bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulation of mannose receptor synthesis and turnover in mouse J774 macrophages
Authors: Fiani Maria L , Beitz Jill , Turvy Diane , Blum Janice S , Stahl Philip D
Published: January 2018

The mannose receptor, present on the plasma membrane of macrophages, promotes the internalization of glycoproteins and glycoconjugates via both endocytic and phagocytic pathways. The expression of this receptor is tightly modulated during monocyte/Mφ differentiation and cellular activation. We isolated clonal populations from murine J774 macrophage tumor cells, which differ in their surface expression of functional mannose receptors. To examine the potential mechanisms regulating receptor function in these cell lines, the interaction of receptor with ligand as well as receptor synthesis and degradation was analyzed. J774 clones with both high and low levels of mannose receptor activity were found to synthesize significant amounts of receptor protein, suggesting that the protein may be regulated at the level of synthesis and degradation. In J774 clones expressing very low receptor activity and protein, the half-life of mannose receptor molecules was substantially decreased. The evolution of multiple mechanisms modulating mannose receptor function may be critical in fine-tuning the role of this receptor in antigen processing and in scavenger and host defense functions. J. Leukoc. Biol. 64: 85–91; 1998.
Neutrophil degranulation and phospholipase D activation are enhanced if the Na+/H+ antiport is blocked
Authors: Gewirtz Andrew T , Seetoo Kurt F , Simons Elizabeth R
Published: January 2018

Neutrophils phagocytize high-valency immune complexes (HIC) by an Fc receptor-mediated mechanism. Engaging Fc receptors in this manner induces PMN to generate superoxide and release the contents of both their specific and azurophilic granules. Signaling events that precede and accompany PMN secretion include activation of phospholipase D (PLD), as well as changes in cytoplasmic [Ca2+] (δ[Ca2+]in) and pH (δpHin). Although the role of PLD and δ[Ca2+]in in mediating Fc receptor-mediated PMN secretion has been studied, whether pHin plays a regulatory role has not yet been defined. HIC-stimulated PMN undergo an intracellular acidification followed by a prolonged Na+/H+ antiport-mediated alkalinization. To investigate the role of the pH transient in controlling degranulation, the Na+/H+ antiport was inhibited either with 100 μM dimethylamiloride (DMA) or by substituting N-methyl-glucamine for extracellular sodium. Blocking the antiport with DMA led to hyper-acidified PMN, which exhibited an increase in degranulation, but did not affect generation of superoxide. DMA did not alter the ability of neutrophils to phagocytose and oxidize dichlorodihydrofluoresceinated HIC, suggesting the increase in degranulation was not the result of failed phagocytosis. Investigation into whether the observed increase in degranulation when the antiport was blocked was mediated by PLD or δ[Ca2+]in revealed that blocking the antiport increased HIC-induced PLD activity but had no effect on HIC-induced δ[Ca2+]in. Blocking the Na+/H+ antiport by ion substitution caused similar effects on PMN signaling and secretion as was seen with DMA. These results indicate that Na+/H+ antiport activity is not necessary for degranulation or superoxide release in HIC-stimulated PMN and that hyperacidification of the cytoplasm can modulate degranulation. Therefore, pHin, via its effect on PLD, may be a control point of degranulation and may represent one way that neutrophils achieve differential control of their antibacterial products. J. Leukoc. Biol. 64: 98–103; 1998.
Binding of the endogenously expressed Epstein-Barr virus (EBV) envelope glycoprotein gp350 with the viral receptor masks the major EBV-neutralizing epitope and affects gp350-specific ADCC
Authors: Khyatti Meriem , Ahmad Ali , Blagdon Marie , Frade Raymond , Menezes José
Published: January 2018

The major neutralizing epitope (MNE) for the Epstein-Barr virus (EBV) is present on its envelope glycoprotein gp350/220 (hereafter referred to as gp350) in close proximity to the virus-receptor (CR2) binding site and is recognized by the neutralizing murine monoclonal antibody (mAb) 72A1. We studied the reactivities of 72A1 and another anti-gp350 mAb 2L10 (which does not neutralize EBV) with gp350 expressed on three different lymphoid cell lines (Raji, CEM.NKr and BJA-B). Our results indicate that gp350 expressed on the surface of CR2-positive cells interacts with the viral receptor and that this interaction masks the major EBV-neutralizing epitope. The interaction was reversible and the masked epitope was revealed on incubation with an excess of anti-CR2 mAb OKB7. Gp350-expressing CEM-NKr cells with intact MNE exhibited significantly higher (P ≤ 0.05) lysis in gp350-specific antibody-dependent cellular cytotoxic assays compared with its Raji counterpart. The present results may have important implications for the use of soluble viral receptors as therapeutic agents in acute and chronic EBV and other viral infections (e.g., HIV-1). J. Leukoc. Biol. 64: 192–197; 1998.
Lipopolysaccharide induction of monocyte matrix metalloproteinases is regulated by the tyrosine phosphorylation of cytosolic phospholipase A2
Authors: Shankavaram Uma T , DeWitt David L , Wahl Larry M
Published: January 2018

Activation of human monocytes with lipopolysaccharide (LPS) results in the production of matrix metalloproteinases (MMPs) through a prostaglandin E2 (PGE2)-cAMP-dependent pathway. In this study, the early signaling events involved in this signal transduction pathway were evaluated. Pretreatment of human peripheral blood monocytes with herbimycin A, a tyrosine kinase inhibitor, or arachidonyl trifluoromethyl ketone (AACOCF3), a specific inhibitor of cytosolic phospholipase A2 (cPLA2) inhibited the induction of PGE2 by LPS. This resulted in the inhibition of protein expression of gelatinase B (MMP-9) and interstitial collagenase (MMP-1), two major MMPs secreted by activated monocytes. Addition of arachidonic acid (AA) reversed the inhibitory effect of herbimycin A or AACOCF3 on monocyte MMP production, indicating the importance of tyrosine phosphorylation and the involvement of cPLA2 at an early stage in the signal transduction pathway of MMPs. This finding was further supported by LPS-induced shift in cPLA2 migration and tyrosine phosphorylation based on immunoblotting and immunoprecipitation studies. These results provide evidence that tyrosine phosphorylation of cPLA2 is one of the initial steps needed for the LPS induced MMP production in human monocytes. J. Leukoc. Biol. 64: 221–227; 1998.
Endotoxin activation of mitogen-activated protein kinase in THP-1 cells; diminished activation following endotoxin desensitization
Authors: Durando Mary M , Meier Kathryn E , Cook James A
Published: January 2018

