摘要:

AbstractHuman milk neutrophils and macrophages were examined by flow cytometry to determine whether they displayed phenotypic markers of activation. The markers were CDllb and L‐selectin, which are increased or shed, respectively, from the surface of activated neutrophils. Phenotypic features of milk neutrophils and macrophages were similar to blood neutrophils stimulated with fMLP: plasma membrane expression of CDllb was increased and L‐selectin was decreased. After blood neutrophils were incubated in acellular milk, their expression of CDllb increased and L‐selectin decreased. The activation was not affected by trypsin but was significantly decreased by treating acellular milk with chloroform or ether. Sedimentation studies suggested that particulate fractions of milk were active. Further, the activation was partly blocked by treating target blood neutrophils with cytochalasin B. Thus, human milk neutrophils are activated, and the activation may be due partly to phagocytosis of membranous structures in milk.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.97

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractModifying the fatty acid composition of macrophages through diet can significantly alter some of their functions, such as tumoricidal capacity and tumor necrosis factor a (TNF‐α) production. The mechanism of that modification, however, is unknown. In this report, we provide evidence that fatty acids added to macrophages in culture can significantly alter macrophage TNF‐α production. For example when inflammatory macrophages were incubated with various doses of arachidonic acid [20:4(n‐6)] during activation with lipopolysaccharide (LPS), we observed a dose‐dependent decrease in the level of bioactive TNF‐α with complete inhibition at 2‐5 μΜ. This inhibition was specific for 20:4(n‐6) because in vitro treatment with other fatty acids, such as eicosapentaenoic [20:5(n‐3)]or docosahexaenoic [22:6(n‐3)] acids, had differential effects. The inhibitory action of 20:4(n‐6) did not involve toxicity because cell viability was not affected and in vitro interferon‐γ and lipopolysaccharide (LPS) activation of macrophages for killing of P815 tumor targets was not altered. Inhibition by 20:4(n‐6) occurred posttranscriptionally, and could be reversed when macrophages were treated with indomethacin during activation. Arachidonic acid treatment also significantly increased the production of immunoreactive prostaglandin E2(PGE2) by LPS‐treated and untreated macrophages. These results suggest that in vitro treatment of macrophages with 20:4(n‐6) may inhibit TNF‐α production through an alteration in the levels of PGE2at a posttranscriptional level. These results provide evidence that some dietary fats may affect macrophage activity through modification of eicosanoid synthesis.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.105

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractAnalysis by immunofluorescence‐activated cell sorting of human peritoneal macrophages from patients undergoing intermittent peritoneal dialysis revealed that they express the CD11/CD18 surface antigens, with CDllb and CD18 as the predominant ones. Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of im‐ munoprecipitates obtained from lysates of125I‐labeled macrophages with rabbit polyclonal antibodies against the CDlla‐c/CD18 complex or against CD18, revealed four radioactive bands corresponding to CDlla, CDllb, CDllc, and CD18. Monoclonal antibodies against CDllb and CD18 inhibited by 80 and 90%, respectively, the oxidative burst activation of the macrophages by type 1 fimbriatedEscherichia coli,whereas monoclonal antibodies against CDlla, CDllc, and CD43 were without effect. Our results suggest that CDllb and CD18 (receptors for C3bi) serve also as receptors for mannose‐specificE. colion human peritoneal macrophages and may be involved in the lectinophagocytosis of the bacteria by these cells.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.111

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractIn this report, we show that the pl4 subunit of calcium‐binding myeloid protein complex (p8,14) is phosphorylated in human neutrophils stimulated with either fMet‐Leu‐Phe, phorbol myristate acetate, or a calcium ionophore. Trifluoperazine, a calmodulin antagonist, caused hyperphosphorylation of pi 4 in intact resting neutrophils. Freincubation of resting cells with 10‐20 nM calyculin A, a potent protein phosphatase inhibitor, also caused enhanced labeling of pi 4, which was further progressively increased on stimulation with fMLP. Thus, the phosphorylation level of pi 4 in resting as well as in stimulated neutrophils appears to be controlled by an active protein phosphatase. The phosphorylation of pi 4 by a chemoattractant and by a phorbol ester is a novel finding supporting the current belief that p8,14 myeloid protein may play an important role in the metabolism of myeloid cells.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.114

