Heterogeneous abnormalities of platelet dense granule ultrastructure in 20 patients with congenital storage pool deficiency

Abstract

Studies on platelet dense granule structure were carried out in 20 patients with various types of congenital storage pool deficiency (SPD), including 15 with specific deficiencies of dense granules and dense granule substances (delta-SPD), and five with combined deficiencies of dense and alpha-granules (alpha delta-SPD). Dense granules were identified by their high affinity for uranyl ions (uranaffin reaction), by their ability to accumulate the fluorescent dye mepacrine, and by their inherent electron opacity on unfixed, unstained whole mount preparations. By all these methods, dense granules were markedly decreased in seven albino patients with the Hermansky-Pudlak syndrome (HPS) variant of delta-SPD. These findings suggest that the basic defect in these patients is a specific abnormality in organelle development which prevents the formation of an intact granule structure, a quantitative abnormality which may differ from that in animals with related pigment disorders. In contrast, eight non-albino patients with delta-SPD had, on average, only a slightly reduced number of uranaffin-positive and mepacrine-positive granules, but a shift in uranaffin-granule distribution towards those lacking a dense core ('empty granules'), suggesting a more qualitative type of dense granule defect. These results are consistent with previous evidence suggesting a decreased uptake of ATP across the granule membrane in delta-SPD. In addition, on whole mounts, these patients' platelets contained substantial numbers of electron dense chains and clusters which contained P and Ca, but with a P/Ca ratio less than that of typical dense granules, and which were retained, along with a larger amount of ATP, after thrombin treatment of the platelets. The various findings in these patients raise the possibility that these structures may represent microvesicles, derived from the Golgi apparatus, which provide a transport mechanism for concentrating adenine nucleotides and calcium in dense granules and which is impaired in some patients with SPD. Additional defects may account for the more extensive granule abnormalities observed in alpha delta-SPD.

Diagnostic utility of light transmission platelet aggregometry: results from a prospective study of individuals referred for bleeding disorder assessments

“…Responses to epinephrine were not considered for diagnoses. All patients were tested for platelet dense granule deficiency by electron microscopy, as described [13] (RI, 5.6-9.0 dense granules per platelet; derived from non-parametric analysis of 124 tests, on 33 healthy controls, to establish 95% confidence intervals [CI]). Some were tested for platelet secretion defects by a lumiaggregometer assay for platelet ATP release with minor modifications of procedures recommended by the instrument manufacturer (Chrono-Log Corporation, Haverston, PA, USA) using: 400 lL PRP (250 · 10 9 platelets L )1…”

The regulation of platelet-dense granules by Rab27a in the ashen mouse, a model of Hermansky-Pudlak and Griscelli syndromes, is granule-specific and dependent on genetic background

“…Other mutations that cause abnormalities of alpha granule content and/or function have been described in patients with gray platelet syndrome, 21 alpha/delta storage pool deficiency, 57 and the Wistar Furth rat. 58 However, the molecular bases of these inherited syndromes remain unknown.…”

δ-Storage pool disease: a pitfall in the forensic investigation of sudden anal blood loss in children: a case report

“…Several types of δ-SPD have already been identified, associated with both acquired clinical conditions and congenital syndromes, e.g. ChediakHigashi syndrome [10,12,13,16].…”

“…Complementary, for example, flow cytometry of mepacrine-treated platelets is also possible [17,19]. However, as dense granules are inherently electron opaque probably due to their high-calcium content, they can readily be examined by electron microscopy [13]. This allows not only quantification of the number of dense granules but also evaluation of their morphology [16].…”

“…Dense granules were originally identified as storage organelles in platelets of mammalian species, containing in humans, serotonin, calcium, adenosine diphosphate (ADP), adenosine triphosphate and pyrophosphate [10][11][12][13]. When platelets are activated, these granules release the content through the canalicular system [14].…”