scholarly journals Complement-Dependent Action of HLA-Specific Antibodies on Human Platelets

1977 ◽  
Author(s):  
D. Heinrich ◽  
C. Mueller-Eckhardt ◽  
D. Bitter-Suermann
Keyword(s):  
Platelet Function ◽  
Complement Activation ◽  
Prostaglandin E1 ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Antimycin A ◽  
51Cr Release ◽  
Specific Antibodies ◽  
Independent Mechanism ◽  
Hla Antibody

HLA-antibody-induced platelet alterations are mediated by (a) complement-independent (Heinrich et al, Brit. J. Haematol., 35, 443, 1977) and (b) complement-dependent mechanisms. To prove the latter hypothesis platelet-rich plasma (PRP) of HLA-typed donors was incubated with HLA-specific sera and various inhibitors of platelet function (prostaglandin-E1 (PGE1), acetyl-salicylic acid (ASA), N-ethyl maleimide (NEM), adenosin, 2-desoxy-glucose + antimycin A (2-DOG + ANT.A)), furthermore an inhibitor of complement activation (cobra venom factor (CVF)) and EDTA or heparin known to interfer with platelet function and complement activation. Methods: Platelet aggregation (Born), Hc-seroto-nin release and 51Cr release. Results: Contrary to collagen-and thrombin-induced platelet alteration, PGE1, NEM, ASA, adenosin and 2-DOG+ANT. A exhibited only moderate inhibition of antibody-induced platelet alteration. However, EDTA, heparin and CVF+PGE1 strongly inhibited antibody-induced platelet alteration. The results support the concept of two pathways for specific HLA-antibody action on platelets: (a) a complement-independent mechanism resulting in aggregation and release and (b) a complement dependent, lytic mechanism.

Effects of Halothane on Platelet Function

1980 ◽  
Vol 44 (03) ◽  
pp. 143-145 ◽  
Author(s):  
J Dalsgaard-Nielsen ◽  
J Gormsen
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Halothane Anaesthesia ◽  
Inhibition Of Platelet Aggregation ◽  
Transient Impairment ◽  
High Concentrations ◽  
Uptake And Release ◽  
Platelet Functions

SummaryHuman platelets in platelet rich plasma (PRP) incubated at 37° C with 0.3–2% halothane for 5–10 min lost the ability to aggregate with ADP, epinephrine and collagen.At the same time uptake and release of 14C-serotonin was inhibited. When halothane supply was removed, platelet functions rapidly returned to normal. However, after high concentrations of halothane, the inhibition of platelet aggregation was irreversible or only partially reversible.The results suggest that halothane anaesthesia produces a transient impairment of platelet function.

Interactions of Staphylokinase with Human Platelets

1995 ◽  
Vol 73 (03) ◽  
pp. 472-477 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
D Collen
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Specific Binding ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Normal Plasma ◽  
Atp Secretion ◽  
Platelet Disaggregation ◽  
Activation Rate

SummaryThe interactions of recombinant staphylokinase (SakSTAR) with human platelets were investigated in a buffer milieu, in a human plasma milieu in vitro, and in plasma from patients with acute myocardial infarction (AMI) treated with SakSTAR.In a buffer milieu, the activation rate of plasminogen by SakSTAR or streptokinase (SK) was not significantly altered by addition of platelets. Specific binding of SakSTAR or SK to either resting or thrombin- activated platelets was very low. ADP-induced or collagen-induced platelet aggregation in platelet-rich plasma (PRP) was 94 ± 2.7% or 101 ± 1.7% of control in the presence of 0.1 to 20 μM SakSTAR, with corresponding values of 95 ± 2.8% or 90 ± 4.6% of control in the presence of 0.1 to 4 μM SK. No effects were observed on platelet disaggregation. ATP secretion following collagen-induced platelet aggregation was 4.3 ± 0.26 μM for SakSTAR (at concentrations of 0.1 to 20 μM) and 4.4 ± 0.35 μM for SK (at concentrations of 0.1 to 4 μM), as compared to 3.4 ± 0.70 μM in the absence of plasminogen activator.Fifty % lysis in 2 h (C50) of 60 μl 125I-fibrin labeled platelet-poor plasma (PPP) clots prepared from normal plasma or from plasma of patients with Glanzmann thrombasthenia and immersed in 0.5 ml normal plasma, was obtained with 12 or 16 nM SakSTAR and with 49 or 40 nM SK, respectively. C50 values for lysis of 60 μl PRP clots prepared from normal or patient plasma were also comparable for SakSTAR (19 or 21 nM), whereas SK was 2-fold more potent toward PRP clots prepared from Glanzmann plasma as compared to normal plasma (C50 of 130 versus 270 nM).No significant effect of SakSTAR on platelet function was observed in plasma from patients with AMI treated with SakSTAR, as revealed by unaltered platelet count, platelet aggregation and ATP secretion.Thus, no effects of high SakSTAR concentrations were observed on human platelets in vitro, nor of therapeutic SakSTAR concentrations on platelet function in plasma.

