Physiological Effects of Nonimmune Platelet Associated Immunoglobulin G

1981 ◽  
Vol 45 (01) ◽  
pp. 027-033 ◽  
Author(s):  
K Sugiura ◽  
M Steiner ◽  
M Baldini
Keyword(s):  
Shape Change ◽  
Fluorescein Isothiocyanate ◽  
Recovery Phase ◽  
Human Platelets ◽  
Serotonin Release ◽  
Platelet Volume ◽  
Igg Antibody ◽  
Heterologous Antiserum ◽  
Igg Binding ◽  
Series Of Experiments

SummaryThe function of nonimmune IgG associated with platelets is unknown. In a series of experiments we have investigated this problem, relating amount of platelet-associated IgG (PAIgG) to platelet volume, serotonin release, adherence of platelets to monocytes and platelet senescence. Most of these studies were performed with human platelets. Platelets freed of preexisting PAIgG by incubation at 22° C were incubated with IgG in a series of concentrations ranging from 0.4 — 27.0 X10-6 M. The IgG preparations used were demonstrably free of aggregated forms of the protein. The amount of PAIgG bound to platelets was determined by the use of fluorescein isothiocyanate-conjugated anti-IgG antibody (F-anti-IgG antibody) which was quantified in a fluorospectrophotometer. Newly bound IgG was assayed similarly by the use of F-IgG. A dose-dependent increase in platelet volume was associated with the binding of nonimmune IgG by platelets. The process which leveled off at an IgG concentration of 1.2 —1.5 X10-5 M was almost fully reversible and was not due to platelet shape change or aggregation. Release of serotonin from IgG-treated platelets was relatively small but to the extent that it occurred was positively related to the IgG concentration to which platelets were exposed. Adherence to autologous monocytes studied quantitatively by the use of formaldehyde-fixed cells was also positively related to the amount of IgG on the platelets. Normal or IgG-defident serum had a potent inhibitory (noncompetitive) action on the binding of F-IgG and F-anti-human IgG antibody to human platelets. Cohorts of platelets prepared in rabbits during the recovery phase of immunological thrombocytopenia induced by injection of heterologous antiserum, showed an age-dependent increase of PAIgG and of IgG binding. These results suggest that PAIgG plays a role in the clearance of senescent platelets.

scholarly journals Acquired IgG antibody occurring in a thrombasthenic patient: its effect on human platelet function

Blood ◽  
1978 ◽  
Vol 51 (6) ◽  
pp. 1065-1071 ◽  
Author(s):  
S Levy-Toledano ◽  
G Tobelem ◽  
C Legrand ◽  
R Bredoux ◽  
L Degos ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Shape Change ◽  
Antigenic Site ◽  
Human Platelets ◽  
Clot Retraction ◽  
Igg Antibody ◽  
Normal Human ◽  
Induced Aggregation ◽  
Bovine Factor

Abstract In subagglutinating amounts, an IgG antibody isolated from the plasma of a polytransfused thrombasthenic patient (L) inhibited ADP-, epinephrine-, collagen-, and thrombin-induced aggregation of normal human platelets. The inhibition of ADP-induced aggregation was strongly diminished following the prior incubation of the antibody with control human platelet stroma but not with the stroma prepared from the platelets of two different thrombasthenic patients. The IgG(L) did not affect the binding of 14C-ADP to control human platelet membranes and did not inhibit the ADP-induced shape change. Bovine factor VIIIVWF- induced agglutination and ristocetin-induced aggregation of control human platelets were not inhibited in the presence of the antibody. The IgG(L) strongly inhibited ADP-induced retraction of reptilase clot and thrombin-induced clot retraction. This antibody therefore induced a thrombasthenialike state in normal human platelets, suggesting that the antigenic site recognized by the antibody plays a central role in the later stages of the mechanism of platelet aggregation induced by physiologic aggregation-inducing agents.

scholarly journals Effects of Lectins on Blood Platelets from Various Species

1977 ◽  
Author(s):  
O. Tangen ◽  
B. Karlstam ◽  
S. Bygdeman
Keyword(s):  
Shape Change ◽  
Blood Platelets ◽  
Human Platelets ◽  
Serotonin Release ◽  
Variable Degree ◽  
Con A ◽  
Platelet Release ◽  
Induced Aggregation ◽  
Aggregation Of Platelets ◽  
Platelet Shape

Earlier it has been shown that different lectins induce a variable degree of aggregation of platelets. The present study confirmed previous data and demonstrated that wheat germ agglutinin (WGA) was very active, 1eucoagglutinin had about a tenth of the activity of WGA on a concentration basis, and Con A had a weak aggregating effect on human gel filtered platelets (GFP). Soy bean lectin did not aggregate human GFP.The fact that adenosine inhibited WGA- and leucoagglutinin-induced aggregation that WGA and Con A caused serotonin release, and that the aggregation- curves indicated platelet shape change are indications that the lectins influenced glycosyl moieties involving one or more molecules relevant to release and aggregation reaction.GFP were markedly more responsive to the lectins than platelets in plasma, probably due to interfering glycosyl groups amongst the plasma constituents.Platelets from man, rabbit, rat, cow and pig reacted differently towards the lectins, human platelets being the most reactive and bovine and porcine platelets being almost unreactive. These results pose intriguing questions regarding the glycosyl content of platelet membranes in different species and their relation to platelet release and aggregation.