The signal transduction events occurring in monocytes in response to endotoxin (LPS) stimulation are incompletely delineated, although pertussis toxin (PT)-sensitive G proteins and the mitogen-activated protein kinase (MAPK) cascade have been implicated. Cellular desensitization in response to 18-h pre-exposure to 1 μg/mL LPS alters signal transduction pathways of cellular activation and decreases production of certain inflammatory mediators such as thromboxane (Tx)B2, the stable metabolite of TxA2. We hypothesized that LPS stimulation of the human monocyte cell line THP-1 occurs via MAPK activation, and that LPS desensitization, induced by pre-exposure to LPS, is associated with altered signaling through the MAPK cascade. Involvement of a specific MAPK, ERK, in LPS-stimulated TxB2 production was further tested using a specific MAPK cascade inhibitor, PD98059 (PD). PD inhibited LPS and phorbol myristate acetate (PMA)-stimulated ERK activation as demonstrated by immunoblots using anti-activated ERK antibodies. PD significantly inhibited LPS and PMA-stimulated TxB2 synthesis to non-detectable levels, suggesting an involvement of MAPK in LPS-stimulated activation. Because PT-sensitive G proteins mediate LPS-stimulated signal transduction, their role in MAPK activation was tested. Pretreatment with PT inhibited basal and LPS-stimulated, but not PMA-stimulated ERK activation. Activation of ERK after LPS desensitization was also assessed. LPS pre-exposure resulted in a profound decrease in LPS-stimulated activation of ERK, but did not affect PMA activation of ERK. These data implicate the involvement of the MAPK cascade in LPS-stimulated activation of THP-1 cells and suggest coupling of Gi proteins and MAPKs in LPS-stimulated events. LPS desensitization is associated with decreased MAPK activation, but does not impair MAPK activation by PMA. Thus, LPS desensitization appears to selectively alter signal transduction upstream of ERK. J. Leukoc. Biol. 64: 259–264; 1998.
Interferon-γ gene expression in cycling and pregnant mouse uterus: temporal aspects and cellular localization
Authors: Platt J Sue , Hunt Joan S
Published: January 2018

Interferon-γ (IFN-γ) is a potent proinflammatory cytokine that modulates hematopoietic cell maturation, differentiation, activation, and apoptosis. To evaluate the postulate that locally produced IFN-γ could influence uterine hematopoietic cells, specific protein was detected by immunohistochemistry and messenger RNA (mRNA) was identified by in situ hybridization in cycling and pregnant mouse uteri. In cycling uteri, IFN-γ was limited to luminal and glandular epithelial cells during the estrus phase of the cycle. In pregnant uteri, IFN-γ was prominent at early (gestation day 6–10) and late (gestation day 18) stages. IFN-γ-producing cells identified by in situ hybridization included uterine epithelial cells, natural killer cells, macrophages, placental trophoblast cells, and cells in the degenerating metrial gland. Collectively, the data indicate that programming of immune and other cells via autocrine and paracrine pathways could be achieved by locally produced IFN-γ, and suggest that uteroplacental IFN-γ may be most influential during early and late stages of pregnancy. J. Leukoc. Biol. 64: 393–400; 1998.
Nitric oxide synthase inhibition reduces muscle inflammation and necrosis in modified muscle use
Authors: Pizza Francis X , Hernandez Israel J , Tidball James G
Published: January 2018

The objective of this study was to determine the role of nitric oxide in muscle inflammation, fiber necrosis, and apoptosis of inflammatory cells in vivo. The effects of nitric oxide synthase (NOS) inhibition on the concentrations of neutrophils, ED1+ and ED2+ macrophages, apoptotic inflammatory cells, and necrotic muscle fibers in rats subjected to 10 days of hindlimb unloading and 2 days of reloading were determined. Administration of NOS inhibitor Nω-nitro-l-arginine methyl ester (l-NAME) significantly reduced the concentrations of neutrophils, ED1+ and ED2+ macrophages, and necrotic fibers in soleus muscle relative to water-treated controls. The concentration of apoptotic inflammatory cells was also significantly lower for l-NAME-treated animals compared with water-treated controls. However, the proportion of the inflammatory cell population that was apoptotic did not differ between l-NAME-treated and control animals, suggesting that l-NAME treatment did not decrease inflammatory cell populations by increasing the frequency of apoptosis. Thus, nitric oxide or one of its intermediates promotes muscle inflammation and fiber necrosis during modified muscle use and plays no more than a minor role in the resolution of muscle inflammation by inducing apoptosis of inflammatory cells. J. Leukoc. Biol. 64: 427–433; 1998.
Taurine blunts LPS-induced increases in intracellular calcium and TNF-α production by Kupffer cells
Authors: Seabra Vítor , Stachlewitz Robert F , Thurman Ronald G
Published: January 2018

