A flow cytometric and immunofluorescence microscopic study of tumor necrosis factor production and localization in human monocytes

Lead (Pb) Exposure Enhances Expression of Factors Associated with Inflammation

The human immune system is constantly exposed to xenobiotics and pathogens from the environment. Although the mechanisms underlying their influence have already been at least partially recognized, the effects of some factors, such as lead (Pb), still need to be clarified. The results of many studies indicate that Pb has a negative effect on the immune system, and in our review, we summarize the most recent evidence that Pb can promote inflammatory response. We also discuss possible molecular and biochemical mechanisms of its proinflammatory action, including the influence of Pb on cytokine metabolism (interleukins IL-2, IL-4, IL-8, IL-1b, IL-6), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNF-α); the activity and expression of enzymes involved in the inflammatory process (cyclooxygenases); and the effect on selected acute phase proteins: C-reactive protein (CRP), haptoglobin, and ceruloplasmin. We also discuss the influence of Pb on the immune system cells (T and B lymphocytes, macrophages, Langerhans cells) and the secretion of IgA, IgE, IgG, histamine, and endothelin.

FK506 and Cyclosporin A Enhance IL-6 Production in Monocytes: A single-Cell Assay

The effect of FK506 and cyclosporin A (CsA) on the production of interleukin 6 (IL-6) in adherent monocytes was studied at a single-cell level by the avidinbiotin- peroxidase complex methods. The percentage of IL-6-producing monocytes increased when stimulated with lipopolysaccharide (LPS) at concentrations between 10 ng/ml and 10 μg/ml, in a dose dependent manner. Both FK506 and CsA enhanced the percentage of IL-6- producing monocytes stimulated with 100 pg/ml-1 μg/ml of LPS up to values near those obtained with 10 μg/ml of LPS. The enhancement by FK506 and CsA was not seen when monocytes were stimulated with a high concentration of LPS (10 μg/ml). When monocytes were stimulated with a low concentration of LPS (10 ng/ml), FK506 and CsA enhanced IL-6 production in a dose dependent manner, at a drug concentration of 0.12 nM–1.2 μM (0.1–1 000 ng/ml) for FK506 and 0.83 nM–8.3 μM (1–10 000 ng/ml) for CsA. The optimal effect of FK506 was achieved at a concentration 7-fold lower than that of CsA. In contrast, production of turnout necrosis factor-α (TNFα and interleukin 1β (IL-1β) was slightly suppressed by FK506 and CsA at the concentrations tested. Moreover, pretreatment of monocytes with FK506 and CsA had a significant enhancing effect on LPS-induced IL-6 production, while treatment with FK506 or CsA after LPS stimulation had no effects on IL-6 production, suggesting that the enhancing effect of each drug is exerted before LPS stimulation or at an early stage of the post-receptor pathway after LPS stimulation. These experiments demonstrate that FK506 and CsA can selectively enhance IL-6 production in monocytes under certain conditions in vitro and, possibly, also in vivo.

How a cytokine is chaperoned through the secretory pathway by complexing with its own receptor: lessons from interleukin-15 (IL-15)/IL-15 receptor alpha

While it is well appreciated that receptors for secreted cytokines transmit ligand-induced signals, little is known about additional roles for cytokine receptor components in the control of ligand transport and secretion. Here, we show that interleukin-15 (IL-15) translocation into the endoplasmic reticulum occurs independently of the presence of IL-15 receptor alpha (IL-15R alpha). Subsequently, however, IL-15 is transported through the Golgi apparatus only in association with IL-15R alpha and then is secreted. This intracellular IL-15/IL-15R alpha complex already is formed in the endoplasmic reticulum and, thus, enables the further trafficking of complexed IL-15 through the secretory pathway. Just transfecting IL-15R alpha in cells, which transcribe but normally do not secrete IL-15, suffices to induce IL-15 secretion. Thus, we provide the first evidence of how a cytokine is chaperoned through the secretory pathway by complexing with its own high-affinity receptor and show that IL-15/IL-15R alpha offers an excellent model system for the further exploration of this novel mechanism for the control of cytokine secretion.