An atypical IgM class platelet cold agglutinin induces GPVI-dependent aggregation of human platelets

2015 ◽  
Vol 114 (08) ◽  
pp. 313-324 ◽  
Author(s):  
Isabel Sánchez Guiu ◽  
Irene Martínez-Martinez ◽  
Constantino Martínez ◽  
José Navarro-Fernandez ◽  
Faustino Garcia-Candel ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Human Platelets ◽  
Serotonin Release ◽  
Platelet Glycoprotein ◽  
Causative Role ◽  
Temperature Dependent ◽  
Activation Markers

SummaryPlatelet cold agglutinins (PCA) cause pseudothrombocytopenia, spurious thrombocytopenia due to ex vivo platelet clumping, complicating clinical diagnosis, but mechanisms and consequences of PCA are not well defined. Here, we characterised an atypical immunoglobulin (Ig)M PCA in a 37-year-old woman with lifelong bleeding and chronic moderate thrombocytopenia, that induces activation and aggregation of autologous or allogeneic platelets via interaction with platelet glycoprotein (GP)VI. Patient temperature-dependent pseudothrombocytopenia was EDTA-independent, but was prevented by integrin αIIbβ3 blockade. Unstimulated patient platelets revealed elevated levels of bound IgM, increased expression of activation markers (P-selectin and CD63), low GPVI levels and abnormally high thromboxane (TX)A2 production. Patient serum induced temperature- and αIIbβ3-dependent decrease of platelet count in allogeneic donorcitrated platelet-rich plasma (PRP), but not in PRP from Glanzmann’s thrombasthenia or afibrinogenaemia patients. In allogeneic platelets, patient plasma induced shape change, P-selectin and CD63 expression, 14C-serotonin release, and TXA2 production. Activation was not inhibited by aspirin, cangrelor or blocking anti-Fc receptor (FcγRIIA) antibody, but was abrogated by inhibitors of Src and Syk, and by a soluble GPVI-Fc fusion protein. GPVI-deficient platelets were not activated by patient plasma. These data provide the first evidence for an IgM PCA causing platelet activation/aggregation via GPVI. The PCA activity persisted over a five-year follow-up period, supporting a causative role in patient chronic thrombocytopenia and bleeding.

scholarly journals Acquired IgG antibody occurring in a thrombasthenic patient: its effect on human platelet function

Blood ◽  
1978 ◽  
Vol 51 (6) ◽  
pp. 1065-1071
Author(s):  
S Levy-Toledano ◽  
G Tobelem ◽  
C Legrand ◽  
R Bredoux ◽  
L Degos ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Human Platelet ◽  
Shape Change ◽  
Antigenic Site ◽  
Human Platelets ◽  
Clot Retraction ◽  
Igg Antibody ◽  
Normal Human ◽  
Induced Aggregation ◽  
Bovine Factor

In subagglutinating amounts, an IgG antibody isolated from the plasma of a polytransfused thrombasthenic patient (L) inhibited ADP-, epinephrine-, collagen-, and thrombin-induced aggregation of normal human platelets. The inhibition of ADP-induced aggregation was strongly diminished following the prior incubation of the antibody with control human platelet stroma but not with the stroma prepared from the platelets of two different thrombasthenic patients. The IgG(L) did not affect the binding of 14C-ADP to control human platelet membranes and did not inhibit the ADP-induced shape change. Bovine factor VIIIVWF- induced agglutination and ristocetin-induced aggregation of control human platelets were not inhibited in the presence of the antibody. The IgG(L) strongly inhibited ADP-induced retraction of reptilase clot and thrombin-induced clot retraction. This antibody therefore induced a thrombasthenialike state in normal human platelets, suggesting that the antigenic site recognized by the antibody plays a central role in the later stages of the mechanism of platelet aggregation induced by physiologic aggregation-inducing agents.

