The detection of intracytoplasmic interleukin-1 alpha, interleukin-1 beta and tumour necrosis factor alpha expression in human monocytes using two colour immunofluorescence flow cytometry

Inflammatory stimuli differentially modulate the transcription of paracrine signaling molecules of equine bone marrow multipotent mesenchymal stromal cells

OBJECTIVE

Osteoarthritis (OA) is a degenerative disease of joint tissues that causes articular cartilage erosion, osteophytosis and loss of function due to pain. Inflammation and inflammatory cytokines in synovial fluid (SF) contribute to OA progression. Intra-articular (IA) injections of multipotent mesenchymal stromal cells (MSCs) are employed to treat OA in both humans and animals. MSCs secrete paracrine pro-inflammatory and anabolic signaling molecules that promote tissue repair. The objective of this study was to investigate the effects of OASF on the gene expression of paracrine signaling molecules by MSCs.

METHODS

The effects of Lipopolysaccharide (LPS) and interleukin (IL)-1β as well as both normal (N) and osteoarthritis (OA) SF stimulations on the expression of paracrine pro-inflammatory (tumor necrosis factor (TNF)-α, IL-1β, IL-8), modulatory (IL-6) and anabolic (vascular endothelial growth factor (VEGF), transforming growth factor (TGF)-β1 and insulin-like growth factor (IGF)-1) signaling molecules by equine bone marrow multipotent mesenchymal stromal cells (eBM-MSCs) was investigated employing reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

In contrast with NSF, OASF significantly up-regulated the expression of VEGF in eBM-MSCs. Both NSF and OASF significantly down-regulated the expression of IL-1β. LPS and IL-1β significantly increased the expression of pro-inflammatory cytokines (TNF-α, IL-8 and IL-6; and IL-1β and IL-8 respectively).

DISCUSSION

We conclude that the transcription of paracrine signaling molecules in eBM-MSCs is modulated by SF. Furthermore, OA alters the properties of SF and the response of eBM-MSCs. Finally, the effects of LPS or IL-1β stimulation are distinct to that observed following stimulations with OASF.

From model cell line to in vivo gene expression: disease-related intestinal gene expression in IBD

Crohn's disease (CD) and ulcerative colitis (UC) are subforms of inflammatory bowel diseases (IBD). Genetic and environmental factors influencing the onset and course of the diseases have been recently identified. This study uses a two-step approach to detect genes involved in the pathogenesis of IBD by microarray analysis and real-time PCR (RT-PCR). In a first step, microarray expression screening was used to obtain tumour necrosis factor-alpha (TNF-alpha) induction profiles of two human cell lines to represent the tissue cell types involved in IBD. In a second step, a subset of differentially expressed genes was examined by real-time PCR in intestinal biopsy samples of normal controls (NC) compared with UC and CD patients, as well as to a cohort of patients suffering from intestinal diseases other than IBD. Data were obtained from 88 CD, 88 UC, 53 non-IBD patients (inflammatory control), DC and 45 NC individuals. The experimental design enabled the identification of disease-specific expressed genes. DnaJ (Hsp40) homologue, subfamily B, member 5 (DNAJB5) was downregulated in intestinal biopsy samples of the UC cohort compared with NC. A difference in JUNB expression levels was observed by comparing biopsy samples from inflamed and non-inflamed areas of UC patients. Transcript expression differences between IBD and control cohorts were found by examining histamine N-methyltransferase (HNMT), interleukin-1A (IL-1A) and proplatelet basic protein (PPBP) expression. The experimental procedure represents an approach to identify disease-relevant genes, which is applicable to any disease where appropriate model systems are available.

