SEARCH · PubMed Health

Results for “Trinitrobenzenes”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources

PubMed1996

Hapten-induced model of murine inflammatory bowel disease: mucosa immune responses and protection by tolerance.

We report here a murine model for experimental chronic colitis where administration of trinitrobenzene sulfonic acid (TNBS) in 50% ethanol induced inflammation of large intestine in susceptible (C3H/HeJ and BALB/c) but not resistant (C57BL/6 and DBA/2) mouse strains. We queried whether mucosal trinitrophenyl (TNP)-specific B cell responses were induced in mice with TNBS-induced colitis, and if induction of tolerance to TNBS by oral administration of this hapten protected mice from development of colitis. Isotypes and subclasses of polyclonal and TNP-specific Ab-forming cells (AFC) were assessed in mucosal and peripheral lymphoid tissues of C3H/HeJ mice with TNBS-induced colitis. Increased numbers of IgA- and IgG-secreting cells were found in the inflamed colon lamina propria. Inflamed colonic tissue also contained high frequencies of IgG anti-TNP AFC (predominantly of IgG1, IgG2a, and IgG2b subclasses); however, anti-TNP responses in noninflamed mucosal tissues of mice with colitis exhibited dominant IgA and IgM with low IgG anti-TNP responses. CD4+ T cells stimulated with TNP-splenocytes produced more IFN-gamma and less IL-4, suggesting a Th1-type response. Oral administration of TNBS before induction of colitis markedly decreased mucosal anti-TNP responses and completely inhibited anti-TNP IgG2a and IgG2b responses. Control mice did not show inhibition of anti-TNP AFC responses or TNBS-induced colitis. Intracolonic sensitization of susceptible C3H/HeJ mice with TNBS induces a localized IgG anti-TNP B cell response in the inflamed tissue, whereas prior oral administration of TNBS results in unresponsiveness to this agent and protects mice from development of TNBS-induced colitis.

Administration, Oral↗

PubMed1999

A synthetic mimetic of CD4 is able to suppress disease in a rodent model of immune colitis.

CD4+ mucosal T cells mediate the intestinal inflammation in Crohn's disease and may serve as an important target for immune intervention. Here we assessed the therapeutic effect of a synthetic mimetic of CD4 designed to mimic both the sequence and conformation of the complementarity-determining region 3 of murine CD4 V1 domain (rD-mPGPtide) in a mouse colitis model using immunization with 2,4,6-trinitrobenzene sulfonic acid (TNB). i.v. administration of the rD-mPGPtide but not control scrambled peptide could suppress severe inflammation in the chronic colitis mouse model. After treatment with the rD-mPGPtide, a striking improvement of diarrhea and acute wasting disease was observed with decreased mortality. Serum anti-TNB antibody titers, CD45RBlowCD4+ T cells in the lamina propria and IFN-gamma mRNA expression in the mucosa were significantly decreased with the rD-mPGPtide treatment. Anti-CD4 antibody also suppressed disease by depletion of CD45RBhighCD4+ T cells in the colonic mucosa. The observation that the synthetically engineered analogue of murine CD4 inhibits inflammation in a rodent disease model by different mechanisms than anti-CD4 antibody suggests that a human version of this peptide has potential therapeutic utility in CD4+ mucosal T cell-mediated intestinal inflammation in Crohn's disease.

Animals↗

PubMed2000

Hapten-induced colitis associated with maintained Th1 and inflammatory responses in IFN-gamma receptor-deficient mice.

IFN-gamma is a potent pro-inflammatory cytokine thought to be involved in the pathogenesis of Crohn's disease. To further define the role of IFN-gamma in intestinal inflammation, we studied the effects of intra-colonic 2,4,6-trinitrobenzene sulfonic acid (TNBS) instillation in mice with a functionally inactivated IFN-gamma receptor 1 (IFN-gammaR1(- / -)). Our results indicate that IFN-gamma is not necessary for the induction of hapten-induced colitis: after TNBS administration both wild-type and IFN-gammaR1(- / -) mice lost body weight, and the histological features of TNBS-induced colitis were comparable. Colons of IFN-gammaR1(- / -) mice contained a greater number of cells, represented by macrophages and CD4(+) T cells; caudal lymph node cells produced more IFN-gamma and TNF-alpha upon stimulation in vitro. Moreover, IL-18 and IL-12 p40 RNA levels were comparably up-regulated after TNBS treatment in IFN-gammaR1(- / -) wild-type mice. These findings demonstrate that IFN-gamma is dispensable for the development of TNBS-induced colitis. Importantly, the production of Th1 cytokines (e. g. IFN-gamma and TNF-alpha) by caudal lymph node T lymphocytes was enhanced rather than decreased in IFNgammaR1(- / -) mice with no evidence for default Th2 development.