IRREVERSIBLE BLOCKADE OF THE THROMBOXANE A2/PROSTAGLANDIN H2 RECEPTOR OF HUMAN PLATELETS BY AZIDO-BSP

1987 ◽  
Author(s):  
H Zehender ◽  
E C Witte ◽  
K Stegemeier ◽  
A Patscheke
Keyword(s):  
Shape Change ◽  
Thromboxane A2 ◽  
High Specificity ◽  
Short Wave ◽  
Human Platelets ◽  
Serotonin Release ◽  
Irreversible Inhibition ◽  
High Concentrations ◽  
Very High ◽  
Platelet Shape

Azido-BSP (4-[2-(4-azido-benzenesulphonylamino)-ethyl]phen-oxyacetic acid) is a photolabile derivative of the competitive thromboxane A2 /prostaglandin H2 (TXA2/PGH2) receptor antagonist sulotroban (=BM 13.177). If protected from short wave light, azido-BSP reversibly inhibited the platelet shape change induced by the PGH2 analogue U 46619 but notthe shape change induced by ADP or PAF. Schild analysis revealed an apparent KD=0.2 μM with washed platelets. The irreversible inhibition requiredirradiation of the platelet suspensionwith UVlight (254 nm) for 5 minutes in the presenceof azido-BSP. After this treatment,the platelets were washed twice and used forplatelet function tests. Treatment with 0.5 μM of azido-BSP suppressed the U 46619(10 μM)-induced (3H)serotonin release and 1 μM of azido-BSP was necessary to block the U 46619(2 μM)-inducedaggregation.The platelet shape change induced by U 46619 (0.01μM) was only partially inhibited, even at very high concentrations (50μM) of the antagonist.This suggests that a small portion of the TXA2/PGH2 receptors could not be blocked bythe photoaffinity treatment with azido-BSP. After treatment with 1 μM azido-BSP, the shape change stimulated by ADP or PAF was not reduced. This indicates a high specificity of thephotoaffinity ligand for the TXA2/PGH2 receptor. It is concluded that UV irradiation of azido-BSP generates anitrene intermediate that covalently links to the majority of the TXA2/PGH2 receptors. Azido-BSP provides a specific tool for tagging and subsequent purification of the TXA2/PGH2 receptor of platelets.(Supported by the Deutsche Forschungsgemeinschaft, Grant Pa263).

Specificity of an Acquired Antiplatelet Antibody Occuring in a Polytransfused Thrombasthenic Patient

1975 ◽  
Author(s):  
S. Levy-Toledano ◽  
R. Bredoux ◽  
F. Rendu ◽  
G. Tobelem ◽  
L. Degos ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Factor Viii ◽  
Complement Fixation ◽  
Shape Change ◽  
Human Platelets ◽  
Igg Antibody ◽  
Antiplatelet Antibody ◽  
Normal Individuals ◽  
Rabbit Platelets ◽  
Bovine Factor

An IgG antibody which developed in a polytransfused thrombasthenic patient reacted in complement fixation with platelets from 350 normal individuals but not with platelets from 8 other thrombasthenic patients. It agglutinates human platelets in PRP but not thrombasthenic platelets. This agglutination increased if the PRP was preincubated at 37°C or if the platelets were isolated before the addition of the antibody. Dog but not rabbit platelets are agglutinated by the patient plasma. Neither adenosine, nor PGE1 inhibit this agglutination which is slightly reduced by acetylsalicilic acid and disappears with EDTA and EGTA (3,8 mM).Its activity is reduced or abolished after incubation with control platelet membranes but not with those obtained fron) thrombasthenic or rabbit platelets.It does not inhibit the ADP-induced shape change of normal platelets, and it prevents all the ADP mediated platelet aggregations but, not those induced by bovine factor VIII and ristocetin.This antibody seemed to be directed against a molecule absent or structurally modified in thrombasthenic platelets which would be involved in platelet aggregation and more especially in ADP mediated platelet aggregation.

The Role Of Membrane-Bound Tubulin In Platelet Functions

1981 ◽  
Author(s):  
Y Ikeda ◽  
M Handa ◽  
Y Yoshii ◽  
M Imai ◽  
K Sugiura ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Shape Change ◽  
Human Platelets ◽  
Binding Activity ◽  
Serotonin Release ◽  
Platelet Membranes ◽  
Coomassie Blue ◽  
Tubulin Subunit ◽  
Membrane Bound