Effects of a short-course of amoxicillin/clavulanic acid on systemic and mucosal immunity in healthy adult humans

Although amoxicillin/clavulanic acid (AMC) is the most frequently administered antibiotic in France, its in vivo effects on immunity in healthy adults have never, to our knowledge, been described. Eighteen healthy adult male volunteers, 25+/-6 years old, were treated for 5 days with oral amoxicillin (1 g) /clavulanate potassium (125 mg), two times daily. Systemic and local intestinal immunity parameters were sequentially explored before, during and after the antibiotic treatment. No significant differences were obtained for transudation markers (albumin and alpha1-antitrypsin) in sera, feces and saliva, showing that AMC did not induce inflammatory reaction. Phagocytosis, peripheral blood cell subsets, intracellular interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha production by natural killer (NK) cells and cytotoxic T lymphocytes, intracellular TNF-alpha production by monocytes showed no significant differences throughout the trial. In fecal outputs, no significant differences were found in secretory immunoglobulin A (S-IgA), lactoferrin (Lf), lysozyme (Lz) and transforming growth factor (TGF)-beta1. In sera, concentrations of total IgA (T-IgA), S-IgA, IgM, Lf and Lz did not show any significant variations throughout the study, whereas concentrations of IgG were slightly but significantly reduced 15 days after AMC treatment. In saliva, concentrations of T-IgA were slightly but significantly higher, whereas S-IgA concentrations were unchanged. Our results showed that oral AMC intake did not induce any significant adverse effects on immunity in adult humans.

Impairment of innate cellular response to in vitro stimuli in patients on continuous ambulatory peritoneal dialysis

BACKGROUND

Most crucial in the initial stages of host defence against invading micro-organisms is innate immunity, in which peripheral mononuclear cells, in particular cytokines, are pivotal. Mortality from infections is high in dialysis patients, but it remains unclear if this arises from the ineffectiveness of innate immune mechanisms.

METHODS

In 20 haemodialysis (HD) patients, 20 patients on continuous ambulatory peritoneal dialysis (CAPD), and 15 age-matched controls, we studied cytokine production by monocytes and helper T-cells in response to in vitro stimuli. The most important early-response cytokines for innate immunity, tumour necrosis factor (TNF)-alpha and interleukin (IL)-1beta, were tested in monocytes, and interferon-gamma and IL-4 were studied as indicators of polarization of helper T-cells into type 1 and type 2 cells. Peripheral blood cells stimulated with lipopolysaccharide or mitogen were labelled with anti-CD14+ and -CD4+ antibodies and then subjected to intracellular cytokine staining and flow cytometry.

RESULTS

CAPD patients showed significantly reduced synthesis of TNF-alpha and IL-1beta and inhibited T helper phenotype development compared with HD patients and control subjects. In contrast, HD patients showed an unaltered monokine response and a marked polarization of helper T-cells towards the type 1 phenotype. We also found that a single HD treatment potentiated monocytes to synthesize TNF-alpha.

CONCLUSIONS

Circulating immune cells in CAPD patients may be hyporeactive against infections, indicating an unfavourable innate host defence.

Patterns of intracellular cytokines in CD4 and CD8 T cells from patients with mycobacterial infections

Using a short-term bulk culture protocol designed for an intracellular-staining method based on a flow cytometry approach to the frequencies of cytokine-producing cells from tuberculosis and leprosy patients, we found distinct patterns of T cell subset expression. The method also reveals the profile of peak cytokine production and can provide simultaneous information about the phenotype of cytokine-producing cells, providing a reliable assay for monitoring the immunity of these patients. The immune response of Mycobacterium leprae and purified protein derivative (PPD) in vitro to a panel of mycobacteria-infected patients from an endemic area was assessed in primary mononuclear cell cultures. The kinetics and source of the cytokine pattern were measured at the single-cell level. IFN-gamma-, TNF-alpha-, IL-4- and IL-10-secreting T cells were intracytoplasmic evaluated in an attempt to identify M. leprae- and PPD-specific cells directly from the peripheral blood. The analysis by this approach indicated that TNF-alpha was the first (8 h) to be produced, followed by IFN-gamma (16 h), IL-10 (20 h) and IL-4 (24 h), and double-staining experiments confirmed that CD4+ were a greater source of TNF-alpha than of CD8+ T cells (P < 0.05). Both T cell subsets secreted similar amounts of IFN-gamma. We conclude that the protocol permits rapid evaluation of cytokine production by different T cell populations. The method can also be used to define immune status in non-infected and contact individuals.

