摘要:

AbstractMacrophage‐like defense cells (hemocytes) of the pond snailLymnaea stagnalisgenerate reactive oxygen intermediates (ROIs) upon contact with non‐self, following kinetics similar to those of ROI production by mammalian leukocytes during respiratory burst. In this study, several inhibitors of NADPH‐oxidase, the key enzyme of the respiratory burst in mammalian phagocytes, were tested for their effect on oxidative activities [as demonstrated by nitroblue tetrazolium (NBT) reduction and luminol‐dependent chemiluminescence (LDCL)] of phagocytosing snail hemocytes. In the presence of di‐ phenylenc iodonium, zymosan‐stimulated hemocytes ofL. stagnalisfailed to reduce NBT and showed a markedly reduced LDCL response. Also, compounds that prevent assembly of functional NADPH‐oxidase complexes in activated mammalian cells were effective; preincubation of hemocytes with 1,4‐naphthoquinone inhibited the LDCL response and NBT reduction upon phagocytic stimulation. Furthermore, coincubation but not preincubation with five different catechol‐like phenols inhibited oxidative activities of zymosan‐stimulated hemocytes. These results imply similarities in composition and regulation of the ROI‐generating mechanisms of both mammalian and snail defense cells. It is postulated that inL. stagnalishemocytes, (1) NADPH‐oxidase activity is responsible for ROI production, (2) an active NADPH‐oxidase enzyme complex has to be assembled from putative cytosolic and membrane‐associated components, and (3) continuous replacement of active NADPH‐oxidase enzyme complexes is necessary to sustain respiratory burst‐like oxidative activities during interactions with non‐self.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.379

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractA cell‐by‐cell analysis of the secretory ability of stimulated, individual alveolar macrophages (AMs) was performed through use of a tumor necrosis factor a (TNF‐α) reverse hemolytic plaque assay. Two functional end points were measured: the percentage of AMs that were TNF‐α secretors and the cumulative amount of TNF‐α secreted by AMs (average plaque area, μm2). Lipopolysaccharide (LPS; 100 μg/ml) increased cumulative TNF‐α release at both 7 and 20 h of incubation. On the other hand, a phorbol ester (phorbol myristate acetate, PMA) stimulated TNF‐α release at 20 h of incubation but not at 7 h. Under nonstimulated culture conditions, 5‐10% of all AMs released detectable TNF‐α. PMA (but not LPS) induced a significant increase in the fraction of AMs capable of releasing TNF‐α (15.1 ± 1.1% vs. 9.0 ± 1.6%, PMA vs. control, P<.05). Differences in the time course of secreted TNF‐α, together with the recruiting effect of PMA, suggest that LPS and PMA target TNF‐α‐ secretory subpopulations of AMs that differ in number and secretory characteristics.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.384

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractInhibition of arachidonate release down‐ regulates immunoglobulin G‐mediated phagocytosis. This arachidonate requirement is selective for IgG‐ opsonized targets, suggesting that arachidonate may act as a second messenger for Fcγ receptor‐mediated phagocytosis. Here we report the characterization of a phospholipase, activated during phagocytosis, that releases arachidonate from phosphatidylethanolamine in the absence of intracellular calcium ([Ca]i≤ 2 nM). In vitro, a phospholipase with these characteristics was detected in soluble and particulate fractions of human monocyte homogenates. (E)‐6‐(Bromomethylene)tetrahydro‐3‐(l‐ naphthalenyl)‐2H‐pyran‐2‐one, a drug that selectively inhibits Ca‐independent phospholipase A2S, is shown to inhibit IgG‐mediated phagocytosis and its associated arachidonate release in intact monocytes as well as the in vitro enzyme activity. These findings provide a link between the whole‐cell and in vitro data and present the initial characterization of a receptor‐activated, calcium‐ independent phospholipase from human monocytes.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.389

