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.

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 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.

The Effects Of Chymotrypsin And Of ADP On The Binding Site For Bovine Factor VIII On Human Platelets

1981 ◽  
Author(s):  
Edward P Kirby ◽  
David C B Mills
Keyword(s):  
Factor Viii ◽  
Binding Site ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Shape Change ◽  
Human Platelets ◽  
Simple Process ◽  
Affecting Factor ◽  
Platelet Binding ◽  
Bovine Factor

The aggregation of human platelets by bovine Factor VIII (Platelet Agglutinating Factor-PAF) is inhibited by exposure of the cells to ADP or Chymotrypsin. We have investigated the mechanism of these effects using washed platelets. The washing procedure was modified from the method of Mustard et al. (Brit. J. Haematol. 22:193, 1972), omitting heparin and using a protein-free Tyrode’s solution for the final resuspension. The washed platelets were stable and responded to ADP (0.1-1 μM) with a shape change and, if fibrinogen was added, with aggregation. Bovine Factor VIII was purified to >90% homogeneity and was labeled with 125I (approx. 1 atom/subunit) by the IodoGen procedure, with no loss of activity. Aggregation was measured in the aggregometer in the presence of 7 mM EDTA. Binding was measured after incubation of labeled Factor VIII with washed platelets in the presence of 7 mM EDTA for 5 min at 37° without stirring.Treatment of washed platelets with Chymotrypsin progressively destroyed their ability to bind Factor VIII and to be agglutinated by it. Responsiveness to Factor VIII disappeared before any alteration was detected in the ability of platelets to undergo ADP-induced shape change. Treatment of platelets with ADP, however, inhibited agglutination induced by Factor VIII without affecting the binding of Factor VIII to the platelets. Agglutination by wheat germ agglutinin or phytohemagglutinin was not inhibited by ADP treatment. We conclude that Chymotrypsin probably inhibits Factor VIII- induced agglutination by destroying the platelet binding site for Factor VIII, but that ADP must act at a point distal to Factor VIII binding. Agglutination of metabolically intact platelets by Factor VIII may not be a simple process, because ADP can specifically inhibit it without affecting Factor VIII binding or aggregation of the platelets by lectins.

Effects of Bupranolol, a New β-Blocker, on Platelet Functions of Rabbit and Human in Vitro

1976 ◽  
Vol 36 (02) ◽  
pp. 376-387 ◽  
Author(s):  
Teruhiko Umetsu ◽  
Kazuko Sanai ◽  
Tadakatsu Kato
Keyword(s):  
Platelet Aggregation ◽  
Platelet Adhesion ◽  
Human Platelets ◽  
Rabbit Platelet ◽  
Rabbit Platelets ◽  
Β Blocker ◽  
Platelet Aggregates ◽  
Induced Aggregation ◽  
Platelet Functions

SummaryThe effects of bupranolol, a new β-blocker, on platelet functions were investigated in vitro in rabbits and humans as compared with propranolol, a well-known β-blocker. At first, the effect of adrenaline on ADP-induced rabbit platelet aggregation was studied because adrenaline alone induces little or no aggregation of rabbit platelets. Enhancement of ADP-induced rabbit platelet aggregation by adrenaline was confirmed, as previously reported by Sinakos and Caen (1967). In addition the degree of the enhancement was proved to be markedly affected by the concentration of ADP and to increase with decreasing concentration of ADP, although the maximum aggregation (percent) was decreased.Bupranolol and propranolol inhibited the (adrenaline-ADP-)induced aggregation of rabbit platelets, bupranolol being approximately 2.4–3.2 times as effective as propranolol. Bupranolol stimulated the disaggregation of platelet aggregates induced by a combination of adrenaline and ADP, but propranolol did not. Platelet adhesion in rabbit was also inhibited by the β-blockers and bupranolol was more active than propranolol. With human platelets, aggregation induced by adrenaline was inhibited by bupranolol about 2.8–3.3 times as effectively as propranolol.From these findings. We would suggest that bupranolol might be useful for prevention or treatment of thrombosis.