Monocytes are primed to produce the Th1 type cytokine IL-12 in normal human pregnancy: an intracellular flow cytometric analysis of peripheral blood mononuclear cells

This paper considers both monocytes and peripheral blood lymphocytes as potential targets for maternal immunological modulation in pregnancy. Peripheral blood mononuclear cells (PBMCs) from non-pregnant and normal pregnant donors were stimulated in vitro, and cytokine production detected intracellularly by flow cytometry. It was found that monocyte production of TNF-alpha was unaltered in pregnancy, while production of IL-12 was significantly enhanced. In contrast, production of the Th1 type cytokine IFN-gamma was suppressed in the lymphocyte subsets: CD4+ T helper cells and CD56+ NK cells. Production of the Th2 type cytokine IL-4 in CD4+ cells was not significantly altered in pregnancy. These data suggest that the concept that pregnancy is a 'Th2 phenomenon' cannot be generalized to the function of all aspects of maternal cellular immunity as, paradoxically, circulating monocytes are 'primed' to produce the Th1 cytokine IL-12. Furthermore, these data support the hypothesis that components of maternal innate immunity are activated in normal pregnancy.

Generation of a monoclonal antibody that blocks epithelial binding of unopsonized particles

Alveolar macrophages (AMs) and epithelial cells (ECs) are the first cells in the lung to encounter inhaled environmental particles. The initial interaction between AMs and particles is mediated by specific scavenger receptors, but the nature of the structure(s) on ECs that also bind particles has not been well-described. To characterize the nature of the EC particle receptor, we screened a panel of mouse anti-human EC hybridomas for functional blockade of EC particle binding. This strategy identified a monoclonal antibody (MAb) (EPR1) that blocks binding of titanium dioxide (TiO(2)) particles to the EC line which served as the immunogen (A549), as well as to other EC lines (Beas 2-B, HTB54, HeLa, and MDA-MB-435S). EPR1 demonstrated specific labeling of ECs using immunohistology techniques and its expression could be quantitated by flow cytometry of permeabilized ECs in suspension. MAbs such as EPR1 may prove useful in further analysis of receptors for inhaled particles on lung epithelial cells.

Predominance of type-2 immune response in idiopathic membranous nephropathy. Cytoplasmic cytokine analysis

BACKGROUND

The Th1/Th2 paradigm is proving increasingly useful in the understanding of infectious diseases and many autoimmune diseases. Th1 cells predominantly produce interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) and are instrumental in initiating delayed-type hypersensitivity and activating macrophages. Th2 cells secrete other cytokines, such as IL-4, IL-5, IL-10 and IL-13 that trigger B-cell activation and immunoglobulin synthesis. It has been shown that in patients with membranous nephropathy, there may be a predominance of Th2, because of the presence of IgG, particularly IgG4, which belongs to a subclass of the type-2 immune response, and complement deposits in glomeruli. In this study, we investigated the immunoresponse of helper T cells, i.e. Th predominance in patients with idiopathic membranous nephropathy.

METHODS

We used flow cytometry to assess the levels of circulating Th cells in patients with idiopathic membranous nephropathy (n = 8) and in normal individuals (n = 23) based on the expression of intracellular type-1 and type-2 cytokines. Because the production of each of these cytokines has a specific time course, we observed the cytokine synthesis at 3, 6, 9 and 12 h after stimulation.

RESULTS

The percentages of IL-2+/CD4+ cells from patients with idiopathic membranous nephropathy were significantly lower than those from normal individuals at 6, 9 and 12 h, with the difference becoming more significant over time. IFN-gamma+/CD4+ cells and IL-4+/CD4+ cells were not significantly different between the two groups. In patients with idiopathic membranous nephropathy, the percentages of IL-10+/CD4+ cells were significantly higher than those in normal individuals at each point in time.

CONCLUSION

Increased IL-10-producing Th cells may lead to suppression of delayed-type hypersensitivity and activate suppressor cells and IgG4 synthesis, resulting in idiopathic membranous nephropathy.