Immunological evaluation of the new stable ultrasound contrast agent LK565: a phase one clinical trial

Background

Ultrasound contrast agents (UCAs) allow the enhancement of vascular definition, thereby providing more diagnostic information. LK565 is a new second-generation UCA based on synthetic polymers of aspartic acid which is eliminated from the blood stream via phagocytosis. LK565 forms very stable air-filled microspheres and is capable of repeated passage through the pulmonary capillary bed after peripheral intravenous injection. This characteristic allows examination of the cardiac function or extracardiac vessel abnormalities up to 15 minutes.

Methods

A phase one clinical study was conducted on 15 healthy volunteers to identify the development of an undesirable immune response. Phagocytosis capacity, TNF-α secretion, and MHC class II upregulation of monocytes was monitored, as well as microsphere specific antibody development (IgM, IgG). Furthermore, the kinetics of the activation surface markers CD69, CD25, CD71, and CD11b on leukocytes were analyzed.

Results

Due to LK565-metabolism the administration of the UCA led to saturation of phagocytes which was reversible after 24 hrs. Compared to positive controls neither significant TNF-α elevation, neither MHC class II and activation surface markers upregulation, nor specific antibody development was detectable.

Conclusion

The administration of LK565 provides a comfortable duration of signal enhancement, esp. in echocardiography, without causing a major activation cascade or triggering an adaptive immune response. To minimize the risk of undesirable adverse events such as anaphylactoid reactions, immunological studies should be included in clinical trials for new UCAs. The use of LK565 as another new ultrasound contrast agent should be encouraged as a safe means to provide additional diagnostic information.

Defect of tumour necrosis factor-alpha (TNF-alpha) production and TNF-alpha-induced ICAM-1-expression in BRCA1 mutations carriers

BACKGROUND

Tumour necrosis factor-alpha (TNF-alpha) is a potent cytokine secreted primarily by activated cells from the monocyte/macrophage lineage which exhibits various antitumoral effects including the induction of apoptosis, necrosis, activation of lytic effector cells as well as upregulation of the expression of intercellular adhesion molecule-1 (ICAM-1) which is of decisive importance in the interaction with lymphokine activated killer cells. Previous studies from our laboratory have indicated impaired production of TNF-alpha by monocytes as well as decreased expression of ICAM-1 on monocytes derived from patients with various stages of breast cancer.

METHODS

In the present experiments, we have assessed spontaneous as well as lipopolysaccharide (LPS)-induced production of TNF-alpha by as well as expression of ICAM-1 on monocytes derived from healthy females with germline mutations of BRCA1 and from healthy age-matched control females.

RESULTS

We report that monocytes derived from healthy women with various germline mutations of BRCA1 had significantly decreased spontaneous (p = 0.03) and LPS-induced (p < 0.001) production of TNF-alpha, as compared to monocytes derived from healthy age-matched control females. In contrast, no difference in LPS- or TNF-alpha-induced production of interleukin-6 was found. Whereas unstimulated monocytes derived from healthy women with germline mutations of BRCA1 and from healthy control women had similar expression of ICAM-1, stimulation with cytokines TNF-alpha and/or interleukin-1 led to a significant increase of ICAM-1 expression on monocytes derived from control females only, but not from BRCA1 germline mutation carriers (p < 0.001).

CONCLUSION

We conclude that the presence of germline mutations of BRCA1 was associated with a selective deficiency in spontaneous and LPS-induced production of TNF-alpha and of TNF-alpha-induced ICAM-1 expression on peripheral blood monocytes.

Are macrophages involved in early myocardial reperfusion injury?

BACKGROUND

Neutrophils are the predominant phagocytes in the early stages of myocardial ischemia-reperfusion response and are also implicated in the development of tissue damage. This study examined the role of recruited macrophages in the evolution of this tissue injury.

METHODS

Farm pigs were subjected to 30 minutes of myocardial ischemia followed by 30 minutes of reperfusion. Biopsy samples were taken from the control, ischemic, and ischemic-reperfused left ventricle wall and processed for both morphologic and biochemical analyses. In situ production of tumor necrosis factor-alpha was evaluated by Western blot and immunofluorescence. A full hemodynamic evaluation was also performed.

