scholarly journals Modulation of polymorphonuclear leukocyte function by cetiedil

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 274-279
Author(s):  
JB Wolach ◽  
TD Coates ◽  
DY Tzeng ◽  
RL Baehner ◽  
LA Boxer
Keyword(s):  
Polymorphonuclear Leukocyte ◽  
Myristate Acetate ◽  
Leukocyte Function ◽  
Dose Dependent Fashion ◽  
Induced Aggregation ◽  
Dose Dependent ◽  
Aggregation Of Platelets ◽  
Primary Granule ◽  
Granule Product

Cetiedil citrate monohydrate inhibits sickling of red cells and aggregation of platelets. We assessed its ability to attenuate polymorphonuclear leukocyte (PMN) function. PMN aggregation in response to 2 X 10(-7) M formyl-met-leu-phe (FMLP) was inhibited in a dose- dependent fashion by cetiedil concentrations ranging from 60 to 250 microM. Additionally, 125 microM cetiedil inhibited PMN aggregation in response to 2 X 10(-7) M FMLP, 20 ng/ml phorbol myristate acetate (PMA), and 1 X 10(-6) M A23187 by 69% +/- 18%, 72% +/- 20%, and 65% +/- 4%, respectively. Inhibition of FMLP-induced aggregation was provided by only 5 min of incubation of the drug with the cells and was partially reversible. Cell viability was unaffected by exposure of PMN to the drug. Correspondingly, 125 microM cetiedil prevented the translocation of calcium from the PMN membrane as assessed by chlorotetracycline fluorescence. Paralleling the effect of the drug on PMN aggregation, 125 microM cetiedil inhibited release of superoxide by 55% and decreased the number of available 3H-FMLP receptors. However, its effect on release of the primary granule constituent, myeloperoxidase, was minimal (4.5% inhibition), while the effect on release of the specific granule product, lactoferrin (27% inhibition), was modest. These studies indicate that cetiedil affects PMN aggregation and superoxide release to a much greater extent than PMN degranulation. Thus, cetiedil may have potential uses in modulating inflammatory response in vivo.

scholarly journals Modulation of polymorphonuclear leukocyte function by cetiedil

Blood ◽  
1983 ◽  
Vol 62 (2) ◽  
pp. 274-279 ◽  
Author(s):  
JB Wolach ◽  
TD Coates ◽  
DY Tzeng ◽  
RL Baehner ◽  
LA Boxer
Keyword(s):  
Polymorphonuclear Leukocyte ◽  
Myristate Acetate ◽  
Leukocyte Function ◽  
Dose Dependent Fashion ◽  
Induced Aggregation ◽  
Dose Dependent ◽  
Aggregation Of Platelets ◽  
Primary Granule ◽  
Granule Product

Abstract Cetiedil citrate monohydrate inhibits sickling of red cells and aggregation of platelets. We assessed its ability to attenuate polymorphonuclear leukocyte (PMN) function. PMN aggregation in response to 2 X 10(-7) M formyl-met-leu-phe (FMLP) was inhibited in a dose- dependent fashion by cetiedil concentrations ranging from 60 to 250 microM. Additionally, 125 microM cetiedil inhibited PMN aggregation in response to 2 X 10(-7) M FMLP, 20 ng/ml phorbol myristate acetate (PMA), and 1 X 10(-6) M A23187 by 69% +/- 18%, 72% +/- 20%, and 65% +/- 4%, respectively. Inhibition of FMLP-induced aggregation was provided by only 5 min of incubation of the drug with the cells and was partially reversible. Cell viability was unaffected by exposure of PMN to the drug. Correspondingly, 125 microM cetiedil prevented the translocation of calcium from the PMN membrane as assessed by chlorotetracycline fluorescence. Paralleling the effect of the drug on PMN aggregation, 125 microM cetiedil inhibited release of superoxide by 55% and decreased the number of available 3H-FMLP receptors. However, its effect on release of the primary granule constituent, myeloperoxidase, was minimal (4.5% inhibition), while the effect on release of the specific granule product, lactoferrin (27% inhibition), was modest. These studies indicate that cetiedil affects PMN aggregation and superoxide release to a much greater extent than PMN degranulation. Thus, cetiedil may have potential uses in modulating inflammatory response in vivo.

