title: Relationship between mepacrine-labelled dense body number, platelet capacity to accumulate 14C-5-HT and platelet density in the Bernard-Soulier and Hermansky-Pudlak syndromes.
abstract: We have used the mepacrine-labelling procedure to measure the dense body (serotonin storage organelle) content of the platelets of 2 hereditary disorders where abnormalities in dense body number were suspected. The platelets were incubated with mepacrine and examined by fluorescence microscopy. A mean number of 5.4 +/- 0.8 (SD) dense bodies per platelet was calculated from the data obtained using platelets isolated from 40 normal human subjects. In contrast the platelets of 2 patients with the Bernard-Soulier syndrome contained an average of 14 and 17 labelled granules. This increase was associated with a much greater capacity of the platelets to accumulate 14C-5-HT. The opposite result was obtained using the platelets from 2 patients with the Hermansky-Pudlak syndrome which contained few granules labelled by mepacrine and took up less 14C-5-HT than normal human platelets. Centrifugation of the patients' platelets on discontinuous sucrose gradients showed that the platelets of the 2 Bernard-Soulier patients were much denser than normal whereas a high proportion of low density platelets was observed in the Hermansky-Pudlak syndrome. These results further define the platelet abnormalities in the two syndromes and suggest that dense body number may be one of the factors governing platelet density.
mesh_terms: D000293:Adolescent; D000328:Adult; D001791:Blood Platelet Disorders / Q000097:blood*; D001792:Blood Platelets / Q000145:classification / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002469:Cell Separation; D002648:Child; D003594:Cytoplasmic Granules / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D011796:Quinacrine / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D013577:Syndrome
chemical_list: D002250:Carbon Radioisotopes; D012701:Serotonin; D011796:Quinacrine