RESULTS

Myocardial ischemia and early reperfusion caused marked neutrophil and macrophage tissue accumulation and tumor necrosis factor-alpha production by the injured tissue. Immunofluorescence studies allowed us to localize tumor necrosis factor-alpha predominantly in tissue-infiltrating macrophages. No depression in the global myocardial contractile function was observed, either during ischemia or after reperfusion.

CONCLUSIONS

These data suggest that the newly recruited macrophages within the ischemic and early post-ischemic myocardium may play a role in promoting neutrophil tissue infiltration and subsequent neutrophil-induced tissue dysfunction by producing tumor necrosis factor-alpha.

Detection of membrane-bound tumor necrosis factor (TNF): an analysis of TNF-specific reagents

Tumor necrosis factor (TNF) exists in two bioactive forms, the membrane integrated form and the proteolytically derived soluble cytokine. Both forms of TNF are involved in a variety of different physiological and pathophysiological situations. Here we analyzed different human and mouse TNF-specific reagents for their ability to determine the expression of membrane-expressed TNF. The data prove some antibodies to be very useful for the analysis of transmembrane TNF expression because these antibodies distinguish between the transmembrane form of TNF and soluble TNF bound to cellular TNF receptors. In addition, we found that recombinant human TNF receptor fusion proteins are advantageous tools to analyze both human and mouse transmembrane TNF expression.

Lipopolysaccharide induces expression of APO2 ligand/TRAIL in human monocytes and macrophages

Monocytes express cytotoxic factors of the tumour necrosis factor (TNF) ligand superfamily, including TNF and Fas ligand, both on the cell surface and in secreted form. In this report, we show that human monocytes and monocyte-derived macrophages stimulated with lipopolysaccharide (LPS) express APO2 ligand (APO2L, TRAIL), a recently discovered cytotoxic member of the TNF ligand superfamily. LPS increased the transcription of APO2L mRNA in monocytes and macrophages. Flow cytometric analysis showed low surface and high intracellular levels of APO2L, and LPS increased the expression of both. In addition, LPS increased the monocyte- and macrophage-mediated cytotoxicity against the APO2L-sensitive Jurkat and RPMI-8226 cells. Addition of the APO2L-binding decoy receptor 1 (DcR1)-Fc fusion protein inhibited the cytotoxicity by 30-70%. LPS also stimulated the release of soluble APO2L from the monocytes and macrophages. Monocytic phagocytosis of target cells was increased by LPS and partially inhibited by DcR1-Fc. Taken together, these data demonstrate a novel mechanism of cytotoxicity mediated by LPS-activated human monocytes and macrophages.

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.

Flow-cytometric assessment of in vivo cytokine-producing monocytes in HIV-infected patients

We have used two-color flow cytometry to study in vivo monocytic cytokine production at the single-cell level in HIV-infected patients. We demonstrated the presence of intracellular IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha in circulating CD14+ monocytes from HIV-infected patients. The specificity of intracellular staining with anti-cytokine antibodies was demonstrated by the suppression of the fluorescent signal when staining was performed in the presence of recombinant cytokines. We did not detect any specific intracellular staining when anti-IL-4 antibodies were used since monocytes do not produce IL-4. In vivo intracellular cytokine production of IL-1 alpha, IL-1 beta, IL-1ra, and TNF alpha was higher in monocytes from HIV-infected individuals compared to monocytes from healthy controls; however, only the data concerning IL-1 alpha reached statistical significance. Monocytic cytokines are involved in the regulation of HIV gene expression and may participate in the modulation of the Th1/Th2 balance. The ability to follow the production of a wide range of cytokines by circulating monocytes of HIV-infected patients should allow one to better analyze the role of monocytic cytokines in the pathogenesis of HIV disease.