Evidence has been presented which suggests the existence of tubulin, subunit protein of microtubules, as an integral part of plasma membrane of certain cells. We have investigated whether tubulin is also a constituent of platelet plasma membrane or not, and, if so, what the functional significance is? Platelet membranes isolated by glycerol lysis technique according to the method of Barber and Jamieson retained colchicine-binding activity, 6.2 ± 1.4 n mol colchicine per 100 mg platelet membranes. Colchicine-binding activity of platelet membranes was not decreased after membranes were washed 3 times, indicating that colchicinebinding activity of membranes is not due to contamination of loosely bound cytoplasmic soluble tubulin. On SDS-poly- acrylamide gel electrophoresis, platelet membranes revealed Coomassie blue stained band of molecular weight 55,000, which comigrated with purified cytoplasmic tubulin isolated from human platelets by two successive cycles of temperature -dependent polymerization depolymerization as described previously(Ikeda & Steiner, J. Biol. Chem. 251:6135, 1976). Monospecific antibody against platelet tubulin was prepared in rabbits by injecting soluble tubulin at weekly intervals for 4 weeks. Platelets preincubated with anti-tubulin F(ab’)2 fragment showed reduced platelet aggregation and shape change induced by collagen, but not by ADP or epinephrine. Collagen-induced release of 14C-serotonin was also inhibited by anti-tubulin F(ab’)2 fragment while ADP- or epinephrine-induced serotonin release was not inhibited(collagen 2μg/ml:45.6% of control, ADP 10μM:92.0% of control, epinephrine 4μg/ml: 98.0% of control).Our results suggest that membrane-associated tubulin may play important roles in collagen-platelet interactions.

Role of Internalization in Platelet Activation Induced by Collagen Fibers – Differential Effects of Aspirin, Cytochalasin D, and Prostaglandin E1

1991 ◽  
Vol 66 (06) ◽  
pp. 708-714 ◽  
Author(s):  
Andreas Ruf ◽  
Heinrich Patscheke ◽  
Eberhard Morgenstern
Keyword(s):  
Prostaglandin E1 ◽  
Close Contact ◽  
Shape Change ◽  
Human Platelets ◽  
Serotonin Release ◽  
Collagen Fibers ◽  
Cytochalasin D ◽  
Collagen Membrane ◽  
Computer Assisted ◽  
Initial Contact

SummaryWashed human platelets were stimulated with fibrillar collagen and platelet aggregation was prevented by non-stirring conditions. In these samples, electron microscopy revealed three fractions of platelets: 1) a majority without contacts to the collagen fibers, 2) with focal contacts to collagen, and 3) a small fraction of platelets with internalized collagen. All platelets had undergone shape change, and exhibited an internal contraction and granule release. However, only those with internalized collagen were completely degranulated. The internalized collagen was found to be in close contact to the contractile sphere in the platelet center, as it was demonstrable with computer assisted 3-D reconstruction from serial sections. Aspirin inhibited neither the adhesion to collagen nor its internalization by internal contraction. Also it did not impair the shape change and degranulation in the platelet fractions that internalized collagen. However, aspirin blocked the shape change and internal contraction of the other platelets and inhibited the [3H]serotonin release. Cytochalasin D 0.1 uM also suppressed the internalization of collagen, the shape change, the formation of a contractile gel, the degranulation, and the [3H]serotonin release in all platelets, whereas the number of platelets that adhered to collagen remained unchanged. The same effects were produced by prostaglandin E1. If the platelets were stimulated with the TXA2 mimetic, U46619, cytochalasin D at 0.1 εM had no effect; but at 20 εM it strongly enhanced the degranulation and the [3H]serotonin release, although the platelets remained discoid. It is concluded that collagen triggers a focal activation of an adherent platelet at the site of its initial contact to collagen. This subthreshold activation proceeds to degranulation and TXA2 formation via a feedback cascade which involves internal contraction, internalization of collagen and multiplication of the collagen membrane contacts.

Effect of antiplatelet antibody on platelet shape change, volume, and morphology

1983 ◽  
Vol 244 (3) ◽  
pp. H357-H361 ◽  
Author(s):  
R. W. Colman ◽  
V. T. Nachmias ◽  
D. B. Cines ◽  
A. D. Schreiber
Keyword(s):  
Electron Microscopy ◽  
Morphological Changes ◽  
Shape Change ◽  
Human Platelets ◽  
Antibody Concentration ◽  
Platelet Volume ◽  
Antiplatelet Antibody ◽  
Specific Effects ◽  
Transmission Electron ◽  
Platelet Shape

We extended our studies of the effect of antibody on human platelets. Monomeric immunoglobulin G (IgG) (rabbit) antiplatelet antibody was interacted with human platelets in the absence of complement and the early morphological changes monitored. Platelet shape change, assessed by a rheooptical approach, was noted within 20 s and was proportional to antibody concentration. Antiplatelet antibody-induced shape change was also accompanied by a change in apparent platelet volume, as measured in the resistive particle counter. Scanning and transmission electron microscopy confirmed a disk-to-sphere transformation associated with the formation of bulbous, short surface projections or pseudopodia. In contrast, ADP-induced disk-to-sphere transformation was associated with the development of long, thin filopodia emanating from the platelet. These specific effects of antiplatelet antibody may result in altered platelet function.

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