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractHuman activated T cells adhere to synovial fibroblast‐like cells in vitro. The present study was conducted to investigate the consequences of T cell‐synovial fibroblast interactions with regard to induction of adhesion molecules and proinflammatory cytokines. A sensitive Western blot technique, polymerase chain reaction (PCR) amplification, and fluorescence‐activated cell sorter (FACS) analysis were used to analyze the induction of VCAM‐1 and ICAM‐1 expression in T cell‐synovial fibroblast cocultures. VCAM‐1 and ICAM‐1 expression could be induced in synovial fibroblast‐like cells by 2 h. PCR amplification showed that both forms of VCAM‐1 mRNA are found after the interaction of synovial fibroblasts with T cells. Up‐ regulation of VCAM‐1 and ICAM‐1 was confined to synovial fibroblasts; T cells did not express VCAM‐1 or increased ICAM‐1. In contrast to the T cell‐synoviocyte interaction, the interaction between T cells and dermal fibroblasts resulted in the up‐regulation of ICAM‐1 but not VCAM‐1, suggesting tissue‐specific regulation of VCAM‐1. The T cell‐synovial fibroblast interaction also resulted in increased levels of tumor necrosis factor (TNF), interferon‐ 7, and interleukin‐6 in coculture supernatant. Of the neutralizing antibodies used against these cytokines, only anti‐ TNF could significantly inhibit VCAM‐1 and ICAM‐1 expression. When T cells were separated from synoviocytes by a chamber that allowed medium exchange but no cell contact, VCAM‐1 and ICAM‐1 failed to be up‐regulated and cytokine accumulation in cocultures was drastically reduced. Our results demonstrate mutual cell activation of T cells and synoviocytes upon cell contact as shown by the release of T cell‐ and synoviocyte‐specific cytokines and suggest a cell contact‐mediated and T cell‐initiated mechanism for the chronic accumulation and retention of mononuclear cells via VCAM‐l/ICAM‐1 by synovial fibroblasts in the rheumatoid synovium.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.399

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractResident adherent peritoneal cells selectively released high amounts of interleukin‐1 (IL‐1) activity when treated with silica. The use of anti‐IL‐1 antisera showed that both IL‐Ια and IL‐1β were present in supernatants of silica‐treated macrophages. In contrast, intracellular IL‐1 activity was totally neutralized by anti‐ IL‐Ια antibodies and was easily converted into the mature IL‐Ια form by autolysis in cytoplasmic extracts. Anion exchange chromatography clearly separated the two IL‐1 species present in supernatants of silica‐ stimulated macrophages. Natural IL‐1β was further characterized by chromatofocalization; it had an apparent isoelectric point, pI, in the range 8.3‐8.6. In agreement with previous findings showing that IL‐1/3 was released only by apoptotic cells, we have found that silica‐treated macrophages underwent apoptosis. This was demonstrated by the characteristic laddering electrophoretic pattern of DNA extracted from silica‐treated cells and by the morphology of macrophage nuclei stained with the DNA‐specific dye DAPI. In addition, quantification of apoptotic cells was performed by a flow cytometric analysis based on the reduction of cellular DNA content exhibited by apoptotic cells. Treatment of macrophages with silica, therefore, results in an active process that promotes the processing and liberation of IL‐1β.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.407

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractWe present a description and analysis of a mouse model for pulmonary interstitial fibrosis that is induced by a specific immune response to a small reactive chemical group called trinitrophenyl. We describe the model, and then we examine the cellular mechanism for the induction of the fibrosis. The specific increase in hydroxyproline reached a peak by day 7 and persisted through day 28 in all animals that were sensitized to and challenged with the hapten. Distinct patterns of fibrosis that were seen histologically correlated with antigenic pretreatment and were dependent on T lymphocytes. We also report that the inflammatory and fibrotic responses could be adoptively transferred with immune lymphocytes but not with immune serum. In vivo administration of anti‐CD4 and anti‐CD8 monoclonal antibodies to sensitized mice prevented the development of immune‐ mediated lung inflammation and was effective in reducing hydroxyproline deposition. We conclude that (activated) T lymphocytes contribute to the pathogenesis of pulmonary fibrotic diseases. The possibility arises that haptens in the environment may promote sensitization of individuals via their skin or lungs and cell‐mediated immune responses to haptenated antigens within the lung may promote pulmonary fibrosis.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.414