Enhanced immunohistochemical detection of autonomic nerve fibers, cytokines and inducible nitric oxide synthase by light and fluorescent microscopy in rat spleen

We have developed enhanced immunohistochemical protocols for detecting autonomic nerve fibers and splenocyte-associated proteins in rat spleen. This includes norepinephrine-synthesizing enzymes (dopamine-beta hydroxylase (DBH) and tyrosine hydroxylase (TH)), neuropeptide Y (NPY), tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), c-fos protein, inducible nitric oxide synthase (iNOS), and the macrophage cell marker ED1. Animals were divided into sham-operated and splenic nerve-sectioned groups for detection of DBH, TH, and NPY. For immunodetection of TNF-alpha, iNOS, IFN-gamma and c-fos, animals were injected IV with saline or 100 microg of lipopolysaccharide (LPS) and were sacrificed at various time intervals post injection. Rats were perfused with 4% paraformaldehyde, spleens removed and cryoprotected, and 50-microm floating sections were cut on a freezing microtome. Immunodetection was performed with various detection systems and substrate/chromogen solutions, and in some cases using pretreatment with proteinase K (PK) for antigen unmasking. PK pretreatment increased immunostaining for DBH, TH, NPY, IFN-gamma, iNOS, and ED1, and the improvement was concentration-dependent. Using NPY immunostaining to index the signal-to-noise ratio for various substrates and detection systems, we found that an alkaline phosphatase detection system with NBT/BCIP as a substrate was the best procedure for light microscopy, whereas the CY3-labeled secondary antibody technique proved optimal for fluorescent microscopy. Surgical transection of the splenic nerve eliminated all nerve fiber staining for DBH, TH, and NPY. TNF-alpha, IFN-gamma, c-fos, and iNOS proteins were observed in the spleen in a time-dependent manner after LPS stimulation. Fluorescent double labeling, visualized with fluorescent confocal scanning laser microscopy, revealed many NPY fibers distributed among the ED1-labeled macrophages. These results demonstrate that immunohistochemistry can be used to index the activational effects of an immune challenge on splenocytes in situ and verifies that splenic immune cells are innervated by the sympathetic nervous system.

The transition of microglia to a ramified phenotype is associated with the formation of stable acetylated and detyrosinated microtubules

In situ and in vitro, microglia can have different morphologies, which are thought to reflect distinct physiological activities. Two extreme forms are ameboid and ramified microglia. To study cytoskeletal changes during differentiation, we used defined cell culture systems to yield cultures of ameboid or ramified microglia from mouse brain. With respect to proliferation, secretion, receptor-expression, and phagocytosis, ramified microglia was generally less active. We found that the transition to a ramified phenotype was accompanied by an increase in the relative amount of acetylated and detyrosinated tubulin. Whereas the modified microtubules were restricted to regions close to the microtubule-organizing centers (MTOCs) in ameboid cells, acetylated microtubules were abundant in ramified cells, where they appeared to traverse from one process to another with no apparent anchoring at MTOCs. The increase in acetylated and detyrosinated microtubules was paralleled by an increased stability against nocodazole-induced microtubule disassembly and by a lower rate of change in the length of the processes. Staining of retinal wholemounts confirmed the presence of acetylated microtubules in ramified microglia in situ. We conclude that during the transition of microglia to a ramified phenotype regulated processes exist, which cause a reorganization of microtubules and a change in composition of the microtubule skeleton resulting in a less dynamic and more stable microtubule network. Intracellular factors that are specifically involved in microtubule stabilization in ramified microglia need to be identified in future research and may provide a useful criterion for defining ramified microglia.

Pattern of cytokines and pharmacomodulation in sepsis induced by cecal ligation and puncture compared with that induced by endotoxin

The production of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 and their pharmacomodulation were evaluated in a model of polymicrobial sepsis induced in mice by cecal ligation and puncture (CLP) and were compared with the effects of endotoxin (lipopolysaccharide [LPS]) treatment. LPS levels rose as early as 1 h after CLP and increased further after 2 and 21 h. TNF-alpha was detectable in serum, spleen, liver, and lungs during the first 4 h, with a peak 2 h after CLP. IL-1 beta was measurable in serum after 24 h, and levels increased significantly in spleen and liver 4 and 8 h after CLP. IL-6 levels increased significantly in serum throughout the first 16 h after CLP. These cytokines were detectable after LPS injection, with kinetics similar to those after CLP but at a significantly higher level. To cast more light on the differences between these two animal models of septic shock, we studied the effects of different reference drugs. Pretreatment with dexamethasone (DEX); ibuprofen (IBU), an inhibitor of cyclooxygenase; and NG-nitro-L-arginine, an inhibitor of nitric oxide synthase, significantly reduced survival, while chlorpromazine (CPZ) and TNF did not affect it. Only the antibiotics and pentoxifylline significantly increased survival in mice with CLP. However, CPZ and DEX protected the mice from LPS mortality. On inhibiting TNF-alpha with DEX, CPZ, or pentoxifylline, survival was reduced, unchanged, and increased, respectively, and on increasing TNF-alpha with IBU and TNF, survival was decreased or unchanged, respectively, suggesting that the modulation of this cytokine does not play a significant role in sepsis induced by CLP, unlike treatment with LPS. The negative effects of IBU and N(G)-nitro-L-arginine suggest a protective role by prostaglandins and nitric oxide in sepsis induced by CLP.