Reaction of Acetaldehyde with Human Platelets

1992 ◽  
Vol 67 (01) ◽  
pp. 126-130 ◽  
Author(s):  
Olivier Spertini ◽  
Jacques Hauert ◽  
Fedor Bachmann
Keyword(s):  
Platelet Aggregation ◽  
Inhibitory Action ◽  
Ex Vivo ◽  
Platelet Rich Plasma ◽  
Shape Change ◽  
Reaction Medium ◽  
Human Platelets ◽  
Membrane Glycoproteins ◽  
Neutral Ph

SummaryPlatelet function defects observed in chronic alcoholics are not wholly explained by the inhibitory action of ethanol on platelet aggregation; they are not completely reproduced either in vivo by short-term ethanol perfusion into volunteers or in vitro by the addition of ethanol to platelet-rich plasma. As acetaldehyde (AcH) binds to many proteins and impairs cellular activities, we investigated the effect of this early degradation product of ethanol on platelets. AcH formed adducts with human platelets at neutral pH at 37° C which were stable to extensive washing, trichloracetic acid hydrolysis and heating at 100° C, and were not reduced by sodium borohydride. The amount of platelet adducts formed was a function of the incubation time and of the concentration of AcH in the reaction medium. At low AcH concentrations (<0.2 mM), platelet bound AcH was directly proportional to the concentration of AcH in the reaction medium. At higher concentrations (≥0.2 mM), AcH uptake by platelets tended to reach a plateau. The amount of adducts was also proportional to the number of exposures of platelets to pulses of 20 pM AcH.AcH adducts formation severely impaired platelet aggregation and shape change induced by ADP, collagen and thrombin. A positive correlation was established between platelet-bound AcH and inhibition of aggregation.SDS-PAGE analysis of AcH adducts at neutral pH demonstrated the binding of [14C]acetaldehyde to many platelet proteins. AcH adduct formation with membrane glycoproteins, cytoskeleton and enzymes might interfere with several steps of platelet activation and impair platelet aggregation.This in vitro study shows that AcH has a major inhibitory action on platelet aggregation and may account for the prolonged ex vivo inhibition of aggregation observed in chronic alcoholics even in the absence of alcoholemia.

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 Pathways of Thrombin-Induced Aggregation and Release with Human and Rabbit Platelets

1977 ◽  
Author(s):  
R.L. Kinlough-Rathbone ◽  
D.W. Perry ◽  
M.A. Packham ◽  
J.F. Mustard
Keyword(s):  
Platelet Aggregation ◽  
Direct Effect ◽  
Thromboxane A2 ◽  
Human Platelets ◽  
The Third ◽  
Rabbit Platelets ◽  
Induced Aggregation

There are at least 3 mechanisms involved in thrombin-induced aggregation and release: (1) released ADP, (2) formation of thromboxane A2 and (3) a third mechanism(s). We have examined whether the third pathway is due to formation or release of a substance from platelets which affects other platelets. Washed human platelets were exposed to thrombin (2.5 u/ml) for 15 min at 37°C in the presence of indomethacin to block thromboxane A2 formation. Platelets were removed by centrifugation and the thrombin neutralized with hirudin or DFP. Addition of the superna te to washed human platelets prelabeled with 14C-serotonin caused platelet aggregation but release did not occur. Treatment of the supernate with apyrase, CP/CPK or dialysis abolished aggregation, indicating that the material was ADP. Thus, the mechanism by which thrombin induces aggregation and release with human platelets in the presence of agents which destroy ADP and block the formation of thromboxane A2 is a direct effect of thrombin on platelets and does not involve a substance freed from platelets. In contrast, when washed rabbit platelets were treated with thrombin in the presence of indomethacin and the released ADP was removed, material remained in the supernate which caused aggregation and release from washed rabbit platelets but was without effect on washed human platelets. The activity of this material (MW > 10,000) was not abolished by dialysis or boiling. Therefore rabbit platelets differ from human platelets because they have a mechanism in addition to released ADP, thromboxane A2 and the direct effect of thrombin on platelets that can cause aggregation and release.

MECHANISMS OF PLATELET AGGREGATION BY ACIDIC MUCOPOLYSACCHARIDE EXTRACTED FROM STICHOPUS JAPONICUS SELENKA IN HUMANS AND RABBITS

1987 ◽  
Author(s):  
J Z Li ◽  
E C-Y Lian
Keyword(s):  
Platelet Aggregation ◽  
Ammonium Sulfate ◽  
Human Platelets ◽  
Platelet Inhibitors ◽  
Rabbit Plasma ◽  
Human Fibrinogen ◽  
Stichopus Japonicus ◽  
Saturated Ammonium Sulfate ◽  
Rabbit Platelets ◽  
Induced Aggregation