Depressed Responsiveness To Adrenaline In Platelets From Apparently Normal Human Donors – A Familial Trait

1981 ◽  
Author(s):  
M C Scrutton ◽  
K R Bruckdorfer ◽  
R A Hutton
Keyword(s):  
Adenylate Cyclase ◽  
Platelet Function ◽  
Divalent Cation ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
The Other ◽  
Stimulus Response ◽  
A 23187 ◽  
Phospholipid Classes ◽  
Normal Human

Decreased responsiveness to adrenaline has been observed in 5 out of approximately 150 apparently normal unrelated human donors. In 4 donors, familial studies have shown that this trait is inherited. Three of the donors, as well as their affected relatives, exhibit depressed responsiveness to collagen and vasopressin but normal responsiveness to ADP and thrombin in association with the decreased responsiveness to adrenaline. The other two affected donors exhibit normal responsiveness to most other agonists although in one instance depression of responsiveness to vasopressin and absence of a secretory response to ADP may be associated with the decreased adrenaline response.Normal responsiveness can be restored in all instances either by incubating the platelet-rich plasma at 20°C or by addition at 37°C of a low concentration of the divalent cation ionophore, A-23187. No such effect results from addition of an adenylate cyclase inhibitor. All affected platelets have normal ATP and ADP contents, cholesterol to phospholipid ratios, and composition of the phospholipid classes. Mixing experiments demonstrate the absence of a circulating inhibitor of platelet function and suggest that the defect resides in the platelets. We conclude that depressed responsiveness of human platelets to adrenaline may result from a defect in Ca2+ mobilisation to the cytosol. The observed selectivity in the agonists affected may indicate that the stimulus-response coupling pathways converge at the level of an increase in cytosolic Ca2+ concentration.

Stimulation Of Human Platelets By Lysophosphatidic Acids

1981 ◽  
Author(s):  
D E MacIntyre
Keyword(s):  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Lysosomal Hydrolases ◽  
Stimulus Response ◽  
Ca Antagonist ◽  
Intracellular Ca ◽  
Arachidonate Metabolites ◽  
Irreversible Aggregation ◽  
Subsequent Addition

Production of lysophosphatidic acids (LPA) by “activated” cells may be important in stimulus-response coupling. Using human citrated platelet rich plasma (PRP) we examined the effects of Oleoyl (0), Palmitoyl (P) and Decanoyl (D) LPAS on platelet function. DLPA (≤300 μM) did not affect platelet function, and OLPA and PLPA (≤200 μM) did not inhibit uptake of 3H-5HT (0.3 μM). However OLPA and PLPA (1-30 μM) induced reversable aggregation in the absence of 5HT release (primary aggregation), and higher concentrations (≤300 μM) induced irreversible aggregation and TxB production and release of ≤79% of 5HT, 89% of βTG and ≤73% of β -N-acetyl glucosaminidase that was released by thrombin (1U/ml). LPA-induced release of platelet granule constituents was associated with <5% release of cytoplasmic markers LDH or 3H-adenine. OLPA or PLPA (300 μM) suppressed the elevation of platelet cyclic AMP induced by PGE1. Primary and secondary aggregation induced by LPA were suppressed by PGE1 (1 μ M) and the intracellular Ca antagonist, TMB-8 (200 μM). The Ca transport inhibitor verapamil (100 μM) was ineffective. Indomethacin (30 μM) and the ADP antagonist, β,γ-methylene-ATP (30 μM) inhibited only secondary aggregation. PRP exposed to OLPA or PLPA (30 μM) for greater than two minutes at 37°C failed to respond to subsequent addition of LPA but showed augmented responses to ADP, U 46619, vasopressin and 5HT. OLPA and PLPA resemble the more powerful platelet agonists (e.g., collagen, thrombin) in that they induce secretion of βTG, 5HT and lysosomal hydrolases and cause aggregation that is independent of ADP, 5HT or arachidonate metabolites. Endogenous LPA may function as a mediator of platelet aggregation and degranulation. Alternatively LPA may serve as a mimic of related platelet agonists (acetyl- glyceryl-ether-phosphorylcholine [AGEPC], or PAF-acether).