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.

Semi-synthesis of polymyxin-B conjugated ovalbumin: evaluation of lipopolysaccharide binding avidity and neutralization of induced tnf-alpha synthesis

A method is described in these investigations for the semi-synthetic production of polymyxin-B conjugated ovalbumin in the form of polymyxin-B.Sulfo-SMCC.ovalbumin (PSO). The heterobifunctional "cross-linking" agent, Sulfo-SMCC was first reacted with polymyxin-B to produce a relatively pure reactive intermediate in the form of polymyxin-B.Sulfo-SMCC. Highly purified ovalbumin was then combined with the polymyxin-B.Sulfo-SMCC reactive intermediate and contaminants removed from the final PSO end product by exhaustive microdialysis. Purity of PSO was established with by high-performance cellulose acetate electrophoresis (HPCAE), and high-performance thin layer chromatography (HPTLC) analyses. Verification of polymyxin-B.Sulfo-SMCC.ovalbumin binding avidity for lipopolysaccharide (LPS) was determined by DotBLot analysis applying fluorescein isothiocyanate labeled E. coli (055:B5) LPS fractions (FITC-LPS). Efficacy of PSO to inhibit in vitro LPS-induced synthesis of tumor necrosis factor-alpha (TNF-alpha) was assessed with a tissue culture based biological assay system. In this context, semi-synthetic conjugates of PSO (0.349 microgram/ml) effectively inhibited Salmonella minnesota (RS) LPS (2.5 ng/ml well) induced TNF-alpha synthesis and corresponding cytoprotection (100%) to WEHI 164 clone 13 cell populations.

Platelet activating factor synthesis and metabolism in intestinal ischaemia-reperfusion injury

The object of this study was to characterize the synthesis and metabolism of platelet activating factor (PAF) by intestinal mucosa subjected to ischaemia–reperfusion injury. Canine intestinal mucosa produced 16:0-PAF, 18:0-PAF, and high levels of the corresponding lyso- PAF metabolites. Three h of intestinal ischaemia and ischaemia followed by 1 h of reperfusion did not affect the synthesis or metabolism of PAF by intestinal mucosa. Intestinal mucosa elaborated a factor that rapidly hydrolyzes PAF to lyso-PAF. The observed hydrolysis rate was not altered by ischaemia or ischaemia and reperfusion. In conclusion, this study suggests that intestinal mucosa produces PAF and rapidly hydrolyzes PAF. The PAF synthesis and metabolism rates of intestinal mucosa is not altered by ischaemia reperfusion in this model under the imposed conditions.

Whole blood method for simultaneous detection of surface and cytoplasmic antigens by flow cytometry

Dual parameter analysis of surface antigens in flow cytometry has become a standard method for detection of cell subsets. However, few methods have been described for the extension of multiparameter analyses to include cytoplasmic or intracellular antigens. Here we describe a simple and reproducible method for simultaneous detection of surface and intracellular antigens by flow cytometry in lysed whole blood samples. This method employs the use of digitonin, a mild glycoside detergent, and formaldehyde for permeabilization and fixation. Red blood cells are lysed with 2% acetic acid. Preparation of samples in this manner resulted in altered light scatter characteristics relative to unpermeabilized samples; however, gating issues were overcome using a combination of scatter vs. fluorescence gating. Quantitation of CD3+/CD4+ and CD3+/CD8+ cells using this method was equivalent to counts obtained with the reference method using a commercially available lysis procedure and fluorescence vs. scatter gating. The effectiveness of the permeabilization process was assessed using a monoclonal antibody designated TIA-1, which is specific for a cytoplasmic antigen associated with cytotoxic granules predominantly found in CD8+ cells. The method effectively quantitated TIA-1 positive cells and demonstrated the specificity of the reagent for a subpopulation of CD8+ lymphocytes. Using this simplified procedure for simultaneous identification of surface and cytoplasmic antigens could help in studies of cell activation, proliferation, and other functional characteristics of the immune system.