Animals↗

PubMedDate not supplied

Mutation analyses of a series of TNT-related compounds using the CHO-hprt assay.

Trinitrotoluene (TNT) and related compounds were tested for induction of mutation in the CHO-hprt mutation assay. The parent compound, TNT, was consistently found to be mutagenic at concentrations above 40 microg ml(-1), whether or not S9 activating enzymes were added. Five TNT metabolites gave statistically significant but small increases in mutation frequency over solvent controls: 4-amino-2,6 dinitrotoluene, 2,4',6,6'-tetranitro-2',4-azoxytoluene, 2,2',6,6'-tetranitro-4,4'-azoxytoluene, 2',4,6,6'-tetranitro-2,4'-azoxytoluene and triaminotoluene. Clear dose-response relationships could not be established for the mutagenic response of these compounds. They are considered as very weak mutagens in this mammalian test system. Five compounds did not produce statistically significant mutation frequencies at the levels tested: 2-amino-4,6-dinitrotoluene, 2,4-diamino-6-nitrotoluene, 1,3,5-trinitrobenzene, 2,6-diamino-4-nitrotoluene and 4,4',6,6'-tetranitro-2,2'-azoxytoluene. The results indicate that none of the TNT metabolites tested pose a significant mutational health risk, at least as judged by the CHO-hprt assay.

Animals↗

PubMed2001

Electrochemical oxidation of sigma-complex-type intermediates in aromatic nucleophilic substitutions.

A series of sigma-adducts (1H-...7H-) derived from the addition of 2-nitropropenide ion to various nitrobenzofuroxans and nitrobenzofurazans have been oxidized electrochemically. The results show that the rearomatization of the carbocyclic ring of these adducts as well as that of a few additional 4,6-dinitrobenzofuroxan adducts (8 H- a-c) is associated with much higher oxidation potentials than found for the same process in the dinitro- and trinitrobenzene series. Especially high Eo values are measured for the oxidation of the 2-nitropropenide 4,6-dinitro- and 4-nitro-6-trifluoromethylsulfonylbenzofuroxan adducts 1H- and 4H- in acetonitrile: E (1H-)= 1.15 V versus SCE; Eo(4H-)=1.33V versus SCE. These values fit well with the available evidence that the chemical oxidation of these adducts requires the use of very strong oxidizing agents to proceed efficiently. The mechanism for the oxidation process has been established. It is shown to involve transfer of two electrons and liberation of one proton per sigma-complex precursor with no evidence whatsoever for the intermediacy of radical anionic species.

Journal Article↗

PubMed2002

Contrasting roles of IL-12p40 and IL-12p35 in the development of hapten-induced colitis.

IL-12(p70), a heterodimer composed of two subunits (p35 and p40), is a key cytokine for Th1 mediated inflammatory responses. We dissected the role of IL-12 in the development of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis by studying mice deficient in IL-12p40, IL-12p35, or IL-12Rbeta1. TNBS-treated IL-12Rbeta1(-/-) and IL-12p35(-/-) mice developed only a mild disease associated with low level IL-18 expression in IL-12p35(-/-) mice. In contrast, IL-12p40(-/-) mice developed more severe colitis than wild-type mice associated with high level colonic IL-18 expression. Administration of IL-12p40 neutralizing mononuclear antibody dramatically increased pathology in IL-12p35(-/-) mice similar to disease scored in IL-12p40(-/-) mice. Numbers of IFN-gamma-producing cells infiltrating the lamina propria were comparably augmented in the different groups of IL-12-mutant and wild-type mice. These results demonstrate that IL-12p40, in contrast to IL-12p70, inhibits TNBS-induced colitis and IL-18 expression independent of IFN-gamma.

Animals↗

PubMed1985

Effects of microwave radiation (340 and 900 MHz) on different structural levels of erythrocyte membranes.