Intra-amniotic injection of IL-1 induces inflammation and maturation in fetal sheep lung

Antenatal inflammation may be an important triggering event in the pathogenesis of bronchopulmonary dysplasia but may also accelerate fetal lung maturation. We examined the effects of intra-amniotic (IA) interleukin (IL)-1 alpha and IL-1 beta on maturation of the fetal sheep lung. These cytokine effects were compared with IA endotoxin, a potent proinflammatory stimulus that accelerated lung maturation. Date-bred ewes received 15 or 150 microg recombinant ovine IL-1 alpha or IL-1 beta or 10 mg Escherichia coli endotoxin by IA injection at 118 days gestation (term = 150 days), and fetuses were delivered at 125 days. IL-1 alpha and IL-1 beta improved lung function and increased alveolar saturated phosphatidylcholine (Sat PC) and surfactant protein mRNA expression at the higher dose. The maturation response to IL-1 alpha was greater than that to IL-1 beta, which was similar to endotoxin response. Inflammation was also more pronounced after IL-1 alpha treatment. Only endotoxin animals had residual inflammation of the fetal membranes at 7 days. Lung compliance, lung volume, and alveolar Sat PC were positively correlated with residual alveolar wash leukocyte numbers 7 days after IL-1 treatment, suggesting a link between lung inflammation and maturation.

Th2 predominance at the single-cell level in patients with IgA nephropathy

BACKGROUND

Abnormalities of lymphocyte function have been reported to be involved in the pathogenesis of IgA nephropathy (IgA-N). The aim of this study was to investigate helper T (Th) predominance at the single-cell level, one of the abnormalities of lymphocyte function in IgA-N.

METHODS

Using flowcytometry, we assessed the levels of circulating Th cells in IgA-N patients (n=30), and in normal individuals (n=30) based on the expression of intracellular Th1 cytokines for interleukin-2 (IL-2) and interferon-gamma (IFN-gamma), and of intracellular Th2 cytokines for IL-4, IL-10, and IL-13. Because the production of each cytokine had a specific time course, we examined cytokine synthesis at 3, 6, 9, and 12 h after stimulation.

RESULTS

The percentages of IL-2-positive Th cells from IgA-N patients were significantly lower than in normal individuals at 6, 9, and 12 h, with the difference becoming greater with time. The number of IFN-gamma-positive Th cells in IgA-N patients was significantly lower than in normal individuals at 9 h, and the number of IFN-gamma-positive Th cells increased more at 12 h than at 3 h in both groups. IL-4 and IL-13 expression was increased in patients with IgA-N at 6 h compared with normal individuals. In IgA-N patients, the percentage of IL-10-positive Th cells was significantly higher than that in normal individuals at each time-point.

CONCLUSION

A polarization toward Th2 response at the stimulated lymphocyte level may lead to immune abnormalities in IgA-N.

Intra-CNS activation by antigen-specific T lymphocytes in experimental autoimmune encephalomyelitis

Identification and quantitation of autoreactive T lymphocytes is crucial in order to understand the pathogenesis of autoimmune diseases. We used flow cytometry to analyze autoantigen-specific T cellular responses in the well characterized rat experimental autoimmune encephalomyelitis (EAE) model. Cells isolated from both the central nervous system (CNS) tissue and peripheral lymph nodes were analyzed directly ex vivo or after short term in vitro culture with specific autoantigen. CNS infiltrating T lymphocytes displaying an interferon-gamma response to selected encephalitogenic myelin protein epitopes were measured kinetically during an individual disease episode and also between relapses in a chronic rat EAE model. One of the EAE models used displays a restriction towards TCRBV8S2 chain usage by the encephalitogenic T cells. In this model, in vitro production of intracellular interferon-gamma was selectively detected within this T cell subset derived from both the CNS and peripheral lymph nodes. Furthermore, antigen-specific cells infiltrating the CNS in this model produced several-fold higher amounts of interferon-gamma upon antigen stimulation and displayed a significantly increased in vivo proliferation compared with peripheral lymphocytes. These data thus directly demonstrates that T cells stimulated by a specific autoantigen in the periphery primarily acquire effector functions in the cellular environment of the target organ of the autoantigen.