scholarly journals Aggregation of Streptococcus pneumoniae by a Pneumococcal Capsular Polysaccharide-Specific Human Monoclonal IgM Correlates with Antibody Efficacy In Vivo

2010 ◽  
Vol 17 (5) ◽  
pp. 713-721 ◽  
Author(s):  
Kevin Fabrizio ◽  
Catherine Manix ◽  
Allan J. Guimaraes̃ ◽  
Joshua D. Nosanchuk ◽  
Liise-anne Pirofski
Keyword(s):  
Streptococcus Pneumoniae ◽  
Cellular Proliferation ◽  
Capsular Polysaccharide ◽  
Bactericidal Effect ◽  
Lethal Challenge ◽  
Dose Dependent Fashion ◽  
Induced Aggregation ◽  
Dose Dependent

ABSTRACT Acquired antibody immunity to Streptococcus pneumoniae (pneumococcus) has been linked to serotype (ST)-specific opsonic antibodies to the relevant pneumococcal capsular polysaccharide (PPS) that mediate protection by enhancing the bactericidal effect of host phagocytes. Despite the well-recognized role of opsonic IgG in host defense against pneumococcus, PPS-specific monoclonal antibodies (MAbs) that mediate protection against lethal challenge with ST3 pneumococcus in mice but do not promote phagocytic killing in vitro (nonopsonic antibodies) have been described. In this study, we sought to determine the biological activity of one such MAb, A7 (a human PPS3-specific IgM), and the mechanism by which it mediates protection. In vitro studies demonstrated that coincubation of A7 with ST3 in the absence of phagocytes or a complement source resulted in a reduction in CFU on blood agar plates that was largely reversible by sonication. A chromogenic cellular proliferation assay demonstrated that A7 did not affect replication of ST3 in liquid culture. The ability of A7 to induce aggregation of ST3 was confirmed by fluorescence microscopy and flow cytometry: A7 induced aggregation of ST3, and in the presence of a complement source, A7 promoted deposition of complement component 3 (C3) on aggregated bacteria in a dose-dependent fashion. Similarly, administration of preincubated mixtures of A7 and ST3 intraperitoneally to mice protected them from the lethality of ST3 in a dose-dependent fashion. These findings suggest that A7-mediated aggregation enhances resistance to ST3, most likely by enhancing C3 deposition on the ST3 capsule, thereby promoting host antipneumococcal activity in vivo.

Soluble Thrombomodulin Purified from Human Urine Exhibits a Potent Anticoagulant Effect In Vitro and In Vivo

1995 ◽  
Vol 73 (05) ◽  
pp. 805-811 ◽  
Author(s):  
Yasuo Takahashi ◽  
Yoshitaka Hosaka ◽  
Hiromi Niina ◽  
Katsuaki Nagasawa ◽  
Masaaki Naotsuka ◽  
...  
Keyword(s):  
Human Urine ◽  
Specific Activity ◽  
Anticoagulant Activity ◽  
Rabbit Lung ◽  
Soluble Thrombomodulin ◽  
Molecular Weights ◽  
Dose Dependent Fashion ◽  
Dose Dependent

SummaryWe examined the anticoagulant activity of two major molecules of soluble thrombomodulin purified from human urine. The apparent molecular weights of these urinary thrombomodulins (UTMs) were 72,000 and 79,000, respectively. Both UTMs showed more potent cofactor activity for protein C activation [specific activity >5,000 thrombomodulin units (TMU)/mg] than human placental thrombomodulin (2,180 TMU/mg) and rabbit lung thrombomodulin (1,980 TMU/mg). The UTMs prolonged thrombin-induced fibrinogen clotting time (>1 TMU/ml), APTT (>5 TMU/ml), TT (>5 TMU/ml) and PT (>40 TMU/ml) in a dose-dependent fashion. These effects appeared in the concentration range of soluble thrombomodulins present in human plasma and urine. In the rat DIC model induced by thromboplastin, administration of UTMs by infusion (300-3,000 TMU/kg) restored the hematological abnormalities derived from DIC in a dose-dependent fashion. These results demonstrate that UTMs exhibit potent anticoagulant and antithrombotic activities, and could play a physiologically important role in microcirculation.