By use of fluorescence probes 1-anilinonaphthalene-8-sulfonic acid, 2-toluidinylnaphthalene-6-sulfonate, pyrene, perylene and chemical label phosphatidylethanolamine 2,4,6-trinitrobenzele sulfonic acid, the effect of microwave radiation on the erythrocyte membrane was studied. The studies with the fluorescence probes were carried out on erythrocyte ghosts and with 2,4,6-trinitrobenzene sulfonic acid on whole erythrocytes. The fluorescence was measured during irradiation of the membranes with 340-MHz microwaves at an SAR of 100 W/kg. Trinitrophenylation of phosphatidylethanolamine from whole erythrocytes was performed simultaneously with microwave irradiation at 900 MHz (10 mW/cm2). It was shown that the microwave field decreased lipid viscosity, altered the structural state of lipid-protein contact regions, and decreased the protein shielding of lipids. These changes corresponded to those produced by thermal action of microwaves.

Animals↗

PubMed1989

Base and conformational specificity of an amine modification of DNA.

We have investigated the site and conformational preference of the reaction of a formaldehyde/amine reagent with DNA. Previous investigations of this laboratory have established that this reagent will react with native DNA, placing a positively charged amine moiety on the duplex that will survive exhaustive dialysis. The resulting adduct is duplex and base stacked in character, possessing B backbone geometry with a higher average winding angle and exhibiting remarkable stability with respect to the A-form, Z-form, or the single-strand denaturated species. In this current investigation, we have found that the stability of the adduct is dramatically reduced if the DNA is converted to mononucleotides, thus obviating the usual approach of nuclease digestion and chromatography for the identification of the modified nucleotides. Using indirect approaches, we have established that the reactive site that survives removal of the equilibrium concentrations of CH2O and amine is the exocyclic amino group of the guanine bases. This conclusion is based on (1) the positive correlation between GC content and the extent of adduct formation under standard reaction conditions (27 degrees C, 0.63M CH2O, 0.007M n-butylamine, pH 7); (2) decreases in the level of substitution of amine in DNA, which has this site blocked by trinitrobenzene modification; and (3) failure of poly(dI-dC) to retain amine upon dialysis. Raman spectra of the derivatized poly(dG-dC) show enhanced 2'-endo B character, with no marked shifts in the position of any of the lines, indicating the absence of any ring structures involving the N7 and the 06 of G. In standard reaction mixtures, other sites may react but this phenomenon appears to be minimal under conditions that do not favor fluctuational opening of base pairs. In the latter case, excess loading of amine on high GC content polymers produces a CD spectrum that is similar to one produced by poly(dA-dT) in the "X"-form [M. Vorlickova, E. Minyat, and J. Kypr (1984) Biopolymers 23, 1-4]. This conformation is lost, however, upon removal of excess reagents by dialysis and cannot be reestablished, in the absence of unbound amine and formaldehyde. The reaction is specific for the B-form of polynucleotides as demonstrated by the failure of poly(dG-m5dC) in the stable Z-form to exhibit substantial reaction. The B-form of this polymer will react readily with the retention of 0.23 moles amine/mole nucleotide under our standard reaction conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Amines↗

PubMed1988

The role of suppression in immunoregulation: in vivo analysis using a monoclonal antibody to T suppressor factors.

We have used a monoclonal antibody (mAb)-specific for murine T suppressor (Ts) cells (mAb 14-12) to study the role of T cells in tolerance and immunoregulation. We demonstrate that mAb 14-12 can block in vivo Ts cell activity in a variety of experimental systems. It prevents the induction of Ts cells induced by i.v. injection of the water-soluble hapten 2,4,6-trinitrobenzene sulfonic acid, and the protein antigen bovine serum albumin. When 14-12 mAb is given prior to the i.v. injection of trinitrophenyl-conjugated spleen cells (TNP-SC) it blocks the induction of Ts cells and sufficiently overcomes suppression so that TNP-SC is able to induce immunity. mAb 14-12 can convert nonresponder mice into responders for the Ir gene-controlled response to the random terpolymer L-glutamic acid60-L-alanine30-L-tyrosine 10 (GAT), and can substitute for cyclophosphamide in overcoming a suppressor barrier in the adoptive transfer of contact sensitivity. Administration of 14-12 mAb just prior to immunization results in the augmentation of contact sensitivity, antibody and plaque-forming cell responses. These results demonstrate the versatility of this reagent for the study of Ts cell activity.

Animals↗

PubMed1996

Tolerance towards resident intestinal flora in mice is abrogated in experimental colitis and restored by treatment with interleukin-10 or antibodies to interleukin-12.