Inhibition and potentiation of platelet function by lysolecithin

Blood ◽  
1977 ◽  
Vol 49 (1) ◽  
pp. 101-112 ◽  
Author(s):  
JH Joist ◽  
G Dolezel ◽  
MP Cucuianu ◽  
EE Nishizawa ◽  
JF Mustard
Keyword(s):  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Membrane Damage ◽  
Adenosine Diphosphate ◽  
Lactic Dehydrogenase ◽  
Inhibitory Effect ◽  
Human Platelets ◽  
Serotonin Release ◽  
Prolonged Incubation ◽  
Induced Aggregation

Abstract The effects of lysolecithin (LPC) on aggregation, serotonin release, shape, and lysis of rabbit, pig, or human platelets in platelet-rich plasma (PRP) or Tyrode albumin solution were examined during prolonged incubation. LPC added to citrated or heparinized PRP from humans or rabbits at a final concentration above 100 muM caused instantaneous inhibition of platelet aggregation induced by adenosine diphosphate (ADP), epinephrine (human PRP only), collagen, or thrombin. The inhibitory effect of LPC was found to be partially reversible over a period of 60–90 min. LPC at final concentrations above 30 muM also caused inhibition of ADP-, collagen-, and thrombin-induced aggregation and collagen- and thrombin-induced release of serotonin in suspensions of rabbit, pig, or human platelets. With washed platelets, the inhibitory effect not only rapidly disappeared but was followed by transient potentiation of aggregation and serotonin release. This potentiating effect of LPC was most pronounced when thrombin was used as stimulus. Both inhibition and potentiation were observed at concentrations of LPC that did not cause a significant change in platelet shape or loss from platelets of lactic dehydrogenase. Inhibition and potentiation were also observed when platelets were added to suspending medium containing LPC, although considerably higher concentrations of LPC were required under these conditions. Potentiation was not observed when LPC was added to citrated or heparinized rabbit or human PRP or to washed rabbit platelets suspended in a medium containing 4% bovine serum albumin. It seemed likely that some or all of the observed effects of LPC on platelet function were due to structural modification of the platelet membrane insufficient to result in gross membrane damage or platelet lysis. In addition, the results of experiments using 14C-LPC seemed to indicate that the observed potentiating effect of LPC on platelet function may be related to its rapid uptake and metabolism by the platelets.

scholarly journals Part of the activating cross-linked immunoglobulin G is internalized by human platelets to sites not accessible for enzymatic digestion

Blood ◽  
1986 ◽  
Vol 67 (1) ◽  
pp. 12-18 ◽  
Author(s):  
MO Spycher ◽  
UE Nydegger
Keyword(s):  
Immunoglobulin G ◽  
Prostaglandin E1 ◽  
Cytochalasin B ◽  
Enzymatic Digestion ◽  
Human Platelets ◽  
Serotonin Release ◽  
Antimycin A ◽  
Energy Dependent ◽  
Increased Susceptibility ◽  
Pronase Treatment