Role Of Cyclic Amp In The Inhibition Of Human Platelet Functions By Quercetin, A Flav0N0Id That Potentiates PGI2 Effect

1981 ◽  
Author(s):  
J P Cazenave ◽  
A Beretz ◽  
A Stierlé ◽  
R Anton
Keyword(s):  
Maximum Level ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Pde Inhibitors ◽  
Pde Inhibition ◽  
Induced Aggregation ◽  
Camp Levels ◽  
Dose Dependent

Injury to the endothelium (END) and subsequent platelet (PLAT)interactions with the subEND are important steps in thrombosis and atherosclerosis. Thus,drugs that protect the END from injury and also inhibit PLAT function are of interest. It has been shown that some flavonoids(FLA), a group of compounds found in plants, prevent END desquamation in vivo, inhibit cyclic nucleotide phosphodiesterases(PDE)and inhibit PLAT function. We have studied the structure-activity relationships of 13 purified FLA on aggregation and secretion of 14c-5HT of prelabeled washed human PLAT induced by ADP, collagen(COLL) and thrombin(THR). All the FLA were inhibitors of the 3 agents tested. Quercetin(Q), was the second best after fisetin. It inhibited secretion and aggregation with I50 of 330µM against 0.1 U/ML.THR, 102µM against 5µM ADP and 40 µM against COLL. This inhibitory effect is in the range of that of other PDE inhibitors like dipyridamole or 3-isobutyl-l- methylxanthine. The aggregation induced by ADP, COLL and THR is at least mediated by 3 mechanisms that can be inhibited by increasing cAMP levels. We next investigated if Q, which is a PDE inhibitor of bovine aortic microsomes,raises PLAT cAMP levels. cAMP was measured by a protein-binding method. ADP- induced aggregation(5µM) was inhibited by PGI2 (0.1 and 0.5 nM) . Inhibition was further potentiated(l.7 and 3.3 times) by lOµM Q, which alone has no effect on aggregation. The basal level of cAMP(2.2 pmol/108PLAT) was not modified by Q (50 to 500µM). Using these concentrations of Q,the rise in cAMP caused by PGI2(0.1 and 0.5nM) was potentiated in a dose dependent manner. Q potentiated the effect of PGI2 on the maximum level of cAMP and retarded its breakdown. Thus Q and possibly other FLA could inhibit the interaction of PLAT with the components of the vessel wall by preventing END damage and by inhibiting PLAT function through a rise in cAMP secondary to PDE inhibition and potentiation of the effect of vascular PGI2 on PLAT adenylate cyclase.

Enhancement of FSH bioactivity in vivo using site-specific antisera

1997 ◽  
Vol 152 (3) ◽  
pp. 355-363 ◽  
Author(s):  
L Ferasin ◽  
G Gabai ◽  
J Beattie ◽  
G Bono ◽  
A T Holder
Keyword(s):  
Biological Activity ◽  
Treatment Period ◽  
Ovarian Function ◽  
Day Treatment ◽  
Site Specific ◽  
Dose Dependent Fashion ◽  
Snell Dwarf ◽  
Fsh Bioactivity ◽  
Dose Dependent