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

Two colour flow cytometry was used to analyse in situ cytokine expression by human monocytes. Whole blood was cultured in siliconised glass bottles, with or without E. coli lipopolysaccharide (LPS), for various times, and the mononuclear cells (MNCs) then exposed to a variety of permeabilisation procedures prior to flow cytometric analysis. Paraformaldehyde (PF)/saponin fixation preserved cellular morphology, and caused a reproducible degree of permeabilisation (estimated by propidium iodide inclusion: mean 94%, range 86-99% (n = 33)). After fixation with 4% PF and permeabilisation with 1% saponin at 0 degrees C in PBS containing 20% human serum, MNCs were incubated with phycoerythrin(PE)-conjugated mouse anti-CD14 (monocyte phenotype) and polyclonal rabbit anti-human interleukin-1 alpha (IL-1 alpha), IL-1 beta, tumour necrosis factor alpha (TNF-alpha), or control rabbit IgG. Binding of rabbit antibodies was detected using goat anti-rabbit IgG fluorescein isothiocyanate (FITC). FITC fluorescence was increased in CD14 PE positive cells with the three anti-cytokine antibodies following LPS stimulation, compared with controls. There was a reproducible dose related response in monocyte IL-1 beta and TNF-alpha expression following LPS stimulation, with early peaks in TNF-alpha (2 h), compared with IL-1 beta (4 h), and IL-1 alpha (12 h). Specificity of this cytokine detection system was confirmed by inhibition studies using the corresponding recombinant human cytokines, by an absence of staining in CD14 negative or unpermeabilised MNCs, and by the characteristic cytoplasmic localisation of the different cytokines visualised with UV immunochemistry. Hence, the methods described here provide a reproducible, semiquantitative and specific assay for the detection of cell associated monokines. The technique may be applicable to the analysis of a variety of different cytokines in other phenotypically defined cell populations.

TNF and IL-1 generation by human monocytes in response to biomaterials

The biocompatibility of surgically implanted materials may be compromised as a consequence of inflammatory reactions associated with phagocyte activation. Two important mediators of the inflammatory response are Interleukin-1 (IL-1) and tumor necrosis factor (TNF), both of which exert a wide range of biologic effects on many cells. This study was designed to evaluate the release of these cytokines by human monocytes (HM) brought into contact with four biomaterials utilized in clinical practice: polyurethane, expanded polytetrafluorethylene (ePTFE), Dacron velour, and woven Dacron. In vitro cultures for the generation of IL-1 and TNF by HM in the presence of the above biomaterials were established by exposing cells to each biomaterial in the presence and absence of lipopolysaccharide (LPS) with harvest of supernatants after 6 or 18 h. These studies showed that in the absence of LPS, IL-1 was released only by Dacron velour and woven Dacron associated monocytes while TNF was secreted in response to all of the materials. When LPS was present, however, monocytes associated with all of the materials released IL-1; and TNF release was greatly augmented. Further, the quantity of released cytokine was directly related to the duration of the association time. This study demonstrated that HM in association with various biomaterials were activated to produce both TNF and IL-1 and that the addition of nanogram quantities of LPS, such as would be produced if infection were present, greatly increased the amount of cytokines released.

