Drug-Antibody-Platelet Interaction in Quinine- and Quinidine-induced Thrombocytopenia
01 Nov 1982-Journal of Clinical Investigation (American Society for Clinical Investigation)-Vol. 70, Iss: 5, pp 989-998
TL;DR: It is demonstrated that in quinine- and quinidine-induced thrombocytopenia, drug and antibody combine first in the soluble phase to form a complex, which then binds with high affinity to a receptor on the platelet surface (innocent bystander reaction), and that these antibodies are heterogeneous in respect to the amount of drug required to promote their binding to platelets, the number of platelet receptors they recognize, and their binding affinities.
Abstract: Binding of quinine- and quinidine-dependent antibodies to platelets was studied using an electroimmunoassay to measure platelet-bound IgG. Antibodies from four patients with drug-induced thrombocytopenia differed significantly in their interaction with platelets: association constants for binding to platelets at high drug concentrations ranged from 0.29 to 2.6 x 10(7) M(-1), the maximum number of antibody molecules bound ranged from 36,000 to 161,000/platelet, the amount of drug necessary to achieve half-maximum binding of antibodies to platelets ranged from 2 to 60 muM, and only one of the antibodies cross-reacted with the stereoisomer of the drug to which the patient was sensitized. Binding of the antibodies to platelets was enhanced at the highest achievable molar ratio of drug:antibody, 10,000:1, rather than being inhibited, as would be expected in a conventional, hapten-dependent reaction. The drug-antibody-platelet reaction was unaffected by Factor VIII/von Willebrand protein, nonspecifically aggregated IgG, or heat-labile complement components. After pretreatment with tritiated quinine, platelets retained several hundred thousand molecules of drug each, but failed to bind detectable amounts of antibody. However, platelets treated simultaneously with quinine-dependent antibody and tritiated quinine retained significantly more drug after repeated washes than platelets treated with drug and normal serum. These findings support the proposition that in quinine- and quinidine-induced thrombocytopenia, drug and antibody combine first in the soluble phase to form a complex, which then binds with high affinity to a receptor on the platelet surface (innocent bystander reaction), and demonstrate that these antibodies are heterogeneous in respect to the amount of drug required to promote their binding to platelets, the number of platelet receptors they recognize, and their binding affinities.
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References
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TL;DR: The original Lowry method of protein determination has been modified by the addition of sodium dodecyl sulfate in the alkali reagent and an increase in the amount of copper tartrate reagent to be used with membrane and lipoprotein preparations without prior solubilization or lipid extraction.
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TL;DR: It is concluded that, in PNH, platelets and granulocytes share the membrane defect characteristic of erythrocytes in this disorder, and these observations support the concept that PNH arises as the result of a somatic mutation in a primitive cell capable of differentiating into ery Throttleblast, myeloblast, and megakaryoblast lines.
Abstract: The tendency of platelets and leukocytes to lyse after their interaction with antibody and complement was studied by measuring the release of 51Cr from cells labeled with this isotope. Platelets from six patients with paroxysmal nocturnal hemoglobinuria (PNH) were 15-230 times more sensitive to antibodies and 10-32 times more sensitive to complement than normal platelets or platelets from patients with other types of thrombocytopenic or hemolytic disorders. Mixed white blood cell (WBC) preparations from patients with PNH were 3-20 times more sensitive to anti-WBC antibodies and 5-10 times more sensitive to C′ than were WBC preparations from normal subjects, but PNH lymphocytes showed normal immunologic reactivity. PNH platelets, like PNH erythrocytes, lysed more readily than normal platelets in acidified serum and in media of reduced ionic strength, but these characteristics were not demonstrable with PNH WBC's under the conditions of study. In PNH, platelets appear to comprise a single population with respect to their sensitivity to immune lysis, yet their survival time as measured with 51Cr falls within normal limits. PNH granulocytes likewise appear to consist of a single, uniformly sensitive population.
It is concluded that, in PNH, platelets and granulocytes share the membrane defect characteristic of erythrocytes in this disorder. These observations support the concept that PNH arises as the result of a somatic mutation in a primitive cell capable of differentiating into erythroblast, myeloblast, and megakaryoblast lines. PNH platelets or enzymatically treated normal platelets permit the detection of some types of platelet antibodies in dilutions up to 2000-fold greater than is possible with currently available methods, a finding suggesting that the immune lysis technique will prove useful for the study of platelet immunology.
198 citations
TL;DR: Purpura occurring during convalescence can best be explained on the assumption of an allergic basis, similar perhaps to that to which nephritis following streptococcal infections has been attributed.
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TL;DR: Plasma quinidine half-life values, determined by a relatively specific double extraction method in eight patients with poor renal function, eight with congestive heart failure, and nine controls were similar for all groups.
Abstract: Plasma quinidine half-life values, determined by a relatively specific double extraction method in eight patients with poor renal function, eight with congestive heart failure, and nine controls were similar for all groups. When quinidine was measured by a nonspecific fluorescent method, the half-life values calculated for the uremic patients were longer than those for the controls. The nonspecific method does not differentiate slow biotransformation of quinidine from normal biotransformation but slow excretion of metabolites. Steady-state plasma quinidine concentrations were measured in 14 patients treated for arrhythmias and 12 with congestive heart failure. Therapeutic effectiveness was associated with concentrations of 2.3 to 5.0 μg per milliliter and ineffectiveness with lower levels or complicating illnesses. The relation of dose to steady-state blood level was similar for the two groups. Quinidine elimination appears to be grossly normal in patients with congestive heart failure or poor re...
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TL;DR: Results of this study were consistent with the possibilities that the protein moiety of a haptenic antigen involved in development of an antibody which attaches to a cell is not necessarily a component of the cell, and that the cell reacts with the antibody by virtue of having a surface favorable for non-specific adsorption of certain haptene-antibody complexes.
Abstract: A steric and kinetic model for the sequence and mechanism of reactions leading to formation of a complex from an antibody, a haptene (quinidine), and a cell membrane (platelets), and to fixation of complement by the complex was deduced from the effects of varying the initial concentration of each component of the complex on the amount of complement fixed, from kinetic aspects of the sequential reactions, and from other chemical and physical properties of the various components involved. Theoretical results calculated using equations based on the model, which were derived by Dr. Terrell L. Hill, were similar in all respects to experimental results. Results of this study were consistent with the possibilities that the protein moiety of a haptenic antigen involved in development of an antibody which attaches to a cell is not necessarily a component of the cell, and that the cell reacts with the antibody by virtue of having a surface favorable for non-specific adsorption of certain haptene-antibody complexes.
153 citations