Activation of Kupffer cells by lipopolysaccharide (LPS) plays a pivotal role in the onset of pathophysiological events that occur during endotoxemia and intracellular calcium ([Ca2+]i) is involved in LPS-stimulated cytokine production. Recently, it was shown that Kupffer cells contain a glycine-gated chloride channel. Because taurine, a ubiquitous sulfur-containing β-amino acid, acts similarly to glycine in neurons by causing hyperpolarization, it was hypothesized that taurine would act via a similar mechanism, blunting the LPS-induced increase in [Ca2+]i in Kupffer cells. To test this hypothesis, Kupffer cells were isolated from female Sprague-Dawley rats and cultured for 24 h. LPS-induced changes in [Ca2+]i were monitored fluorometrically in single cells, whereas levels of tumor necrosis factor α (TNF-α) released by Kupffer cells after exposure to LPS were measured by enzyme-linked immunosorbent assay. Taurine significantly blunted the LPS-induced increase in [Ca2+]i in a dose-dependent manner (IC50, 0.1 mM). This effect was reversed by strychnine (1 μM) and was prevented when chloride was removed from the extracellular media. Moreover, taurine increased 36Cl– uptake by Kupffer cells in a dose-dependent manner (EC50, 0.2 mM). Furthermore, strychnine (1 μM) reversed the effect of taurine on 36Cl– uptake. These results indicate that taurine activates a glycine-gated chloride channel in Kupffer cells causing chloride influx. In addition, LPS-induced TNF-α production was reduced by more than 40% by taurine, an effect that was also reversed by strychnine. In conclusion, taurine blocks the increase in [Ca2+]i due to LPS and significantly reduces TNF-α production by mechanisms involving chloride influx into the Kupffer cell. J. Leukoc. Biol. 64: 615–621; 1998.
Glucocorticoids protect against suppression of T cell responses in a murine model of acute ethanol exposure and thermal injury by regulating IL-6
Authors: Faunce Douglas E , Gregory Meredith S , Kovacs Elizabeth J
Published: January 2018

Previous reports by this laboratory demonstrated that acute alcohol exposure combined with a 15% body surface area dorsal scald injury results in significant reductions in delayed-type hypersensitivity (DTH) and splenocyte proliferative responses compared to either insult alone. Previous studies by this lab have also shown that these defects are mediated, in part, by increased production of interleukin-6 (IL-6). Because both alcohol exposure and thermal injury are known to modulate glucocorticoid (CORT) levels, and CORT regulates IL-6 gene expression, the relationship between circulating CORT and IL-6 production in burn + ethanol mice was examined . At 24 and 48 h post-burn, a positive correlation existed between circulating CORT levels and measurements of cellular immune function. Administration of exogenous CORT to burn + ethanol-treated mice resulted in significant restoration (to 60% of control) of DTH and splenocyte proliferative responses. This restoration was concomitant with a down-regulation of circulating and macrophage-derived IL-6. The specificity of CORT in modulating these responses was tested by assessing cellular immune function and IL-6 levels after glucocorticoid receptor blockade with RU486. Taken together, these data strongly suggest that under normal circumstances CORT protects burned mice from severe immune dysfunction, a protection that is not afforded to burn + ethanol-treated mice. Furthermore, the immune dysfunction observed in burn + ethanol mice may be due to a lack of glucocorticoid attenuation of IL-6. J. Leukoc. Biol. 64: 724–732; 1998.
Role of ICAM-1 and ICAM-2 and alternate CD11/CD18 ligands in neutrophil transendothelial migration
Authors: Issekutz Andrew C , Rowter Derek , Springe Timothy A
Published: January 2018

We evaluated the relative contribution of ICAM-1 and ICAM-2, known ligands on endothelium for LFA-1 and Mac-1, in spontaneous neutrophil (PMN) transendothelial migration (TEM) across IL-1-activated HUVEC monolayers or TEM induced by C5a or IL-8 across unstimulated HUVEC grown on polycarbonate filters. Adhesion blocking mAb to ICAM-1 [R6.5 F(ab)2] or ICAM-2 [CBR IC2/2 F(ab)2] tended to inhibit TEM under each condition but, in general, inhibition was significant only with both ICAM-1 and ICAM-2 blockade. mAb to LFA-1 partially inhibited migration to C5a or IL-8 across unstimulated HUVEC and inhibition was not altered by additional treatment of HUVEC with mAbs to ICAM-1 and -2. In contrast, with IL-1 HUVEC, mAb to ICAM-1 significantly inhibited this LFA-1-independent TEM. mAb to Mac-1 alone partially inhibited TEM and, when combined with mAb to LFA-1, migration was almost completely blocked with all TEM conditions tested. The contribution of alternate ligands for Mac-1 in mediating Mac-1-dependent but ICAM-1/-2-independent C5a-induced TEM was examined using anti-LFA-1-treated PMN and anti-ICAM-treated resting HUVEC. Addition of RGD peptides, fibronectin, fibrinogen, heparins, collagens alone or in combination, even to heparinase-treated HUVEC, did not inhibit this Mac-1-mediated PMN TEM. The results indicate that: (1) LFA-1 mediates PMN TEM primarily by interaction with ICAM-1 and ICAM-2; (2) ICAM-2 may function in concert with ICAM-1 in this role, especially on unstimulated endothelium, and (3) Mac-1 on PMN also plays a major role in TEM and can utilize yet to be identified ligands distinct from ICAM-1 or -2, especially on unstimulated endothelium. J. Leukoc. Biol. 65: 117–126; 1999.
Macrophage phagocytosis of wound neutrophils
Authors: Meszaros Adriana J , Reichner Jonathan S , Albina Jorge E
Published: January 2018