The ability of site-specific antipeptide antisera to enhance the biological activity of ovine FSH (oFSH) in vivo was investigated using hypopituitary Snell dwarf mice. These animals were shown to respond to increasing doses of oFSH (3·3–90 μg/day), administered in two daily injections over a 5-day treatment period, in a highly significant dose-dependent fashion. The responses measured were increases in uterine weight, ovarian weight and the index of keratinisation in vaginal smears. The dose-dependent response to oFSH confirmed the suitability of this animal model for these investigations and suggested the suboptimal dose of oFSH (20 μg/day) for use in enhancement studies. Five peptides derived from the β subunit of bovine FSH (bFSH) (A, residues 33–47; B, 40–51; C, 69–80; D, 83–94; E, 27–39) were used to generate polyclonal antipeptide antisera. Of these peptides, only A and B produced an antiserum (raised in sheep) capable of recognising 125I-bFSH in a liquid phase RIA. Antisera prepared against peptide A or peptide B were found to significantly enhance the biological activity of 20 μg oFSH/day over a 5-day treatment period. The response to antipeptide antisera alone did not differ significantly from that observed in PBS-injected control animals, neither did the response to FSH alone differ from that observed in animals treated with FSH plus preimmune serum. Thus the enhanced responses are dependent upon the presence of FSH plus antipeptide antiserum. Peptides A and B are located in a region thought to be involved in receptor recognition, this may have implications for the mechanism underlying this phenomenon and/or the structure/function relationships of FSH. That FSH-enhancing antisera can be generated by immunisation of animals with peptides A and B suggests that it may be possible to develop these peptides as vaccines capable of increasing reproductive performance, such as ovulation rate. The high degree of sequence homology between ovine, bovine and porcine (and to a lesser extent human and equine) FSH in the region covered by peptides A and B suggests that these peptides could also be used to promote and regulate ovarian function in all of these species. Journal of Endocrinology (1997) 152, 355–363

scholarly journals Interleukin-6 is a potent thrombopoietic factor in vivo in mice

Blood ◽  
1989 ◽  
Vol 74 (4) ◽  
pp. 1241-1244 ◽  
Author(s):  
T Ishibashi ◽  
H Kimura ◽  
Y Shikama ◽  
T Uchida ◽  
S Kariyone ◽  
...  
Keyword(s):  
Interleukin 6 ◽  
Serum Levels ◽  
In Vivo Studies ◽  
Time Intervals ◽  
Platelet Counts ◽  
Striking Increase ◽  
Biologic Activity ◽  
Dose Dependent Fashion ◽  
Dose Dependent

Abstract To determine the biologic activity of interleukin-6 (IL-6) on megakaryocytopoiesis and thrombocytopoiesis in vivo, the cytokine was administered intraperitoneally to mice every 12 hours at varying doses for five days or for varying time intervals, based on the kinetic analysis of IL-6 serum levels indicating the peak of 40 minutes following injection, with no detection at 150 minutes. A dose-response experiment showed that IL-6 increased platelet counts in a dose- dependent fashion at a plateau stimulation level of 5 micrograms. Administration of 5 micrograms of IL-6 reproducibly elevated platelet counts at five days by approximately 50% to 60% of increase. Moreover, a striking increase in megakaryocytic size in response to IL-6 was elicited by the treatment, but no change in megakaryocyte numbers; whereas IL-6 administration did not expand CFU-MK numbers. The in vivo studies in this manner had negligible effects on other hematologic parameters, with the minor exception of monocyte levels. These data show that IL-6 acts on maturational stages in megakaryocytopoiesis and promotes platelet production in vivo in mice, suggesting that IL-6 functions as thrombopoietin.

The Effects Of Prostacyclin (PGI2) On Intravascular Platelet Aggregation

1981 ◽  
Author(s):  
G G Duncan ◽  
G Mallarkey ◽  
G M Smith
Keyword(s):  
Platelet Count ◽  
Guinea Pigs ◽  
Adenosine Diphosphate ◽  
Before And After ◽  
Dependent Inhibition ◽  
Induced Aggregation ◽  
Dose Dependent ◽  
Anaesthetised Rats

Intravascular aggregation can be measured by counting the number of circulating platelets before and after the injection of aggregation agents. The Technicon Autocounter was modified to count platelets continuously and connected via a double cannula in a carotid artery to an anaesthetised animal.Adenosine diphosphate (ADP) and collagen gave dose- dependent falls in the circulating platelet count when injected into rats, guinea pigs and rabbits. This enabled aggregation to be accurately quantitated in vivo.The infusion of PGI2 (0.25-1 ug/kg/min) in anaesthetised rats and rabbits produced a dose-dependent inhibition of the fall in platelet count produced by ADP and collagen. The formation of PGI2 can be inhibited in vitro by 15- hydroperoxyarachidonic acid (15HPAA). When 20 ug/kg/min of 15HPAA was infused into rats, aggregation produced by collagen was significantly increased suggesting that PGI2 is continuously formed by the rat vascular endothelium. This observation was confirmed by infusing 6-keto PGF1α antiserum. This antibody also prevented the inhibitory activity of PGI2 on collagen-induced aggregation. The study of continuous platelet counting in guinea pigs has been hampered by the occurrence of thrombocytopenia in certain animals. When 2 ug/kg/min of PGI2 was infused for 10 mins, a rise in the circulating platelet count to a steady plateau 4-5 × 105 platelets occurredThese experiments have shown that PGI2 will prevent aggregation by ADP and collagen and will reverse spontaneous thrombocytopenia and that PGI2 is continuously released from the vessels of anaesthetised rats.