Detection of intracellular interleukin-2 production in peripheral T lymphocytes by flow cytometry in patients with pancreatobiliary malignancies

BACKGROUND AND AIMS

To date, it has been reported that cellular immunity is decreased in patients with cancer and investigations into cytokine production has been insufficient. Therefore, we examined intracellular cytokine production by using flow cytometry in patients with cancer and discussed the reasons for the impairment of their immune system.

METHODS

Eleven patients with hepatobiliary malignancies (68.5+/-11.8 years of age), eight age-matched controls (70.0+/-12.0 years of age) and 10 young volunteers (31.9+/-3.1 years of age) were used in the present study. Stimulated peripheral blood mononuclear cells from these patients were stained with fluorescence-labeled anticytokine monoclonal antibodies and analyzed with a Fluorescence activated cell sorter (FAC)Scan.

RESULTS

The percentage of positively stained T cells was calculated and compared with controls. Repeated measured ANOVA was used for statistical analysis. Interleukin (IL)-2 production was significantly decreased in patients with cancer compared to controls (P=0.0122), and it may suggest decreased cellular immune activity of the patients. Simultaneously, spontaneous intracellular IL-4 production was observed in patients and age-matched controls, but levels were significantly increased when compared with the young volunteers (P=0.0052, P=0.031, respectively).

CONCLUSIONS

It was of interest that spontaneous intracellular IL-4 production was detected in elderly subjects.

Evaluation of microspheres containing cytokine neutralizing antibodies in endotoxemia

Albumin microspheres are efficient carriers for delivering therapeutic agents to macrophages. In response to endotoxin, macrophages release tumor necrosis factor alpha (TNF alpha) and interleukin-1-beta (IL-1 beta). Blocking the effects of TNF alpha and IL-1 beta decreased lethality due to endotoxin-induced shock. In this study, we compared the efficacy of the microsphere form of TNF alpha and/or IL-1 beta neutralizing antibodies (NAs) with the free form of TNF alpha and/or IL-1 beta NA in preventing lethality due to endotoxemia and evaluated the duration of blockade by the microsphere form of TNF alpha and/or IL-1 beta NA on endotoxin-induced cytokine release. The results indicate that the microsphere form of TNF alpha and/or IL-1 beta NA protected 80% of the rats from lethal endotoxemia, while none of the rats that received the free from of TNF beta and/or IL-1 beta NA survived longer than 48 hr. The microsphere form of TNF alpha and/or IL-1 beta NA attenuated endotoxin-induced cytokine release more potently than the free form of TNF alpha and/or IL-1 beta NA in vivo. In vitro, the microsphere form of TNF alpha and/or IL-1 beta NA blocked endotoxin-induced cytokine release for at least 24 hr. Higher efficacy of the microsphere form of NA in reducing mortality and blocking cytokine release makes it more therapeutically advantageous than the free form of NA in the treatment of lethal endotoxemia.

Incorporation of cells into an ELISA system enhances antigen-driven lymphokine detection

The ability to measure successfully the levels of Th1 or Th2 cytokines during an in vitro antigen-driven, polyclonal T-cell response has proven to be more difficult than expected. Here we describe the development of a highly sensitive cell-based ELISA (celELISA) technique for the detection of murine Th1 and Th2 cytokines. The celELISA combines the quantification aspects of the conventional sandwich ELISA with the sensitivity of the ELISPOT assay. The celELISA was particularly useful for the improved detection of IL-2, IL-4, and to a lessor extent, IFN-gamma.

Detection of intracellular interleukin-8 in human mast cells: flow cytometry as a guide for immunoelectron microscopy