Resolution of acute inflammation is thought to require the recognition and phagocytosis of apoptotic neutrophils (PMN) through receptor-ligand interactions with macrophages (Mϕ). This hypothesis was tested in rat wounds by quantifying apoptosis in freshly harvested and aged-in-culture PMN taken from wounds 1–3 days after injury and by using these wound PMN as phagocytic targets for wound, immune-activated peritoneal, and resident peritoneal Mϕ. Less than 6% of freshly harvested PMN exhibited characteristics of apoptosis. On aging in culture, day 1 PMN did not undergo apoptosis, whereas 41 ± 1 and 29 ± 1% of day 2 and 3 PMN, respectively, developed apoptosis, which corresponded to increased ingestion by Mϕ. All three Mϕ populations engaged different receptor-ligand pairs for the recognition and phagocytosis of PMN. Results indicate the resistance of early wound PMN to age-induced apoptosis, demonstrate wound-Mϕ phagocytosis of wound PMN, and identify distinct receptor utilization by wound and other Mϕ to ingest wound PMN. J. Leukoc. Biol. 65:35–42; 1999.
Soluble vascular cell adhesion molecule (VCAM)-Fc fusion protein induces leukotriene C4 secretion in platelet-activating factor-stimulated eosinophils
Authors: Tsuruta Ryosuke , Cobb Ronald R , Mastrangelo Marian , Lazarides Elias , Cardarelli Pina M
Published: January 2018

Eosinophil adhesion to vascular cell adhesion molecule-1 (VCAM-1) is important for cellular recruitment into allergic inflammatory sites. To determine whether eosinophil adhesion to VCAM-1 affects cell function, leukotriene C4 (LTC4) was measured. Human eosinophils were incubated with platelet-activating factor (PAF) in the presence or absence of soluble VCAM-Fc fusion protein (sVCAM-Fc) or immobilized VCAM-Fc. sVCAM-Fc induced a concentration-dependent increase in LTC4 secretion, which was dependent on the presence of PAF and not blocked by cyclic peptides shown to inhibit α4β1-dependent adhesion. Likewise, soluble ICAM-Fc induced a concentration- dependent LTC4 secretion. LTC4 secretion was induced by the calcium ionophore, A23187, and the combination of sVCAM-Fc and A23187 had synergistic properties. It is interesting to note that Mn2+ or anti-β1 monoclonal antibody, TS2/16, inhibited LTC4 secretion induced by sVCAM-Fc and PAF. Eosinophil adhesion to VCAM-Fc or interleukin-1β-stimulated endothelial cells did not induce LTC4 secretion. These data suggest that sVCAM-Fc-induced LTC4 secretion depends on distinct signals from those of eosinophil adhesion. J. Leukoc. Biol. 65: 71–79; 1999.
Comparison of suppressive effects of a new anti-inflammatory compound, FR167653, on production of PGE2 and inflammatory cytokines, human monocytes, and alveolar macrophages in response to endotoxin
Authors: Kawano Tetsuya , Ogushi Fumitaka , Tani Kenji , Endo Takeshi , Ohmoto Yasukazu , Hayashi Yoko , Sone Saburo
Published: January 2018

FR167653 {1-[7-(4-fluorophenyl)-1, 2, 3, 4-tetrahydro-8 (4-pyridyl) pyrazoro [5-1-c] [1, 2, 4] triazin-2-yl]-2-phenylethanedion sulfate monohydrate} was developed to inhibit proinflammatory cytokine production. However, the effects of FR167653 on prostanoid production are unclear. We investigated the effect of FR167653 on proinflammatory cytokine and prostaglandin (PG) production by lipopolysaccharide (LPS)-stimulated human peripheral blood monocytes and alveolar macrophages (AM) from the same individuals, and compared the effects in monocytes and AM. FR167653 inhibited interleukin-1β and tumor necrosis factor a production. The effect on PGE2 production was assessed by four parameters. FR167653 inhibited PGE2 synthesis and LPS induction of cyclooxygenase activity. Western and Northern blot analyses revealed that LPS induction of cyclooxygenase-2 expression was attenuated by this compound. The suppression in monocytes was greater than that in AM. We concluded that the reduction of LPS-induced PGE2 synthesis by FR167653 was due to inhibition of cyclooxygenase-2 production. These results show that FR167653 may be therapeutically useful for inhibiting production of both inflammatory cytokines and PG production in inflammatory diseases. J. Leukoc. Biol. 65: 80–86; 1999.
Trp-Lys-Tyr-Met-Val-D-Met stimulates superoxide generation and killing of Staphylococcus aureus via phospholipase D activation in human monocytes
Authors: Bae Yoe-Sik , Ju Seong-A , Kim Ji Yung , Seo Jeong Kon , Baek Suk Hwan , Kwak Jong-Young , Kim Byung Sam , Suh Pann-Ghill , Ryu Sung Ho
Published: January 2018

Among the phagocytic leukocytes, monocytes have the important role of clearing out parasitic microorganisms. They accomplish this through production of toxic metabolites of oxygen. Trp-Lys-Tyr-Met-Val-D-Met (WKYMVm), a peptide that stimulates phosphoinositide (PI) hydrolysis in human leukocytes, including monocytes, binds to a unique cell surface receptor and stimulates superoxide generation, killing of Staphylococcus aureus, and activation of phospholipase D (PLD) in human monocytes. Preincubation of the cells with a PI-specific phospholipase C (PLC) inhibitor (U-73122), protein kinase C inhibitor (GF109203X), or intracellular Ca2+ chelator (BAPTA/AM) before the peptide stimulus totally inhibits the peptide-induced PLD activation and superoxide generation. On the other hand, tyrosine kinase inhibitor genistein only partially inhibits the peptide-induced processes. The peptide-induced bacteria killing activity shares regulatory mechanisms for PLD activation with the superoxide generation, which is inhibited in the presence of 1-butanol. We suggest that the peptide stimulates PLD downstream of PLC activation and PLD activation in turn is essential for the peptide-induced immunological functions such as the superoxide generation and killing of bacteria by human monocytes. J. Leukoc. Biol. 65:241–248; 1999.
LPS down-regulates the expression of chemokine receptor CCR2 in mice and abolishes macrophage infiltration in acute inflammation
Authors: Zhou Yuhong , Yang Yi , Warr Glenn , Bravo Rodrigo
Published: January 2018