There is now increasing evidence that hyperresponsiveness towards intestinal flora is a crucial event in the pathogenesis of inflammatory bowel disease (IBD). In support of this hypothesis, we recently described in humans that tolerance exists towards indigenous intestinal flora but is broken in active IBD lesions. In the present study, we have attempted to transfer this model into mice from different genetic backgrounds (BALB/c, SJL/J, C3H/HeJ). We found that mononuclear cells from spleen, small bowel and large bowel of mice do not proliferate, i.e. are tolerant when exposed to bacterial sonicates derived from autologous intestine (BsA) but do proliferate, i.e. are immune when exposed to bacterial sonicates derived from the heterologous intestine of syngenic littermates (BsH). Furthermore, we demonstrate that both local and systemic tolerance to BsA is broken in a murine model of chronic intestinal inflammation induced by the hapten reagent 2, 4, 6-trinitrobenzene sulfonic acid (TNBS), which mimics several important characteristics of Crohn's disease. Tolerance to BsA was restored and TNBS-induced colitis was abrogated in mice systemically treated with interleukin (IL)-10 or antibodies to IL-12. Treatment specifically restored tolerance to BsA, but did not suppress proliferation to BsH. In summary, we here report a new model for the study of immunity and tolerance towards bacterial products. Our data suggest that tolerance to BsA is an important protective mechanism and that restoration of tolerance intestinal flora by IL-10 and antibodies to IL-12 may be of potential therapeutic utility in patients with inflammatory bowel disease.

Animals↗

PubMed1997

Predominant pathogenic role of tumor necrosis factor in experimental colitis in mice.

Antibodies to tumor necrosis factor (TNF)-alpha have been recently proposed as effective treatment for patients with Crohn's disease. Here, we analyze the functional role of TNF-alpha in a mouse model of chronic intestinal inflammation induced by the hapten reagent 2,4,6,-trinitrobenzene sulfonic acid (TNBS) that mimics some characteristics of Crohn's disease in humans. Macrophage-enriched lamina propria (LP) mononuclear cells from mice with TNBS-induced colitis produced 10-30-fold higher levels of TNF-alpha mRNA and protein than cells from control mice. When mice with chronic colitis were treated by intraperitoneal injection of antibodies to TNF-alpha, an improvement of both the clinical and histopathologic signs of disease was found. Isolated macrophage-enriched LP cells from anti-TNF-alpha-treated mice produced strikingly less pro-inflammatory cytokines such as interleukin (IL)-1 and IL-6 in cell culture. The predominant role of TNF-alpha in the mouse TNBS-induced colitis model was further underlined by the finding that striking colonic inflammation and lethal pancolitis was induced in TNF-alpha-transgenic mice upon TNBS treatment. Conversely, no significant TNBS-induced colitis could be induced in mice in which the TNF-alpha gene had been inactivated by homologous recombination. Complementation of TNF-alpha function in TNF-/- mice by the expression of a mouse TNF-alpha transgene was sufficient to reverse this effect. Taken together, the data provide direct evidence for a predominant role of TNF-alpha in a mouse model of chronic intestinal inflammation and encourage further clinical trials with antibodies to TNF-alpha for the treatment of patients with Crohn's disease.

Animals↗

PubMed2003

CCR6 has a non-redundant role in the development of inflammatory bowel disease.

Antigen-loaded tissues such as the intestinal mucosa must simultaneously elicit appropriate immune response to innocuous bacteria and food proteins, and to potentially harmful antigens. Impairment of the mechanisms controlling this response may mediate the excessive immune reaction that can lead to tissue destruction and inflammatory intestinal diseases, including inflammatory bowel disease. The intestinal epithelium influences local immune responses through the expression of adhesion molecules, costimulatory factors, cytokines and chemokines. CCL20, a beta-chemokine expressed in epithelia from colon and other intestinal tissue, plays a role in immune responses of intestinal mucosa, as deduced from the defects in intestinal leukocyte homeostasis shown by mice lacking CCR6, the CCL20 receptor. We studied the response of CCR6-deficient mice in two models of inflammatory bowel disease. The data show that absence of CCR6 resulted in less severe intestinal pathology in animals treated with dextran sodium sulfate. Conversely, CCR6 deficiency alters leukocyte homeostasis and the cytokine environment in the intestinal mucosa; these changes are sufficient to confer susceptibility to trinitrobenzene sulfonic acid-induced intestinal inflammation in the otherwise resistant C57BL/6J mouse strain. These results suggest that the CCR6/CCL20 axis has a critical, non-redundant role in the in vivo control of immune responses in the intestine.

Animals↗

PubMed2004

Frontline: interferon regulatory factor-1 as a protective gene in intestinal inflammation: role of TCR gamma delta T cells and interleukin-18-binding protein.