The chemokine interleukin-8 (IL-8) mediates infiltration and adhesion of neutrophils during inflammatory processes. We have previously shown that this cytokine can be produced and released by normal and leukemic human mast cells (HMC-1 cells). To assess whether and to what extent this cytokine is stored intracellularly, we investigated production and localization of IL-8 at the single-cell level by combined use of flow cytometry (FACS) and immunoelectron microscopy. Conditions necessary for optimal fixation and permeabilization of HMC-1 cells were determined by measuring changes in cell-specific light scatter parameters and by estimating cellular uptake of propidiumiodide (PI). In this way, we were able to detect IL-8 with a monoclonal antibody in stimulated cells that were microwave-fixed with a combination of paraformaldehyde (4%) and glutaraldehyde (0.1%), followed by permeabilization with saponin (0.025%). FACS analysis revealed time-dependent synthesis of IL-8 with at most 50% positively stained cells at 8-12 hr after stimulation. For pre-embedding immunogold electron microscopy, cells were treated according to the protocol established by flow cytometry. IL-8 was found to be located in specific cytoplasmic, electron-dense granules of stimulated HMC-1 cells. These results confirm and extend our previous findings by demonstrating IL-8 expression in HMC-1 cells at the single-cell level. In addition, we propose that quantitative FACS can be reliably used in a timesaving manner to establish appropriate conditions for pre-embedding immunoelectron microscopy of intracellular antigens.

The effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on tumor necrosis factor (TNF) production by peritoneal cells

Recent studies in mice have demonstrated that TNF plays a critical role in mediating the TCDD-induced enhanced inflammatory response to intraperitoneal (i.p.) sheep red blood cells. The current studies were designed to evaluate the effects of TCDD on TNF production by ex-vivo peritoneal cells and a peritoneal macrophage cell line (IC-21) stimulated with LPS. In support of the hypothesis that TCDD can act directly on the peritoneal macrophage to increase TNF production, following pretreatment with TCDD, both ex-vivo peritoneal cells and IC-21 cells produced increased levels of bioactive TNF when stimulated with LPS. Flow cytometric analyses of IC-21 cells indicate that TCDD exposure increases intracellular production and secretion of TNF but does not alter levels of membrane associated TNF.

A novel method of microwave treatment for detection of cytoplasmic and nuclear antigens by flow cytometry

Flow cytometry has recently become a useful technique for the quantitative analysis of cytoplasmic and nuclear antigens. We report here a rapid, simple, reproducible, and sensitive method for the simultaneous detection of cytoplasmic and nuclear antigens by flow cytometry. This technique involves the treatment of cell suspensions with 60 s of microwave oven heating after fixation with 2% paraformaldehyde. Following this treatment a number of cytoplasmic and nuclear antigens were detected on the human myelomonocytic cell line U937 (CD68, PCNA and Ki-67), peripheral blood leukocytes from both normal donors and leukemia patients (CD68, lipocortin-1 and PCNA) and a rat mesangial cell line 1097 (desmin, alpha-smooth muscle actin) using a standard indirect immunofluorescent staining with mouse monoclonal antibodies (mAbs). There are several advantages of this technique over the routinely used methods currently available. Firstly, microwave treatment is a rapid, simple, and reproducible method, which largely reduces both time and cost expenditure, and makes this technique widely available for flow cytometric analysis in many areas of diagnostic and research purposes. Secondly, microwave treatment produces optimal results for simultaneous detection of both cytoplasmic (CD68, lipocortin-1, desmin, alpha-smooth actin) and nuclear (PCNA, Ki67) antigens. Thirdly, microwave treatment also produces a discrete profile for DNA content analysis. Finally, microwaving retains a clear discrimination between cells and debris as measured by light scatter. This study demonstrates that microwave treatment is a powerful technique which will be particularly applicable to flow cytometric analysis in the detection of many cytoplasmic and nuclear antigens.

Inactivated influenza virus, when presented on dendritic cells, elicits human CD8+ cytolytic T cell responses

Inactivated or subunit virus preparations have been excellent vaccines for inducing antibody responses. Generation of cytolytic T cell responses, however, is thought to require replicating virus, primarily to provide sufficiently large amounts of cytoplasmic proteins for processing and presentation on major histocompatibility complex class I molecules by antigen-presenting cells. Potent human CD8+ cytolytic T cell responses to live replicating influenza A virus are generated when dendritic cells are used as the antigen-presenting cells. Here, we demonstrate that dendritic cells pulsed with poorly replicating, heat- or ultraviolet-inactivated influenza virus, induce equally strong CD8+ cytolytic T lymphocyte responses. The cytotoxic T lymphocytes are generated in the apparent absence of CD4+ helper cells or exogenous cytokines. Active viral protein synthesis is not required to charge class I molecules on dendritic cells. When pulsed with inactivated virus, < 1% of dendritic cells express nonstructural protein 1, which is only synthesized in the infectious cycle. To be optimally effective, however, the inactivated virus must retain its fusogenic activity, and presumably access the cytoplasm of dendritic cells. The data indicate, therefore, that dendritic cells require only small amounts of viral protein to charge class I molecules, most likely via traditional class I processing pathways. These results reopen the potential use of inactivated virus preparations as immunogens for cytotoxic T lymphocyte responses.