Interactions between chemokines and their specific receptors are important for leukocyte trafficking. The CC-chemokine monocyte chemoattractant protein-1 (MCP-1) and its specific receptor CCR2 are essential in monocytic infiltration and have been associated with several inflammatory diseases. It has been reported that several endotoxin and proinflammatory cytokines inhibit CCR2 expression in vitro in human monocytes. We report here that lipopolysaccharides (LPS) down-regulated CCR2 expression both in vitro and in vivo. Injection of LPS into mice dramatically reduced the expression of CCR2 on the surface of peripheral blood cells and completely blocked macrophage infiltration into the peritoneal cavity in response to thioglycollate elicitation. In addition, treatment of mice with LPS reduced their efficiency to clear Listeria monocytogenes infection. These results suggest that down-regulation of CCR2 and blockage of monocyte infiltration may contribute to the inhibition of macrophage function in vivo by a low dose of LPS. J. Leukoc. Biol. 65: 265–269; 1999.
Regulation of arachidonic acid release and cytosolic Phospholipase A2 activation
Authors: Gijón Miguel A , Leslie Christina C
Published: January 2018

The 85-kDa cytosolic PLA2 (CPLA2) mediates agonist-induced arachidonic acid release in many cell models, including mouse peritoneal macrophages. cPLA2 is regulated by an increase in intracellular calcium, which binds to an amino- terminal C2 domain and induces its translocation to the nuclear envelope and endoplasmic reticulum. Phosphorylation of cPLA2 on S505 by mitogen-activated protein kinases (MAPK) also contributes to activation. In macrophages, zymosan induces a transient increase in intracellular calcium and activation of MAPK, which together fully activate cPLA2 and synergistically promote arachidonic acid release. There are alternative pathways for regulating cPLA2 in macrophages because PMA and okadaic acid induce arachidonic acid release without increasing calcium. The baculovirus expression system is a useful model to study cPLA2 activation. Sf9 cells expressing cPLA2 release arachidonic acid to either A23187 or okadaic acid. cPLA2 is phosphorylated on multiple sites in Sf9 cells, and phosphorylation of S727 is preferentially induced by okadaic acid. However, the phosphorylation sites are non-essential and only S505 phosphorylation partially contributes to cPLA2 activation in this model. Although okadaic acid does not increase intracellular calcium in Sf9 cells, calcium binding by the C2 domain is necessary for arachidonic acid release. A23187 and okadaic acid activate cPLA2 by different mechanisms, yet both induce translocation to the nuclear envelope in Sf9 cells. The results demonstrate that alternative regulatory pathways can lead to cPLA2 activation and arachidonic acid release. J. Leukoc. Biol. 65: 330–336; 1999.
Kinases involved in MSP/RON signaling
Authors: Danilkovitch Alla , Leonard Edward J
Published: January 2018

Macrophage stimulating protein (MSP) belongs to the plasminogen-related kringle domain family. In addition to stimulation of macrophages, MSP acts on other cell types including epithelial and hematopoietic cells. The MSP receptor is a transmembrane tyrosine kinase called RON in humans and STK in mice. MSP/receptor interaction induces activation of signal transduction pathways that mediate MSP biological activities. Cytoplasmic kinases are intracellular messengers occupying an important role in signal transduction. We have identified kinases that participate in RON signaling. In addition to previously identified involvement of phosphatidylinositol 3-kinase (PI3-K), JNK, and MAPK, we found that FAK, c-Src, and AKT are rapidly and transiently activated by MSP. FAK, MAPK, and c-Src are involved in MSP-induced cell proliferation. MAPK and c-Src are components of one signal transduction cascade, and MAPK is downstream of c-Src. FAK also regulates MSPinduced cell growth, but via a path different from c-Src/MAPK. AKT kinase is a component of a separate branch of the RON/PI3-K pathway that mediates the MSP anti-apoptotic effect on epithelial cells. PI3-K regulates MSP-induced adhesion and motility but via downstream components different from AKT. Thus, occupancy of the RON receptor by MSP activates distinct signal transduction pathways that mediate several cellular responses. J. Leukoc. Biol. 65: 345–348; 1999.
Antibodies to CD18 influence neutrophil migration through extracellular matrix
Authors: Saltzman W Mark , Livingston Treena L , Parkhurst Maria R
Published: January 2018

Mac-1 (CD11b/CD18) is known to be involved in neutrophil (PMN) adhesion to endothelial cells and extracellular matrix. Although antibodies to CD18 are being tested for therapy in humans, their role in PMN migration through the extracellular matrix is unknown. We used direct visualization to quantify PMN motility through reconstituted, three-dimensional gels of collagen type I. Gels were prepared with different concentrations of collagen (ranging from 0.1 to 1.0 mg/mL) and PMN migration was examined in the presence and absence of antibodies to CD18 (anti-CD18), with and without stimulation by N-formyl peptides. In low-concentration gels (<0.6 mg/mL), anti-CD18 had a significant influence on PMN migration, increasing motility in unstimulated PMN by 90% at 0.3 mg/mL collagen, and decreasing motility in N-formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated PMN by 70% at 0.4 mg/mL collagen. But anti-CD18 had no effect on the rate of cell migration through high-concentration collagen gels (>0.6 mg/mL). PMN migration through collagen gels is CD18-dependent but only under conditions of high hydration, suggesting that CD18-mediated effects (e.g., adhesion to gel fibers) are only important when the fiber density is relatively low. Anti-CD18 inhibited, but did not eliminate, the adhesion of fMLP-stimulated PMN to the surface of collagen gels, suggesting that cells use multiple mechanisms for gaining traction within the gel. Because of the multiple modes of interaction between motile cells and the deformable fiber matrix, blockade of one component, such as CD18, can enhance the rate of cell migration under one set of conditions, and inhibit under another. J. Leukoc. Biol. 65: 356–363; 1999.
Neutrophils isolated from leprosy patients release TNF-α and exhibit accelerated apoptosis in vitro
Authors: Oliveira R B , Moraes M O , Oliveira E B , Sarno E N , Nery J A C , Sampaio E P
Published: January 2018