Abstract The differential uptake of tritium-labeled immunoglobulin G (IgG) cross- linked with bisdiazonium-benzidine (BDB) (3H-BDB-IgG) by washed, pooled human platelets to sites inaccessible to pronase digestion was tested. Up to 52% of the 3H-BDB-IgG associated with platelets at 37 degrees C resisted pronase treatment, whereas only 23% of the cross-linked IgG associated with platelets at 4 degrees C, or at 37 degrees C but in the presence of deoxyglucose/antimycin A, remained refractory to pronase. This effect was not due to platelet agglutination. Pronase resistance reached a maximum after a 60-minute incubation period at 37 degrees C. With increasing 3H-BDB-IgG input, both the total cross-linked IgG associated with platelets and the fraction resistant to pronase digestion approached saturation at 4 degrees C, but not at 37 degrees C. The proportion of 3H-BDB-IgG bound to platelets at 4 degrees C that was resistant to pronase treatment increased by 13% within five minutes of warming the platelets to 37 degrees C. Pretreatment of platelets with 10 mmol/L acetylsalicylic acid (or 10 mumol/L prostaglandin E1) prior to the addition of 3H-BDB-IgG led to a 74% (95%) inhibition of the 3H-BDB-IgG-induced 14C-serotonin release, but to only a 44% (49%) inhibition of pronase-digestible bound ligand. In contrast, pretreatment with 10 mumol/L cytochalasin B led to a mere 17% reduction of 14C-serotonin release, whereas acquisition of resistance to pronase digestion by the bound 3H-BDB-IgG was inhibited by 90%. Incubation of platelets at 37 degrees C with 3H-BDB-IgG and removal of unbound material prior to the addition of prostaglandin E1 or deoxyglucose/antimycin A had little effect on the susceptibility of platelet-associated 3H-BDB-IgG to pronase, whereas the addition of cytochalasin B to 3H-BDB-IgG-treated platelets resulted in greatly increased susceptibility of the platelet-associated ligand to pronase. Thus, after binding, 3H-BDB-IgG becomes transferred in an energy- dependent process to pronase-resistant cellular sites, most likely to the open canalicular system.

Effects of Lead Acetate on Platelet Aggregation, Ultrastructure and Serotonin Release

1971 ◽  
Vol 26 (03) ◽  
pp. 455-466 ◽  
Author(s):  
R. B Davis ◽  
G. C Holtz
Keyword(s):  
Platelet Aggregation ◽  
Platelet Function ◽  
Lead Acetate ◽  
Platelet Rich Plasma ◽  
Adenosine Diphosphate ◽  
Blood Platelet ◽  
Human Platelets ◽  
Serotonin Release ◽  
Aggregation Of Platelets

SummaryThe effects of lead on blood platelet function and ultrastructure have been investigated. Lead acetate was injected intravenously in 27 rats and was added to rat and human platelet rich plasma in vitro. In vitro studies showed that concentrations of 2.5 × 10-3 M lead acetate reduced or blocked aggregation of rat and human platelets by adenosine diphosphate, collagen, and thrombin. Radioactive serotonin release from human platelets was inhibited by 10-4 M lead acetate. One hour after the injection of lead, platelet aggregation by thrombin was reduced, but platelet aggregation by adenosine diphosphate and collagen showed little change. Three days after lead, aggregation of platelets by collagen and thrombin was blocked and aggregation by adenosine diphosphate reduced. Thrombocytopenia was present 4 days after intravenous lead acetate. Electron micrographs of platelets showed that the mean number of mitochondria per platelet was increased, whereas alpha granules were reduced. Dense bodies were not significantly changed. Lead acetate affects platelet function in concentrations reported in human bone marrow in lead poisoning, and may relate to the binding of free sulfhydryl groups by lead.

scholarly journals Effect of anti-P1A1 antibody on human platelets. I. The role of complement

Blood ◽  
1979 ◽  
Vol 53 (4) ◽  
pp. 567-577 ◽  
Author(s):  
DB Cines ◽  
AD Schreiber
Keyword(s):  
Platelet Aggregation ◽  
Complement Activation ◽  
Platelet Rich Plasma ◽  
Plasma Concentrations ◽  
Human Platelets ◽  
Serotonin Release ◽  
Buffer System ◽  
Induce Platelet Aggregation ◽  
Platelet Surface ◽  
Release Reaction

Abstract We studied the interaction of complement with human platelets. Complement was activated by IgG anti-P1A1 antibody obtained from 3 patients with the post-transfusion purpura syndrome. We used a heparin- plasma buffer system that permits complement activation and also preserves platelet function. With this system complement activation was efficient, and platelet immune alteration was extensive. Anti-P1A1 antibody was effective only in the presence of complement, in which case both platelet lysis and serotonin release (release reaction) in the absence of lysis were observed. Platelet lysis, as assessed by 51Cr loss, required 10-fold more antibody than was necessary to induce platelet aggregation and release of 14C-serotonin. This platelet release reaction required an intact classic complement sequence through C6. The extent of platelet serotonin release parallelled the depletion of C1 and C4 from platelet-rich plasma. Concentrations of antibody insufficient to induce platelet aggregation and serotonin release could still activate C1 and deposit increased C3 on the platelet surface. These studies demonstrated that complement activation by anti-P1A1 antibody can alter human platelets in a nonlytic system. Several phases of complement-mediated human platelet alteration are possible, depending on the concentration of anti-P1A1 antibody.