Tumor necrosis factor in benign and malign tissue of the kidney

The use of tumor necrosis factor (TNF) in immunotherapy of tumor diseases has attracted increasing interest. Since the direct antitumor effect of the TNF is mediated by receptor-bound TNF, we immunohistologically stained both benign and malignant tissue from 35 tumor-bearing human kidneys for TNF. Using a polyclonal anti-TNF-antiserum, paraffin sections were tested in the presence and absence of in vitro preincubation with TNF. Furthermore, all specimens were stained immunohistologically for Tamm-Horsfall protein (THP) because this renospecific glycoprotein can bind TNF in a lectin-like manner. In the absence of TNF preincubation, malignant tissue was TNF-positive in 34 specimens, as was benign tissue from the same tumor-bearing kidneys in 35 cases. In several specimens the staining was so intense that preincubation with TNF did not enhance the reaction. Whereas TNF staining in tumor tissue was relatively homogenous, that in benign tissue was intensive in distal tubuli, moderate in proximal tubuli, and negative in glomeruli. THP staining was negative in malignant kidney tissue but positive in the distal tubuli of benign tissue, i.e., in the regions in which TNF staining was most intense. These results indicate that TNF binds not only to membrane, most likely in a receptor-mediated manner, but also to THP both in vivo and in vitro. In vivo binding of TNF to THP was confirmed in animal experiments in which pigs were given injections of TNF. Immunohistological staining of the animals' kidneys revealed positive reactions for both TNF and THP at the distal tubuli, indicating TNF binding to THP after in vivo TNF administration.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytolytic activities of activated macrophages versus paraformaldehyde-fixed macrophages; soluble versus membrane-associated TNF

Membrane-associated tumor necrosis factor (TNF) and soluble TNF were compared as to their lytic activities, and as to the kinetics of their expression by macrophages activated with LPS and/or IFN-gamma in the presence or absence of cycloheximide. EL 4 tumor cells, resistant and sensitive to lysis by recombinant TNF or membrane-associated TNF (paraformaldehyde (PF)-fixed activated macrophages) were used as targets. In the presence of cycloheximide the TNF-resistant S-EL4 cells were lysed by both TNFs. PF-fixed macrophages was cytolytic after 1 hr activation but not after 3 or more hours of activation. Their activity was totally inhibited by anti-TNF antibodies and was a composite of transmembrane (integral) TNF and soluble TNF conjugated to macrophage membrane TNF receptors. Treatment of the macrophages with glycine pH 3.0 buffer dissociated the conjugated TNF without affecting the integral membrane TNF. When macrophages were activated with LPS +/- IFN-gamma in the presence of cycloheximide or activated just with IFN-gamma their activity after fixation with paraformaldehyde was no longer detected. Nonfixed macrophages under these conditions still remained cytotoxic. Tumor cell susceptibility to membrane-associated TNF activity, in contrast to recombinant (soluble) TNF, was greatly reduced in the presence of nicotinamide, an inhibitor of ADP-ribosyltransferase, suggesting that the mechanisms of lysis by these TNFs may be different. The lytic activity of both TNFs was found to be receptor-dependent in that tumor cells, whose TNF binding sites were "down-regulated" by TPA, were rendered resistant to lysis by both membrane-associated and soluble TNFs.

Human astrocytes stimulate HIV-1 expression in a chronically infected promonocyte clone via interleukin-6

Human promonocyte cells chronically infected with human immunodeficiency virus type (HIV-1) (clone U1.1.5) were grown in the presence of media conditioned by human astrocytes and glioma cell lines U251 and 253. HIV-1 expression was assessed by measuring reverse transcriptase activity. All media conditioned by unstimulated and lipopolysaccharide (LPS) stimulated glial cells induced HIV-1 expression and contained detectable levels of interleukin-6 (IL-6) but not tumor necrosis factor-alpha (TNF-alpha). An antibody against IL-6, but not against TNF-alpha, reduced the induction of HIV-1 by the conditioned media in a concentration-dependent manner. The magnitude of HIV-1 induction by the conditioned media was proportional to the concentration of IL-6 in them. The data indicate that normal and transformed human astrocytes are capable of stimulating HIV-1 expression in chronically infected promonocytic cells by secreting IL-6. The results demonstrate that cytokines secreted by neural cells could play an important role in regulating HIV-1 expression in the brain.

