ABSTRACT
Acquired abnormalities of platelet aggregation have been reported with increasing frequency. We studied five patients (including two with systemic lupus erythematosus and one with compensated chronic idiopathic thrombocytopenic purpura) in whom platelet aggregation responses to collagen, epinephrine and ADP are impaired; in all cases, we found that levels of platelet-associated immunoglobulin G (IgG) were increased. In all five patients substances stored in platelet-dense granules (ATP, ADP, serotonin and calcium) were diminished. The content of the alpha-granule substance, beta-thromboglobulin, was also decreased in most cases, whereas the levels of two secretable acid hydrolase enzymes (beta-glucuronidase and beta-N-acetyl glucosaminidase) were within normal limits. These findings are similar to those observed in subtypes of congenital storage pool deficiency. However, in contrast to the congenital disorder, a membrane-bound (nonsecretable) acid phosphatase was also decreased in the patients with acquired storage pool deficiency. These findings suggest that impaired platelet aggregation on an acquired basis may, in some patients, be due to immune platelet damage resulting in a distinctive type of platelet storage pool deficiency.
Subject(s)
Hypergammaglobulinemia/blood , Immunoglobulin G , Platelet Aggregation , Thrombocythemia, Essential/blood , Adenosine Monophosphate/blood , Adenosine Monophosphate/deficiency , Adenosine Triphosphate/blood , Adenosine Triphosphate/deficiency , Blood Platelets/immunology , Calcium/blood , Calcium/deficiency , Humans , Lupus Erythematosus, Systemic/blood , Purpura, Thrombocytopenic/blood , Serotonin/blood , Serotonin/deficiency , beta-Thromboglobulin/deficiencySubject(s)
Blood Coagulation Disorders/blood , Blood Coagulation Factors , Blood Platelets/metabolism , Cytoplasmic Granules/metabolism , Globulins , Growth Substances , Platelet Factor 4 , Adenosine Diphosphate/metabolism , Adenosine Triphosphate/metabolism , Adult , Blood Coagulation Disorders/genetics , Calcium/metabolism , Female , Fibrinogen/metabolism , Genetic Variation , Heparin/metabolism , Humans , Male , Middle Aged , Mitochondria , Serotonin/metabolismABSTRACT
This is a study of a 34 year old woman with a moderate to severe bleeding disorder in whom impaired platelet procoagulant activity (PPA) was found by several methods, including tests of factor 3 availability (PF-3a), prothrombin consumption and contact activation. No deficiencies of platelet adhesion, aggregation, secretion, metabolism or granule-bound substances were detectable. Under adequate platelet coverage, this woman underwent two surgical procedures without difficulty. These findings demonstrate the role of PPA in hemostasis and indicate that a defect in PPA can be an isolated occurrence. The abnormalities in PF-3a found in this patient could be due to the diminished number of factor V binding sites, resulting in impaired factor Xa binding, found in separate studies by Majerus et al.