This study demonstrated that polymorphonuclear neutrophils (PMN) participate in the acute inflammatory response in leprosy as effector cells. Lepromatous patients present intense infiltrate of neutrophils in reactional (ENL) lesions. Circulating PMN of nonreactional patients, healthy donors, and reactional patients were purified and analyzed in vitro. The study confirmed the short lifespan of these cells in culture with progressive changes characteristic of apoptosis. Apoptosis was greatly accelerated in ENL patients as shown by cellular morphology, later confirmed by qualitative and quantitative analysis of fragmented DNA. It was observed that neutrophils stimulated with lipopolysaccharide, Mycobacterium leprae, and lipoarabinomannan secrete interleukin-8 and tumor necrosis factor α (TNF-α). Thalidomide, a drug known to inhibit TNF-α synthesis on monocytes, also exerted an inibitory effect on TNF-α secretion in neutrophils. These data suggest that PMN can participate in the regulation of the immune response in leprosy and can contribute to the amplification of TNF-α production at the site of ENL lesion. J. Leukoc. Biol. 65: 364–371; 1999.
Co-expression of several human syntaxin genes in neutrophils and differentiating HL-60 cells: variant isoforms and detection of syntaxin 1
Authors: Martín-Martín Belén , Nabokina Svetlana M , Lazo Pedro A , Mollinedo Faustino
Published: January 2018

Syntaxins are major components of vesicle trafficking and their pattern of expression depends on the cell type. Using reverse transcriptase-polymerase chain reaction (RT-PCR), cloning, and sequencing techniques, we have found that human neutrophils and neutrophil-differentiated HL-60 cells co-express syntaxins 1A, 3, 4, 5, 6, 7, 9, 11, and 16. These genes are also expressed in human peripheral blood lymphocytes and SH-SY5Y neuroblastoma cells, which, unlike neutrophils, also expressed syntaxin 10. We have identified two isoforms of syntaxin 3. Syntaxin 3A, similar to the previously reported syntaxin 3, and the novel isoform syntaxin 3B, which is identical to syntaxin 3A but lacks 37 amino acid residues at the carboxy-terminal region. Syntaxin 1 was mainly located to neutrophil granule membranes by confocal microscopy and by immunoblotting of subcellular fractions. These data indicate that syntaxin 1 cannot be considered specific to neural tissues. The level of expression of syntaxins 3, 4, 6, and 11 was increased during neutrophil differentiation ofHL-60 cells, whereas that of syntaxins 1A, 5, 9, and 16 was unchanged. Syntaxin 7 was not expressed in undifferentiated HL-60 cells, but its expression was induced on neutrophil differentiation. The expression of several syntaxin genes in human neutrophils could be related to the high secretory capacity of these cells as well as to the presence of different cytoplasmic granules with distinct exocytic capabilities. J. Leukoc. Biol. 65: 397–406; 1999.
Viral variant nucleotide sequences help expose leukocytic positioning in the JC virus pathway to the CNS
Authors: Jensen Peter N , Major Eugene O
Published: January 2018

The human polyomavirus JCV lytically infects oligodendrocytes of immunosuppressed individuals leading to the fatal demyelinating disease termed progressive multifocal leukoencephalopathy (PML). Dementia, hemiparesis, and hemianopsia are the predominant presenting signs of PML. Asymptomatic JCV infection is common worldwide with approximately 80% of adults testing positive for JCV antibodies. In addition to the brain, JCV has been shown to infect tonsil, lymphoid, bone marrow, and kidney tissues. Viral variants, classified according to the nucleotide sequences of their regulatory regions, are being mapped in human tissues and cell types to help trace the pathway of JCV from a site of initial infection to target oligodendrocytes. In most literature, a dichotomy of the JCV regulatory region structure exists by tissue. B lymphocytes, however, have demonstrated the capacity to harbor JCV of diverse regulatory regions, which helps position their interaction with virus amid every stage of infection and implicates a lymphocytic role in latency. J. Leukoc. Biol. 65: 428–438; 1999.
Interferon response heterogeneity: activation of a pro-inflammatory response by interferon α and β. A possible basis for diverse responses to interferon β in MS
Authors: Jansen Marilyn , Reinhard John F
Published: January 2018

Interferon γ (IFN-γ) stimulates the (pro-inflammatory) type II interferon receptor and is known to exacerbate multiple sclerosis (MS). In contrast, IFN-α and IFN-β are ligands for the (anti-inflammatory) type I interferon receptor and are beneficial in some (but not all) patients with MS. Should IFN-β elicit a type-II-like pro-inflammatory response, the beneficial effects might be attenuated. These studies were undertaken to test this possibility with the use of quinolinic acid (QUIN) formation as a measure of type II receptor activation. In normal human macrophage cultures, IFN-γ was the most potent stimulus for QUIN formation. Generally, IFN-β and IFN-α were less potent. However, an unexpected inter-patient variability was observed. In some subjects, IFN-α was more potent than IFN-β. In other subjects, IFN-β was more potent than IFN-α. The present data demonstrate an inter-subject variability for QUIN production following exposure to the interferons. MS patients who demonstrate a pro-inflammatory response to IFN-β (e.g., increased QUIN) may be less likely to benefit from this therapy. J. Leukoc. Biol. 65: 439–443; 1999.
Do alcohol and cocaine abuse alter the course of HIV-associated dementia complex?
Authors: Tyor William R , Middaugh Lawrence D
Published: January 2018