Galectin-1 Purified from Human Platelets.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3936-3936
Author(s):  
Nilda Ester Fink ◽  
Mariana M. Gonzalez
Keyword(s):  
Platelet Function ◽  
Platelet Rich Plasma ◽  
Consensus Sequence ◽  
Allergic Inflammation ◽  
Human Platelets ◽  
Binding Activity ◽  
Size Exclusion ◽  
Carbohydrate Binding ◽  
Biological Functions ◽  
Negative Controls

Abstract Galectins are a family of lectins which exhibit β-galactoside-binding activity. They are Ca++-independent and have a common consensus sequence in the carbohydrate binding domain. Fourteen mammalian members of this family have been sequenced and well-characterised in different species, although galectins-1 and -3 have been the most thoroughly studied. They have biological functions in the regulation of the immune system such as allergic inflammation and host defence (activation of mast cells, neutrophils and eosinophils, stimulation of interleukins production and in the generation of oxidizing radicals), but scarse information is avalaible on biological functions in platelet function and hemostasia. The objective of this work was to detect and purified galectins from human platelets. Platelet-rich plasma obtained from blood bank, with negative serology for HIV, HBsAg and HVC, was filtered by a Pall Purecell PL filter (USA) to produce leucoreduction. Later, platelets were centrifuged and the pellet was homogenized in MEPBS (mercaptoethanol-EDTA-phosphate buffer saline)-200 mM lactose. The supernatant was treated by anion-exchange and affinity chromatography (lactose-agarose) followed by size exclusion in FPLC. We determined that an amount of 6-10 fg was present in a single platelet. The molecule was a dimer with a subunit of 14 kDa. Purified protein was isolated by PAGE-SDS and electroblotted onto nitrocellulose sheets. Identity was revealed employing polyclonal and monoclonal anti-galectin antibodies. Positive and negative controls were running simultaneously. Amino acid sequencing of galectin peptides performed indicated that it was a galectin-1. We conclude that galectin-1 is present in human platelets. Potential roles of galectin-1 in platelet function and hemostasia are under study.

Proteolytic Inhibitors, Contact and Other Variables in the Release Reaction of Human Platelets

1972 ◽  
Vol 28 (03) ◽  
pp. 393-407 ◽  
Author(s):  
Marjorie B. Zucker
Keyword(s):  
Cyclic Amp ◽  
Prostaglandin E1 ◽  
Platelet Rich Plasma ◽  
Human Platelets ◽  
Ph Changes ◽  
Release Reaction ◽  
Platelet Shape

SummaryPlatelet-rich plasma (PRP) containing platelets labelled with 14C-serotonin was used to characterize the release reaction. Heparin promotes release, and the reduced release response to epinephrine observed in heparinized compared to citrated PRP is probably due to the earlier reaction. The release reaction can occur in citrated PRP at pH 7.0, is marked between pH 7.2 and 7.6, and decreases above pH 8.0. It is retained better when PRP is stored below pH 7.7. Adenosine, prostaglandin E1, and theophylline inhibit both aggregation and release, probably because they elevate cyclic AMP. D- and L-tosyl-phenylalanine chloromethylketone (TPCK) also inhibit both aggregation and release at a concentration of 0.1 mM whereas 0.1 mM D- and l-L-chloro-2-tosylamido-7-amino-2-heptanone (TLCK) and 5 mM diisopropylfluoro-phosphate (DFP), like aspirin, inhibit only release. Colchicine (0.1 mM) alters platelet shape but does not affect release or aggregation. Centrifugation of PRP at 37° C causes release which responds to inhibitors and pH changes in a manner similar to release induced by aggregation with ADP or epinephrine. Release occurs in thromb-asthenic platelets centrifuged at 37° C and is increased by epinephrine. Release of ATP and ADP correlates significantly with release of 14C-serotonin. Thrombin plus CaCl2 causes release of β-glucuronidase but not of zinc.

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