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractTaurine is present in high concentrations in most mammalian tissues, including those that prodigiously produce oxidants. Taurine protects against bronchiolar damage induced by NO2, ozone, bleomycin, and amio‐ darone. Taurine is chlorinated to form taurine chloramine (Tau‐Cl) by the halide‐dependent myeloperoxidase system and, under physiological conditions, reduces HOC1 toxicity. Although NO and its metabolites, ΝO2−and NOs−, are thought to be major mediators of tissue damage resulting from oxidant exposure, cytokines, including tumor necrosis factor (TNF), are also involved. We examined the effects of Tau‐Cl on NO production and TNF release by using RAW 264.7 cells activated with recombinant interferon‐γ (rIFN‐γ; 50 U/ml) and lipopoly‐ saccharide (LPS; 10 μg/ml). NO was measured spec‐ trophotometrically as ΝO2−after reaction with Griess reagent and TNF was measured by FLISA. Tau‐Cl (0.5 mM) inhibits NO and TNF released into the medium by 47% and 43%, respectively. Tau‐Cl is actively transported into RAW 264.7 cells by an uptake system that is energy, temperature, and Na+dependent. Competition experiments demonstrate that the uptake system for Tau‐ Cl is distinct from that for taurine. In addition, the NO synthase activity of cytosolic preparations from activated RAW 264.7 cells is irreversibly inhibited by pretreatment with Tau‐Cl. We demonstrate that Tau‐Cl inhibits production of NO and TNF by activated macrophages and suggest a mechanism through which taurine supplementation may protect against oxidant‐induced tissue damage.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.119

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractRetinoids are pluripotent morphogens whose effects on gene expression are mediated through specific intracellular receptors. They have certain anti‐inflammatory effects in vivo, the basis of which is not clearly understood. To characterize mechanisms involved with potential anti‐inflammatory actions of retinoids, we studied the effects of retinoic acid (RA) on cytokine production in human peripheral blood monocytes. RA differentially modulated the expression of interleukin‐1β (IL‐10), IL‐6, and IL‐8 mRNAs depending on the inducing stimulus. While phorbol myristate acetate‐induced IL‐lβ and IL‐8 mRNA expression was increased by RA (IL‐6 could not be induced by this pathway in monocytes), IL‐lβ‐induced expression of IL‐1β and IL‐8 was markedly reduced and IL‐6 gene expression was almost completely suppressed. Lipopolysaccharide (LPS)‐induced cytokine synthesis was only slightly reduced and this required a longer preincubation (>72 h) of monocytes with RA. IL‐l‐induced de novo synthesis of IL‐6 protein and secretion of biologically active IL‐6 were also inhibited by RA. The inhibition pattern of RA was different from that of dexamethasone, which inhibited both IL‐1 and LPS effects. In summary, our data show that RA regulates monocyte cytokine expression selectively in response to the particular stimuli. Inhibition of IL‐lβ‐induced cytokine expression provides a mechanism that can explain some of the anti‐inflammatory effects of RA.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.125

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractAbstract: The effect of interleukin‐4 (IL‐4) on the proliferation and differentiation of myeloid leukemic cell ines was studied in vitro. A culture of murine myeloid cell line, Ml, with lipopolysaccharide (LPS) fromEscherichia coli,induced differentiation into macrophages that expressed Fc receptors and phagocytic ac‐ ivity. IL‐4 did not induce the differentiation of Ml cells put inhibited the differentiation of Ml cells induced with LPS. On the other hand, LPS arrested the proliferation of Ml cells. IL‐4 had no effect on the proliferation of Ml cells but restored the LPS‐induced arrest of the proliferation of Ml cells. IL‐1, IL‐6 and tumor necrosis factora(TNF‐α) also induced the differentiation of Ml cells into macrophages and arrested proliferation. IL‐4 suppressed the IL‐1‐, IL‐6‐, and TNF‐induced differentiation of Ml cells and restored the arrested proliferation with IL‐1, IL‐6, and TNF. Similar results were obtained with human myeloid cell line HL60. These results suggest that IL‐4 has a suppressive effect on the differentiation of myeloid cells into macrophages.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.133

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractPsoralens, together with ultraviolet light A (PUVA), are used for the treatment of several proliferative diseases. It has been suggested that the effectiveness of this treatment is due to induction of a specific immune response by PUVA‐treated lymphocytes that down‐ regulates untreated cells of the same specificity. The present studies show that the clinically used psoralen analogue 8‐methoxypsoralen (8‐MOP), as well as 4,8‐dimethyl‐ 5′‐(pyridiniummethyl)psoralen bromide (4NQ), a derivative that does not cross the cell membrane, when activated by UVA light, render lymphocytes unresponsive to mitogenic, antigenic, or phorbol myristate acetate + ionomy‐ cin‐induced stimulation. This state of unresponsiveness was not reversed by exogenous recombinant interleukin‐2. Treatment of lymphocytes with 4NQ and UVA light had no effect on the viability or the homing pattern of the cells to spleen or liver, whereas 8‐MOP induced toxicity in about 50% of cells after 3 days in culture. Using an adoptive transfer mouse model, we found that antigen‐ specific lymphocytes treated with PUVA (8‐MOP or 4NQ) had no effect on the ability of these mice to respond to a subsequent challenge with the same or an irrelevant antigen. This was tested by measuring the T cell proliferative responses of lymph node cells from mice primed with keyhole limpet hemocyanin (KLH) or fowl gamma globulin (FGG) before or after adoptive transfer of large numbers of KLH‐ or FGG‐specific PUVA‐treated lymph node cells. No effects of antigen‐primed PUVA‐treated cells on antigen‐primed untreated cells were observed in vitro in mixed lymphocyte cultures responding to the relevant antigen. These results suggest that, in our model system, PUVA induces cell inactivation but does not affect systemic T cell responses.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.138