It has been reported that acidic mucopolysaccharide extracted from sea cucumber (Stichopus japonicus selenka) (SJAMP) induced the aggregation of human and animal platelets by an unknown mechanism, using platelet-rich plasma (prp) and washed human and rabbit platelets we studied the effects of storage, platelet inhibitors, and various plasmas and their fractions on SJAMP-induced platelet aggregation. we found that the lowest concentrations of SJAMP required for aggregation of human and rabbit platelets were 0.4 and 2 ug/ml respectively. The reactivity of human platelets to SJAMP decreased with time after drawing of blood; rabbit platelets did not show this phenomenon. Platelet inhibitors such as aspirin, indomethacin, apyrase, antimycin, 2-deoxy-D-glucose, and EDTA inhibited by 50 to 100% the aggregation of human platelets induced by SJAMP; but these inhibitors had no effect on SJAMP-induced aggregation of rabbit platelets. Washed human and rabbit platelets were not aggregated by SJAMP. The aggregation of washed human platelets by SJAMP was restored completely by human or rabbit plasma, by human fibrinogen, or by 0 to 30% saturated ammonium sulfate fraction but not by serum. The aggregation of rabbit platelets by SJAMP could only be restored by rabbit plasma or serum, or by 50 to 60% saturated ammonium sulfate fraction. The data indicate that the mechanisms of aggregation of human and rabbit platelets by SJAMP are different. THe SJAMP-induced human platelet aggregation is dependent upon metabolism, release of ADP and the cyclooxygenase pathway requiring fibrinogen and Ca++. The aggregation of rabbit platelets induced by SJAMP is independent of metabolism, release of ADP and cyclooxygenase pathway, and does not require fibrinogen and Ca++, but needs certain protein(s) in the 50 to 60% saturated ammonium sulfate fraction of rabbit plasma.

scholarly journals Factor VIII-induced superaggregation of human platelets

Blood ◽  
1982 ◽  
Vol 60 (6) ◽  
pp. 1359-1369 ◽  
Author(s):  
EP Kirby ◽  
DC Mills ◽  
H Holmsen ◽  
M Russo
Keyword(s):  
Factor Viii ◽  
Cytochalasin B ◽  
Dextran Sulfate ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Ionophore A23187 ◽  
High Concentrations ◽  
Induced Aggregation ◽  
Very High ◽  
Bovine Factor

Abstract High concentrations of bovine factor VIII cause clumping of platelets into a few very large aggregates. This response is termed superaggregation. It is distinct from factor-VIII-induced agglutination but is also independent of both extracellular calcium ions and platelet energy metabolism. Neither agglutinating lectins nor aggregating agents, including thrombin, ADP, the ionophore A23187, and U46619, a prostaglandin analog, can induce superaggregation, even at very high concentrations. Washed platelets undergo superaggregation, and superaggregation does not increase the amounts of fibrinogen or albumin trapped by agglutinated platelets. It is not inhibited by membrane- stabilizing drugs or by colchicine or cytochalasin-B. Formaldehyde and glutaraldehyde prevent superaggregation without affecting the binding of radiolabeled factor VIII to the platelets. Superaggregated platelets are separated by approximately 50 nm and are not shape-changed or degranulated. In adenosine diphosphate (ADP) induced aggregation, the platelets are distorted and only 30 nm apart. Superaggregation is reversed by dextran sulfate, and the dispersed platelets are still able to respond to ADP. Our observations are consistent with the binding of high molecular weight multimers of bovine factor VIII to more than one receptor on each platelet, with superaggregation occurring through recruitment of additional receptors. This process may be interrupted by protein crosslinking reagents, such as formaldehyde and glutaraldehyde.

Studies on the Shape Change in Rabbit Platelets Induced by Adenosine Diphosphate or Several Metabolic Inhibitors

1974 ◽  
Vol 31 (01) ◽  
pp. 179-186
Author(s):  
Norio Kobayashi ◽  
Tadashi Maekawa
Keyword(s):  
Platelet Aggregation ◽  
Shape Change ◽  
Adenosine Diphosphate ◽  
Metabolic Inhibitors ◽  
Distilled Water ◽  
Rabbit Platelets

Summary1. The shape change of platelet was induced in vitro by an addition of ADP, NEM, KCN or distilled water. The change induced by ADP occurred very rapidly.2. Among these reagents, only ADP induced the platelet aggregation.3. When ADP was added before the completion of the shape change by NEM, the shape change by ADP took place, while both ADP and NEM were added simultaneously, the pattern of the shape change was similar to that of ADP alone.4. The shape change of platelet by ADP was inhibited by the previous addition of adenosine, which did not affect the shape change induced by NEM.5. Correlation of the shape change of platelets to their aggregation was discussed.

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