Although psychoactive drugs are commonly used by AIDS patients, it is unclear whether commonly abused drugs, such as cocaine and ethanol, affect the course of HIV-associated dementia (HADC). Epidemiological studies have resulted in conflicting conclusions as to what role, if any, abused drugs play in HADC. In this review we discuss the clinical and pathological evidence that cocaine and ethanol might exacerbate the detrimental effects of HIV infection on the brain. We also review studies of cocaine and ethanol effects on various components of the immune system both in the presence and absence of retroviral infection. Data from these studies indicate that cocaine and ethanol have profound effects on the immune system that, in many respects, are enhanced by retroviral infection. We conclude that abused drugs likely affect the course of HADC but that proof awaits an examination of their interactive effects in an appropriate in vivo system of retroviral encephalitis. J. Leukoc. Biol. 65: 475–481; 1999.
NADPH oxidase is functionally assembled in specific granules during activation of human neutrophils
Authors: Vaissiere Clémence , Le Cabec Véronique , Maridonneau-Parini Isabelle
Published: January 2018

In addition to the extracellular production of O2− by NADPH oxidase in neutrophils stimulated by soluble stimuli, the intracellular formation of oxygen reactive species has been described. Cytochrome b559, the redox component of the NADPH oxidase complex, is mainly associated with specific granule membrane in resting neutrophils. We examined whether these granules could be a site for intracellular production of O2−. Phorbol myristate acetate (PMA)-stimulated neutrophils were fractionated by differential centrifugation, and generation of O2− was detected in both the granule and the plasma membrane-enriched fractions, but more in the granules. Translocation of p47phox and p67phox, two cytosolic components of the NADPH oxidase, was also quantitatively more important in the granules than in the plasma membrane fraction. After separation of the specific from the azurophil granules, p47phox and p67phox were found to be present only in the specific granules of PMA-activated cells. As a control, the production of O2− was studied in retinoic acid-differentiated NB4 cells that lack specific granules. During stimulation of NB4 cells with PMA, only the plasma membrane-enriched fraction was the site of O2− production. Together, these results indicate that NADPH oxidase can be functionally assembled in specific granules. J. Leukoc. Biol. 65: 629–634; 1999.
Cloning of two chemokine receptor homologs (CXC-R4 and CC-R7) in rainbow trout Oncorhynchus mykiss
Authors: Daniels Garry D , Zou Jun , Charlemagne Jacques , Partula S , Cunningham Charles , Secombes Christopher J
Published: January 2018

Two rainbow trout chemokine receptors have been sequenced, with homology to CXC-R4 and CC-R7 molecules. The CXC-R4 sequence consisted of 1681 nucleotides, which translated into a mature protein of 357 amino acids, with 80.7% similarity to human CXC-R4. The CC-R7 sequence consisted of 2287 nucleotides, which translated into a 368-amino acid mature protein with 64.5% similarity to human CC-R7. Both sequences contained seven hydrophobic regions, representing the seven transmembrane domains (TM) typical of G-protein-coupled receptors. Extracellular cysteines, transmembrane prolines, and the DRY motif immediately following TM3 were conserved. Phylogenetic tree analysis revealed a tight clustering of trout CXC-R4 with CXC-R3-5 genes. Trout CC-R7 clustered with CC-R6-7 and CXC-R1-2. Reverse transcriptase-polymerase chain reaction analysis demonstrated a wide tissue distribution of CXC-R4 and CC-R7 message in trout, being present in head-kidney leukocytes, blood, gill, brain, spleen, and liver. J. Leukoc. Biol. 65: 684–690; 1999.
Dysregulation of PMN antigen expression in Type 2 diabetes may reflect a generalized defect of exocytosis: influence of hypertension and microalbuminuria
Authors: Senior Peter A , Marshall Sally M , Thomas Trevor H
Published: January 2018

Defective exocytosis could underlie clinical and metabolic abnormalities in Type 2 diabetes. Because many SNARE proteins appear to be common mediators of exocytosis, we examined phorbol myristate acetate-stimulated expression of CD11b and CD69 on polymorphonuclear leukocytes (PMN) from Type 2 diabetic subjects with hypertension and microalbuminuria (D-htma), hypertension only (D-ht) or uncomplicated (D-uc), and normal controls (NC) by flow cytometry. CD11b expression was rapid (half maximal by 7 min), initially on all PMN. CD69 expression took place subsequently but on PMN that did not express CD11b. The proportion of CD11b-positive PMN at 30 min was higher in all diabetic groups than in NC. Expression of CD11b was higher and CD69 lower in D-uc and D-htma but were similar in NC and D-ht. In Type 2 diabetes the transition from the CD11b-positive to CD69-positive state is impaired. The defect in the process of CD69 expression appeared most marked in diabetic subjects with hypertension and microalbuminuria. J. Leukoc. Biol. 65: 800–807; 1999.
Mycoplasma arginini enhances cytotoxicity of thioglycollate-elicited murine macrophages toward YAC-1 tumor cells through production of NO
Authors: Ribeiro-Dias Fátima , Russo Momtchilo , Marzagão Barbuto José Alexandre , Raquel Flávia , do Nascimento Fernandes , Timenetsky Jorge , Jancar Sonia
Published: January 2018

Bacterial products stimulate macrophage tumoricidal activity through release of tumor necrosis factor (TNF) and nitric oxide (NO). We show here that thioglycollate-elicited macrophages acquire cytotoxic activity when cocultured with Mycoplasma arginini-infected YAC-1 tumor cells and release TNF and NO. Fixed mycoplasma-infected cells, supernatants from infected-cell cultures, or purified heat-killed mycoplasma obtained from cell-free cultures were all able to induce TNF and NO production. Thus, the mycoplasma per se and not a product of infected cells induce the release of these molecules. Addition of prostaglandin E2 (PGE2) to the cocultures, which reduced TNF release, or antibodies to TNF, did not affect macrophage cytotoxicity nor NO release. Inhibition of NO production by L-NAME or aminoguanidine reduced the cytotoxicity, and treatment with a NO donor was toxic to YAC-1 cells. These results indicate that M. arginini activates thioglycollate-elicited murine macrophages for NO and TNF release increasing their cytotoxic activity toward YAC-1 cells and that this activity is dependent on NO but not TNF release. J. Leukoc. Biol. 65: 808–814; 1999.
Identification of the CD85 antigen as ILT2, an inhibitory MHC class I receptor of the immunoglobulin superfamily
Authors: Banham Alison H , Colonna Marco , Cella Marina , Micklem Kingsley J , Pulford Karen , Willis Antony C , Mason David Y
Published: January 2018