Detection of cytoplasmic IL-1 beta in peripheral blood mononuclear cells from intensive care unit (ICU) patients

Cytokines including IL-1 beta have been implicated in the pathophysiology of sepsis and the systemic inflammatory response. It is believed that certain critically ill patients may be 'primed' with respect to cytokine production, and that subsequent 'triggers' may cause exaggerated cytokine production in these patients with exacerbation of their clinical condition; however, no means of identifying 'primed' patients has been described. The presence of cytoplasmic IL-1 beta within peripheral blood mononuclear cells (PBMC) from patients in the ICU was investigated as a means of identifying 'primed' patients, using fluorescent antibody labelling and flow cytometry. The study revealed that PBMC from ICU patients had a different staining pattern for IL-1 beta than those from healthy subjects, and that PBMC from certain ICU patients did indeed stain strongly for IL-1 beta; however, the presence of these strongly staining cells was not associated with clinical condition or outcome. It is concluded that whilst it might be possible to identify 'primed' patients in the ICU using this technique, this is of no clinical value as a predictor of clinical course.

Flow cytometric detection of anti-neutrophil cytoplasmic autoantibodies

An intracytoplasmic immunofluorescence staining technique which allows the detection and quantification of anti-neutrophil cytoplasmic autoantibodies (ANCA) by flow cytometry is described. A polymorph neutrophil population from human peripheral blood was used in this study as indicator cells. These were fixed and permeabilized by paraformaldehyde, Tween 20 and saponin, to allow ANCA in the patients sera to reach their intracellular antigen targets. The numbers of indicator cells remained unaltered by the permeabilization protocol and no cell aggregation or loss of intracellular antigenicity was observed. An excellent agreement (91% (207/228)) between ANCA detection by immunofluorescence microscopy (IF) and flow cytometry was noted. Compared with IF assay, the flow cytometric method has a sensitivity of 93% (42/45) and a specificity of 90% (165/183). Although not able to discriminate between P-ANCA or C-ANCA, this flow cytometric method has the advantage of providing an objective, reproducible and quantitative measure of ANCA, which makes it an ideal technique for screening of patients sera for ANCA reactivities.

The detection of intracytoplasmic interleukin-2 in Jurkat E6.1 and human peripheral blood mononuclear cells using direct conjugate, two-colour, immunofluorescent flow cytometry

The most commonly used approaches for the estimation of cytokine protein production involve the quantification of cytokines produced, and accumulated, in a complex body fluid or supernatant of cultured cells, by means of a bioassay or immunoassay, but these techniques do not permit an estimation of the frequency or phenotype of cytokine-producing cells. Traditional methods use immunohistochemical based techniques which can be difficult to perform and interpret, whereas flow cytometry has the advantage of objective assessment and standardisation and is less labour intensive. In this study we have established a rapid and sensitive technique for the simultaneous detection of intracellular IL-2 in conjunction with CD3. Polyclonal goat anti-IL-2 and control goat IgG were conjugated to FITC and then separated from free fluorochrome using column chromatography. PHA activated PBMC or Jurkat E6.1 cells were fixed in paraformaldehyde and permeabilised with saponin, followed by the addition of directly conjugated antibodies (FITC anti-IL-2 or PE anti-CD3) alone or in combination. Samples were then analysed using a flow cytometer and the percentage of dual labelled cells calculated. Several methods have been previously established for the detection of intracellular cytokines using flow cytometry and employing multiple layers of antibodies in the detection steps. By using direct conjugates the technique is less time consuming, requires fewer controls and can be used to examine cytokine production by identifiable cell phenotypes in a mixed cell population.