Decreased content and surface expression of alpha-granule membrane protein GMP-140 in one of two types of platelet alpha delta storage pool deficiency.

Abstract

To determine whether a-granule membranes are present in platelets of patients with storage pool deficiencies of both alpha and dense granules (ab-SPD), we examined the content and surface expression of the a-granule membrane protein GMP-140 in one patient (J.C.) with a severe a-granule deficiency and in three members of a family (family C) with milder a-granule deficiencies. Surface expression of GMP-140 in stimulated platelets, assessed by flow cytometric measurements of the binding of two anti-GMP-140 monoclonal antibodies, was 24-38% of normal values in platelets from patient J.C., vs. 60-95% of normal values in family C. Total platelet content of GMP-140, determined in platelet lysates by antigen-capture ELISA, was 49% of normal in patient J.C., but normal in the members of family C. Platelets of patient J.C. were found to be heterogeneous with respect to GMP-140 content and surface expression by both flow cytometry and immunogold electron microscopy. Approximately 80% of her platelets expressed little or no GMP-140 after stimulation, whereas the remaining 20% expressed normal amounts of GMP-140 and showed extensive immunogold labeling of typical a-granules and clear vacuoles. No such heterogeneity was found in platelets from family C. These findings in the severe ab-SPD patient are in clear contrast to the observations of normal GMP-140 content in the three other ab-SPD patients, and in patients with the gray platelet syndrome, reported previously by others. These results illustrate the phenotypic heterogeneity of a-granule deficiencies in human platelets, and suggest that a defect in granule formation in the megakaryocytes may account for the a-granule defect in at least one form of ab-SPD. (J. Clin. Invest. 1991. 87:919-929.)

In vitro analyses of known and novel RUNX1/AML1 mutations in dominant familial platelet disorder with predisposition to acute myelogenous leukemia: implications for mechanisms of pathogenesis

“…28,29 The platelet counts in this family are at or slightly below the lower limit of normal. 26,27 Two members of the family developed AML, and another was reported to have died of leukemia.…”

“…Pedigree 3 consists of 15 affected individuals from 4 generations of a family with a bleeding disorder characterized by impaired platelet aggregation associated with decreased numbers and contents of both platelet-dense and ␣ granules 26,27 as well as a unique platelet phospholipid defect and decreased ␣-2 adrenergic receptors. 28,29 The platelet counts in this family are at or slightly below the lower limit of normal. 26,27 Two members of the family developed AML, and another was reported to have died of leukemia.…”

RUNX1 deficiency (familial platelet disorder with predisposition to myeloid leukemia, FPDMM)

“…Dense-granule storage pool deficiency represents the most frequent abnormality [8], although other defects, such as partial alpha-granule deficiency, impaired activation of the fibrinogen receptor, GPIIbIIIa, and defective platelet spreading have also been described in some patients [23][24][25]. The bleeding diathesis is variable within and among families.…”

Gray platelet syndrome: natural history of a large patient cohort and locus assignment to chromosome 3p

“…Immediately after collection, citrated whole blood (450 mL) was mixed for 5 minutes with either 50 mL phosphate-buffered saline, 50 mL 200mM lyophilized adenosine-5Ј-diphosphate solution (Bio/Data Corp), or 50 mL 100mM thrombin receptor-activating peptide from Biosearch and further processed and evaluated as described. 17,28 Thrombin stimulation of platelets in citrated venous whole blood and labeling with anti-CD62P or anti-TSP-1 antibodies was performed as described. 38 …”

“…25,27 Studies of granule membrane-specific proteins have shown that platelets and megakaryocytes of GPS patients have rudimentary ␣-granule precursors. 7,28,29 Therefore, the basic defect in GPS is thought to be the inability of megakaryocytes to pack endogeneously synthesized secretory proteins into developing ␣-granules.…”