2%. Compared to CD8+ cells, CD4+ cells more often expressed IL-2 (mean 45.7% of CD4 + vs. 21.4% of CD8+ p < 0.0001), less often expressed gamma-IFN (18.5% vs. 55.3%, p < 0.0001), and did not differ in TNF-alpha expression (52.9% vs. 59.4%). Of T cells producing gamma-IFN, 64.8-100.0% also produced TNF-alpha 3.5-100.0%, IL-2. Of T cells producing IL-2, 6.0-63.9% also produced gamma-IFN and 37.6-100.0%, TNF-alpha. These results demonstrate the broad spectrum of cytokine patterns in normal human adults, as well as the usefulness and limitations of various currently available cytokine products.