The transcription factor IFN regulatory factor-1 (IRF-1) regulates production and activity of many inflammatory mediators and cells. Here, we investigated the role of IRF-1 in intestinal inflammation using clinical and histologic scores; inflammatory mediators were also measured in colonic tissue. Dextran sulfate sodium (DSS) or trinitrobenzene sulfonic acid (TNBS) was administered to wild-type (WT) or IRF-1 knockout (KO) mice. DSS or TNBS led to a dramatic increase in lethality and colitis severity in IRF-1 KO compared with WT mice. Reduced levels of IFN-gamma and IL-18-binding protein (IL-18BP) were observed in the colon of IRF-1 KO mice, whereas levels of inducible nitric oxide synthase, cyclooxygenase-2, phosphorylated STAT-3, chemokines, TNF-alpha, IL-1beta, IL-15, and IL-18 were not significantly changed. Intestinal inflammation was not altered in IFN-gamma KO mice or in WT mice given neutralizing anti-IFN-gamma antibodies, but was increased in mice lacking TCR gamma delta lymphocytes, a population significantly decreased in the intestine of IRF-1-deficient mice. Administration of IL-18BP reversed the increased susceptibility of IRF-1 KO mice to DSS. These results suggest a protective role for IRF-1 in intestinal inflammation, with a possible anti-inflammatory and/or restorative role. IL-18BP and TCR gamma delta cells appear to be critical factors in the anti-inflammatory effects of IRF-1.

Animals↗

PubMed2007

Remission-inducing effect of anti-TNF monoclonal antibody in TNBS colitis: mechanisms beyond neutralization?

BACKGROUND: Tumor necrosis factor (TNF) plays an important role in the pathogenesis of several inflammatory diseases. Its expression is increased in inflamed mucosa of Crohn's disease patients and anti-TNF treatment improves mucosal inflammation. Besides neutralization, induction of apoptosis of monocytes/macrophages and T cells is thought to be an important mechanism of action of the anti-TNF monoclonal antibody therapy. The aim was to investigate the pathogenic role of TNF in hapten-induced colitis models and to study the relationship between apoptosis induction and disease remission. METHODS: In 2 murine colitis models (trinitrobenzene sulphonic acid, TNBS, and oxazolone colitis), mice were injected daily with anti-TNF monoclonal antibody (mAb). Macrophages were collected from lamina propria of TNBS colitis mice. 7AAD and anti-active-caspase-3 staining were used to study DNA degradation and intracellular caspase activation. A pan-caspase inhibitor, N-benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone (Z-VAD-FMK), was given to a subgroup of the colitis mice. RESULTS: Treatment with anti-TNF effectively reduced intestinal mucosal inflammation in TNBS colitis but not in oxazolone colitis. Effectiveness was evidenced by a more rapid recovery of body weight and reduced cell infiltration, and downregulation of proinflammatory cytokines interferon-gamma (IFN-gamma), TNF, and IL-18 at the mRNA level. Apoptosis was induced in lamina propria macrophages after treatment with anti-TNF, and it was abrogated through short-term pretreatment with Z-VAD-FMK. CONCLUSION: Anti-TNF downregulates proinflammatory cytokines and decreases cell infiltration in the bowel after TNBS application. The remission-inducing effect of anti-TNF may partly rely on apoptosis induction.

Amino Acid Chloromethyl Ketones↗

PubMed2006

Predominant T helper type 2-inflammatory responses promote murine colon cancers.

Colon cancer is one of the most serious complications of inflammatory bowel diseases, especially ulcerative colitis (UC). Previous studies have shown that characteristic immunological event during inflammation in UC is the expression of T helper-type 2 (Th2) cell-derived cytokines. In this study, we investigated the influence of a predominant Th2-type cytokine response in colitis on carcinogen-induced colon tumors. Wild type (WT), interferon gamma (IFN-gamma) gene deficient (-/-) [Th2 dominant] or interleukin (IL)-4(-/-) [Th1-dominant] mice of BALB/c background were used in this study. To compare tumor formation, mice were given the carcinogen azoxymethane (AOM) and intrarectal administration of trinitrobenzene sulfonic acid (TNBS), to induce colitis. Thirty-three weeks after initial treatment, the total colon was examined. When IFN-gamma(-/-) mice were treated with AOM and TNBS, significantly higher number of tumors were seen (8.4 +/- 1.7) than in WT (3.3 +/- 2.9) or IL-4(-/-) (3.1 +/- 3.4) mice, which received identical treatments. A separate set of experiment, using less doses of AOM and TNBS also showed the higher frequency of tumor formation in IFN-gamma(-/-) mice than in IL-4(-/-) mice. Histologically, the tumors were well- or moderately-differentiated adenocarcinomas. No invasion into the submucosal or serosal layers of the intestine was seen. In immunohistological staining, some tumors in IFN-gamma(-/-) mice showed distinct nuclear expression of beta-catenin, in contrast to the strong membrane staining seen in tumors of IL-4(-/-) mice. In conclusion, colonic inflammation associated with Th2-dominant cytokine responses enhanced the formation of malignant neoplasms.