The CD85 molecule was originally defined at the Fifth Workshop on Leucocyte Antigens in 1993 by two monoclonal antibodies, VMP55 and GHI/75. This cell-surface glycoprotein is expressed on B cells, monocytes, and subpopulations of T and natural killer (NK) cells, and particularly high levels are expressed by normal and neoplastic plasma cells and by hairy cell leukemia B cells. We affinity purified the CD85 antigen and obtained tryptic peptide sequence which indicated that this molecule might be ILT2, a recently described inhibitory major histocompatibility complex class I receptor of the immunoglobulin superfamily. This was confirmed by showing that both of the original anti-CD85 mAbs stained ILT2 transfectants. The cell signaling role demonstrated for ILT2 is consistent with the previously reported involvement of CD85 in T cell activation. J. Leukoc. Biol. 65: 841–845; 1999.
Protein kinase C and a calcium-independent phospholipase are required for IgG-mediated phagocytosis by Mono-Mac-6 cells
Authors: Karimi Kambiz , Gemmill Trent R , Lennartz Michelle R
Published: January 2018

Mono-Mac-6 (MM6) human monocytes ingest IgG-opsonized particles better than other human cell lines. We compared the phagocytic signaling pathway in MM6 with human monocytes. MM6 expressed FcγRI at levels similar to monocytes, whereas FcRγII expression was approximately double. MM6 ingested IgG-opsonized erythrocytes (EIgG) in a calcium-independent manner. Incubation of MM6 with bromoenol lactone, an inhibitor of the phagocytic phospholipase (pPL), coordinately decreased phagocytosis and pPL activity. This inhibition was overcome by exogenous arachidonic acid, suggesting that phagocytosis requires pPL activation and arachidonic acid release. MM6 phagocytosis was inhibited with staurosporine and activated with diacylglycerol, supporting a role for protein kinase C (PKC) in this process. The pPL activators mastoparan and melittin restored phagocytosis to PKC-inhibited cells, suggesting that pPL lies downstream from PKC. These results suggest that the MM6 signal transduction pathway for IgG-mediated phagocytosis is similar to that of monocytes (PKC→pPL→arachidonic acid→phagocytosis). The results are discussed in the context of the finding that MM6 exhibit low phagocytosis relative to monocytes and thus may represent an attractive cell line for molecular manipulation in “recovery of function” studies. J. Leukoc. Biol. 65: 854–862; 1999.
Tyrphostin AG-490 inhibits cytokine-mediated JAK3/STAT5a/b signal transduction and cellular proliferation of antigen-activated human T cells
Authors: Kirken Robert A , Erwin Rebecca A , Taub Dennis , Murphy William J , Behbod Fariba , Wang Lihua , Pericle Federica , Farrar William L
Published: January 2018

Janus kinase 3 (JAK3) is a cytoplasmic tyrosine kinase required for T cell development and activated by cytokines that utilize the interleukin-2 (IL-2) receptor common gamma chain (γc). Genetic inactivation of JAK3 is manifested as severe combined immunodeficiency disease (SCID) in humans and mice. These findings have suggested that JAK3 represents a pharmacological target to control certain lymphoid-derived diseases. Here we provide novel evidence that AG-490 potently inhibits the autokinase activity of JAK3 and tyrosine phosphorylation and DNA binding of signal transducer and activator of transcription 5a and 5b (STAT5a/b). Similar inhibitory effects were observed with other cytokines that use γc. AG-490 also inhibited IL-2-mediated proliferative growth in human T cells with an IC50 = 25 μM that was partially recoverable. Moreover, we demonstrate that this inhibitor prevented tetanus toxoid antigen-specific T cell proliferation and expansion but failed to block activation of Zap70 or p56Lck after anti-CD3 stimulation of human T cells. Taken together, these findings suggest that AG-490 inhibits the JAK3-mediated Type II signaling pathway but not the T cell receptor-derived Type I pathway and possesses therapeutic potential for T cell-derived pathologies such as graft-versus-host disease, allergy, and autoimmune disorders. J. Leukoc. Biol. 65: 891–899; 1999.
MHC class II-dependent activation of CD4+ T cell hybridomas by human mast cells through superantigen presentation
Authors: Poncet Pascal , Arock Michel , David Bernard
Published: January 2018

Human mast cells (MC) were examined for expression of MHC class II antigens and for their ability to activate CD4+ T cell hybridomas through presentation of superantigen (SAg). HMC-1, a leukemic immature MC line expressing class II Ags, was shown to efficiently present the staphylococcal enterotoxin B (SEB) SAg to responding T cell hybridoma on treatment with interferon-γ (IFN-γ), which up-regulated class II molecules. The study was then extended to human normal MC. Almost pure (>99%) cord blood-derived MC (CBMC) were shown to express class II Ags (HLA-Dr and HLA-DQ) and CD80, which were up-regulated by IFN-γ treatment and, to a lesser extent, by interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF). CBMC directly activated CD4+ T cell hybridomas through presentation of SEB and TSST1 SAgs. The production of IL-2 required a cell-to-cell contact between T cells and CBMC and it was inhibited by anti-class II antibodies. Furthermore, an additional pretreatment of CBMC by IFN-γ or GM-CSF or IL-4 had no effect on their presenting efficiency. This previously unknown function of human MC, i.e., MHC class II-dependent activation of CD4+ T cells, may be critical in subsequent cellular activation events because colocalization of mast and T cells is frequently observed at sites of antigen entry. J. Leukoc. Biol. 66: 105–112; 1999.