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractWe have examined the effects of transforming growth factor β1 (TGF‐β1) on the regulation of murine bone marrow‐derived macrophage function. TGF‐β, added simultaneously with or up to 4 h before interferon‐γ (IFN‐γ) plus lipopolysaccharide (LPS), inhibited macrophage leishmanicidal activity, nitrite (NO2”) production, and secretion of prostaglandin E2. In contrast, no effect of TGF‐β could be demonstrated on macrophages stimulated with IFN‐γ plus tumor necrosis factor‐γ (TNF‐γ) under the same conditions. These results suggested that TGF‐β inhibited LPS‐induced triggering of macrophage activation, which was confirmed by studies with IFN‐ γ‐primed cells. Interestingly, when macrophages were pretreated with TGF‐β for 24 h, NO2−production in response to IFN‐γ plus TNF‐α was also inhibited. Although control and IFN‐γ/LPS‐stimulated macrophages were found to secrete latent TGF‐β, only the IFN‐ γ/LPS cultures produced biologically active TGF‐β. Significantly, active TGF‐β was present at concentrations shown earlier to inhibit macrophage function.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.423

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractUnder physiological conditions, T cell activation by major histocompatibility complex (MHC)‐anti‐ gen complexes requires engagement of both the T cell receptor (TcR) and the CD4 (or GD8) accessory molecules. It has been shown, however, that ligation of CD4 and GD8 can also inhibit T cell activation in an MHG‐independent way. Therefore, the role of CD4 in T cell activation and the mechanism of the suppression of T cell functions by anti‐CD4 are as yet unclear. We activated T cells by CD4/CD3 co‐cross‐linking and studied the effect of preincubation with anti‐CD4 on this activation. We show here that anti‐GD4 affects T cell activation in a complex, time‐dependent manner. Whereas short preincubations with anti‐GD4 usually enhanced T cell proliferation in response to subsequent co‐cross‐linking of CDS with GD4, longer preincubations led to its decrease. The observed suppression of proliferation after a long preincubation with anti‐CD4 was apparently due to impairment of TcR signaling, as assessed by measurement of Ca2+mobilization and tyrosine phosphorylation in T cells. These results add a temporal element to the previously observed synergism between the TcR and CD4 in T cell activation.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.430

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractA novel system for priming adult rabbit alveolar macrophages (AMs) in vivo for markedly enhanced oxidative responses is described. When adult rabbits were injected intravenously (i.v.) with 1‐ to 5‐μm particles such as zymosan, latex particles, or heat‐killed bacille Calmette‐Guérin, AMs were primed in 1‐3 days for greatly enhanced phorbol myristate acetate (PMA)‐ or opsonized zymosan (Op‐zym)‐elicited chemiluminescent (CL) responses. Intratracheal (i.t.) injection of zymosan particles also primed AMs for enhanced PMA‐ or Op‐ zym‐elicited CL responses. AMs obtained from particle‐ injected rabbits showed up to 100‐fold higher levels of PMA‐elicited CL responses than AMs from normal rabbits. In contrast, Op‐zym failed to prime normal AMs in vitro for enhanced CL responses. Whereas AMs could not be primed in vivo with an i.v. injection of particles of ‐ 24μmdiameter, AMs could be primed if the particles were administered by the i.t. route. The priming appears to be independent of particle types. The priming effect was of short duration and declined after 5 to 7 days. The possibility that this system represents the primitive cellular immune response found in invertebrates is discussed. The potential use of this system as a means of immune augmentation prompts further investigation.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.439

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractLipopolysaccharide (LPS) is one of the most potent stimuli for macrophages. The activities of LPS have been attributed to the lipid A region of the molecule. We have previously shown that pretreatment of macrophages with very low doses of LPS can selectively “reprogram” these cells to respond differentially to subsequent activation, as assessed by tumor necrosis factor‐α and nitric oxide (NO) production. Here we demonstrate that the relative capacity of various LPS preparations for induction of down‐regulation of subsequent LPS‐activated NO production correlates well with their relative potency for initiation of NO formation. Although LPS‐dependent activation can be regulated by a pertussis toxin (PT)‐sen‐ sitive factor, the LPS pretreatment‐induced reprogramming is shown here to be refractory to regulation by PT. These results suggest that, although the structural components of LPS dictating the relative activities of the molecule for activation versus reprogramming are similar, there may exist different pathways in initiation of LPS‐induced activation versus reprogramming.

ISSN:0741-5400    

DOI:10.1002/jlb.54.5.444

出版商:Wiley    

年代:1993

数据来源: WILEY