Adenocarcinoma↗

PubMed1991

Interaction of poly(sodium vinyl sulfonate) and its surface graft with antithrombin III.

Poly(sodium vinyl sulfonate) (PVS) was found to be 1/14 times as active as heparin in inducing the conformational change and activation of antithrombin III. The conformational change of antithrombin III was investigated in terms of the intrinsic fluorescence of tryptophan residue, the extrinsic fluorescence using 1,6-diphenyl-1,3,5-hexatriene as fluorescent probe, and Fourier-transform infrared spectroscopy. It was evident in the experiment using 2,4,6-trinitrobenzene sulfonate that PVS elicited the activity of antithrombin III by interacting with amino groups of the protein as does heparin. Sodium vinyl sulfonate was graft-polymerized onto polyetherurethane (PEU) film that was treated with glow discharge in advance. PVS-grafted PEU film adsorbed antithrombin III easily and, like ungrafted PVS, induced conformational change and activation of antithrombin III. However, the mechanism of interaction of the PVS graft with antithrombin III did not seem to be completely the same as that of ungrafted PVS in solution.

Antithrombin III↗

PubMed1983

Reassortment of cells according to position in mouse morulae.

Sixteen-cell mouse morulae were disaggregated and blastomeres originally occupying outer or inner positions were separated. Outer, inner, or unsorted populations of blastomeres were labeled with either trinitrobenzene sulphonic acid (TNP) or fluorescein isothiocyanate (FITC) and individual blastomeres aggregated to unlabelled partially decompact eight- to ten-cell morulae. After up to 6 h in culture, the positions of the labelled blastomeres within the aggregates were examined. The combined results demonstrated that between 86 and 92% of outer cells remained on the surface of the aggregate and flattened into extensive polygonal shapes, whereas 76-77% of the inner cells had become engulfed by the host morula cells and retained their initial spherical shape. Using unsorted cells, 33-37% were internalised, which is compatible with the most recent estimates of the presence of six to eight inner cells at the 16-cell stage. The possibility that differential adhesiveness of the outer and inner cells is involved in the allocation of cells to the trophectoderm and inner cell mass of the blastocyst is discussed.

Animals↗

PubMed1991

Plasma membrane appearance of phosphatidylethanolamine in stimulated macrophages.

Mouse peritoneal macrophages were labeled with [1-3H]ethanolamine, and the presence of radioactive [3H]phosphatidylethanolamine (PE) at the plasma membrane was monitored by reacting the cells with trinitrobenzene sulfonic acid (TNBS) under nonpenetrating conditions. Macrophages stimulated with either the calcium ionophore A23187 or zymosan demonstrated a larger proportion of radiolabeled PE in the plasma membrane than control, nonstimulated cells. In experiments in which macrophages were labeled with ethanolamine for increasing times, appearance of membrane 3[H]PE was stimulated as early as after 2 hr of labeling. Macrophages labeled for 24 hr, then stimulated and returned to fresh medium still reflected a higher amount of membrane 3[H]PE at 2 hr after the stimulation, suggesting stimulation results in long-term alterations in plasma membrane lipids. Protease-peptone-elicited macrophages, which are not stimulated by zymosan or ionophore, did not exhibit an increase in membrane 3[H]PE upon stimulation. The size of the TNBS-accessible radiolabeled PE pool increased proportionately with a second stimulation; however, a subsequent labeling of the cells with TNBS after brief warming increased the TNBS-accessible pool in control cells only. As shown in previous studies, macrophage stimulation resulted in an increased incorporation of lipid precursors into phospholipid. The mass of plasma membrane Tnp-PE relative to mass of PE was not increased in ionophore-treated macrophages in contrast to a small (approximately 22%) increase in zymosan-treated cells. These results are suggestive of alterations in lipid synthesis in stimulated macrophages and possible long-term changes in the structure and function of the plasma membrane of macrophages following stimulation.

Animals↗