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractThrombin has receptor mediated effects on a variety of cell types. A recently cloned platelet thrombin receptor exerts its effects by a tethered‐ligand mechanism. A similar receptor was shown in at least two nonplatelet cell types, fibroblasts and endothelial cells. Thrombin has biologically important effects on leukocytes, but the type of receptor mediating the effects is not known. Therefore, we examined the responses of monocytes, neutrophils, and lymphocytes to thrombin and to an agonist specific for the platelet‐type thrombin receptor. We compared the effects of a peptide (SFLLRNPNDKYEPF) corresponding to residues 42‐55 of the cloned platelet thrombin receptor on calcium flux in platelets and leukocytes. The thrombin receptor peptide induced increases in intracellular calcium in platelets and monocytes that reached a maximum at 5 μΜ peptide. The maximal increase was similar in magnitude to the response to thrombin. Lymphocytes showed a small and variable increase in intracellular calcium in response to thrombin or the thrombin receptor agonist. The thrombin receptor peptide had no effect on neutrophil calcium concentrations. When the amino acid corresponding to Arg 46 was replaced with Ala in the synthetic peptide, the ability to increase intracellular calcium was abolished for both platelets and monocytes. The peptide instead had thrombin antagonist activity. Thus, monocytes respond to thrombin receptor peptides similarly to platelets. We conclude that human monocytes possess a thrombin receptor similar to that present on platelets. Furthermore, the residue corresponding to Arg 46 of the thrombin receptor is critical for receptor agonist activity.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.145

出版商:Wiley    

年代:1993

数据来源: WILEY

摘要:

AbstractTumors down‐regulate T cell responses partly by increasing macrophage (mφ)production of the suppressive molecule prostaglandin E2(PGE2). Because tumor growth increases mφtumor necrosis factor a (TNF‐α) production and TNF‐α stimulates mφPGE2synthesis, we examined the contribution of TNF‐α to fibrosarcoma‐induced mφ‐mediated suppression of allo‐ reactive CD4+T cell proliferation. We showed that tumorbearing host (TBH) mφsexpress high levels of TNF‐α mRNA, which leads to increased lipopolysaccharide‐ induced TNF‐α production. Timor cells were directly involved in mφTNF‐α synthesis because fibrosarcoma cells induced normal host (NH) mφs to produce TNF‐α. Addition of TBH mφs to allogeneic mixed lymphocyte reaction (MLR) cultures suppressed CD4+T cell proliferation more than NH mφs. The neutralization of endogenous TNF‐α activity with anti‐TNF‐α antibody (Ab) treatment reversed TBH, but not NH, mφ‐mediated suppression. Conversely, exogenous TNF‐α increased NH or TBH mφ‐mediated suppression but stimulated T cell proliferation without mφs. Kinetic treatment of MLR cultures with anti‐TNF‐α Ab or TNF‐α showed that TNF‐ αproduction and activity occurred at the beginning of T cell proliferation. When arachidonic acid metabolite synthesis was inhibited, TNF‐α‐induced suppression was blocked in NH mφ‐containing cultures and completely reversed in TBH mφ‐containing cultures. A PGErspecific enzyme‐linked immunosorbent assay showed that TNF‐a addition increased PGE2production in NH mφ ‐containing cultures to that of TBH mφ‐containing cultures. Exogenous PGE2did not affect the TNF‐α enhancement of T cell proliferation without mφs. Therefore, suppression induced by TNF‐α was caused by increased mφPGE2production and not by TNF‐α in concert with PGE2. Even though TNF‐a is known to enhance lymphocyte proliferation, we show that in the presence of mφs, the main TNF‐α producers, TNF‐α suppresses T cell proliferation. Perhaps increased TNF‐α production during pathological states, such as cancer, triggers the initial stages of suppression.

ISSN:0741-5400    

DOI:10.1002/jlb.54.2.152

出版商:Wiley    

年代:1993

数据来源: WILEY