Inhibition Of Platelet Aggregation, Malonyldialdehyde And Thromboxane Formation By Hydroperoxides Of Arachidonic Acid

1981 ◽  
Author(s):  
D Aharonv ◽  
J B Smith ◽  
M J Silver
Keyword(s):  
Arachidonic Acid ◽  
Platelet Aggregation ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Lipoxygenase Pathway ◽  
Dose Dependent Fashion ◽  
Induced Aggregation ◽  
Layer Chromatography ◽  
Dose Dependent ◽  
Thromboxane Formation

The arachidonate hydroperoxides 12-HPETE and 15-HPETE were biosynthesized from arachidonic acid using partially purified human platelet lipoxygenase or soybean lipoxidase respectively, and isolated by thin layer chromatography. Both compounds inhibited the arachidonic acid- induced aggregation of washed human platelets, suspended in calcium-free Krebs Henseleit solution, in a dose dependent fashion at concentrations between 1 and 50 uM. No inhibition was seen with up to 100 uM of these hydroperoxides when platelet -rich plasma was used. 12-HPETE (in micromolar concentrations) inhibited the formation of both thromboxane B2 (radioimmunoassay) and malonyldialdehyde (spectrophotometrie assay) when washed platelets were incubated with arachidonic acid. The 12-hydroxide, 12-HETE also inhibited platelet aggregation and thromboxane formation, but was less potent than 12-HPETE. We suggest that arachidonate hydroperoxide generated in platelets via the lipoxygenase pathway modulates platelet aggregation induced by arachidonic acid by inhibiting thromboxane formation.

scholarly journals CTLA4 blockade expands FoxP3+ regulatory and activated effector CD4+ T cells in a dose-dependent fashion

Blood ◽  
2008 ◽  
Vol 112 (4) ◽  
pp. 1175-1183 ◽  
Author(s):  
Brian Kavanagh ◽  
Shaun O'Brien ◽  
David Lee ◽  
Yafei Hou ◽  
Vivian Weinberg ◽  
...  
Keyword(s):  
T Cells ◽  
Regulatory T Cells ◽  
Cd4 T Cells ◽  
Cytotoxic T Lymphocyte ◽  
Effector T Cells ◽  
Activated T Cells ◽  
Ctla4 Blockade ◽  
Dose Dependent Fashion ◽  
Dose Dependent

AbstractCytotoxic T lymphocyte–associated antigen 4 (CTLA4) delivers inhibitory signals to activated T cells. CTLA4 is constitutively expressed on regulatory CD4+ T cells (Tregs), but its role in these cells remains unclear. CTLA4 blockade has been shown to induce antitumor immunity. In this study, we examined the effects of anti-CTLA4 antibody on the endogenous CD4+ T cells in cancer patients. We show that CTLA4 blockade induces an increase not only in the number of activated effector CD4+ T cells, but also in the number of CD4+ FoxP3+ Tregs. Although the effects were dose-dependent, CD4+ FoxP3+ regulatory T cells could be expanded at lower antibody doses. In contrast, expansion of effector T cells was seen only at the highest dose level studied. Moreover, these expanded CD4+ FoxP3+ regulatory T cells are induced to proliferate with treatment and possess suppressor function. Our results demonstrate that treatment with anti-CTLA4 antibody does not deplete human CD4+ FoxP3+ Tregs in vivo, but rather may mediate its effects through the activation of effector T cells. Our results also suggest that CTLA4 may inhibit Treg proliferation similar to its role on effector T cells. This study is registered at http://www.clinicaltrials.gov/ct2/show/NCT00064129, registry number NCT00064129.

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