Interaction between dactinomycin and tumor necrosis factor in mesothelioma. Cachexia without oncolysis

There is no effective therapy for human malignant mesothelioma, and its susceptibility to recombinant cytokines has not been studied extensively. Recombinant human tumor necrosis factor alpha (rHuTNF alpha) was evaluated for its in vitro and in vivo antitumor activity using a human malignant mesothelioma cell line [DeH128(m)], both in culture and heterotransplanted in nude mice. In vitro, rHuTNF alone had no direct antimesothelioma activity assessed using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide assay, but in combination with the transcription inhibitor, dactinomycin (AD), mesothelioma cell metabolic activity was inhibited (80% of control). The effects of this combination of agents were studied on DeH128(m) cells heterotransplanted as subcutaneous tumors in nude mice. In vivo there was no significant inhibition of tumor growth by combined rHuTNF alpha and AD therapy, but the combination produced marked cachexia in doses at which each component (rHuTNF alone or AD alone) was well tolerated. The authors conclude that the well-described in vitro interaction between AD and rHuTNF also operates in vivo to produce cachexia and that the combination of these two agents is likely to have a low therapeutic index in malignant mesothelioma.

Improved permeabilization procedure for flow cytometric detection of internal antigens. Analysis of interleukin-2 production

A cell membrane permeabilizing treatment is described which involves the use of lysolecithin at low concentration in acidic acetate buffer and paraformaldehyde fixation. It preserved well-separated scatter cytograms of small and large lymphocytes. The accuracy of the immunochemical detection of internal antigens by flow cytofluorography was demonstrated by the linear relationship between the percentage of fluorescent cells detected and the proportion of intracellular antigen-containing cells in mixtures with antigen-negative cell lines. Cell cycle analysis by dual nuclear staining with propidium iodide and FITC-conjugated Ki-67 antibody recognising in vitro stimulated human T lymphocytes verified that the proliferating lymphocytes retained their increased light scatter properties after permeabilization. Enumeration of interleukin-2 (IL-2) producing cells by their cytoplasmic immunofluorescence showed that enlarged lymphocytes were the main IL-2 producing cells. This improved permeabilization procedure, by gating small and enlarged lymphocytes separately, makes it possible to determine by two color fluorescence the immunophenotype of activated T cells committed to interleukin production.

Capacity of tumor necrosis factor to augment lymphocyte-mediated tumor cell lysis of malignant mesothelioma

Recombinant human tumor necrosis factor (rHuTNF) was evaluated both for direct anti-tumor action against human malignant mesothelioma and for its capacity to augment the generation and lytic phases of lymphocyte-mediated cytotoxicity against this tumor. rHuTNF was directly toxic by MTT assay to one of two mesothelioma cell lines evaluated, but had no effect on susceptibility to subsequent lymphocyte-mediated lysis of either line. TNF alone was incapable of generating anti-mesothelioma lymphokine-activated killer cell (LAK) activity. Furthermore, it did not augment the degree or LAK activity produced by submaximal interleukin-2 (IL-2) concentrations nor did it augment lysis of mesothelioma cells by natural killer (NK) or LAK effector cells during the 4-hr 51chromium release cytolytic reaction. The studies also suggest that mesothelioma targets are less responsive to TNF plus submaximal IL-2 concentrations than the standard LAK sensitive target Daudi, raising the possibility that intermediate LAK sensitive tumors such as mesothelioma may require separate and specific evaluation in immunomodulation studies. This in vitro study indicates that use of low-dose rHuTNF and IL-2 is unlikely to be an effective substitute for high-dose IL-2 in generation and maintenance of LAK activity in adoptive immunotherapy for mesothelioma.

Tumor necrosis factor-alpha analyzed within individual macrophages by combined immunocytochemistry and computer-aided image analysis

Immunocytochemical staining procedures were combined with computer-aided image analysis to quantitate the relative intracellular production of tumor necrosis factor-alpha (TNF) within individual macrophages. Optimal conditions for time and methods for the activation of TNF production, fixation of cells for optimal immunocytochemical staining, and image analysis methods were determined. Thioglycolate elicited peritoneal macrophages were readily activated to significantly increased levels of intracellular TNF, as early as 1 hr after activation with lypopolysaccharide (LPS) + interferon-gamma: maximum intracellular TNF was evident after 2-3 hr. Both LPS and interferon-gamma was necessary to increase intracellular TNF. Normal alveolar macrophages also readily produced increased intracellular TNF, but normal peritoneal and splenic macrophages were poorly activated to TNF production. Acid stripping of receptor bound TNF allowed discrimination between intracellular TNF/integral membrane TNF, and TNF-receptor-bound TNF. Results stress the importance of studying these TNF forms early after activation. Applications for TNF quantitation by these means are discussed.