Ultrastructural observation of the surface coat of human platelets aggregated by polylysine and dextran
スポンサーリンク
概要
- 論文の詳細を見る
Flocculation of colloid particles suspended in macromolecular solution has been attributed to macromolecular bridging of the particle surfaces. In recent years, the effect of cationic polymers such as polylysine on platelets has been studied by various investigators. It was suggested that these materials probably reduced the negative surface charge and formed bridges between the adjacent platelet membranes. Little work, however, has been done on the structure of intercellular space of the aggregated platelets induced by cationic polymers.In the present study, the surface coat of human platelets was stained with positively charged colloidal Thorotrast particles and ru thenium red to elucidate the mechanism of platelet aggregation by macromolecule. The aggregability of platelets and intercellular relationship in aggregated platelets by positively charged macromolecule, polylysine, and neutral macromolecule, dextran, with different molecular sizes and at various concentration was studied.Polylysines (Mw. 15, 000, 23, 000, 180, 000) could induce the aggregation in low concentration but relatively high concentration was needed in the case of dextran (Mw. 40, 000, 250, 000, 2, 000, 000). Both polylysine and dextran could easily induce the aggregation when larger molecular-weight one was used at the same concentration.In the dextran induced aggregation, Thorotrast particles on the cell surface of platelets in the aggregate did not decrease significantly. On the other hand, the surface membrane of aggregated platelets induced by polylysine was essentially devoid of bound particles. These findings suggested at the ultrastructural level that positivly charged polylysine induced aggregation by reducing the negative surface charge of platelets and explained the relatively lower concentration needed for polylysine to induce aggegation than neutral macromolecule, dextran. It seems probable that these macromolecules from bridges between the platelets. The average distance between plasma membranes of the aggregated platelets, however, did not vary with the degrees of polymerization of these macromolecules.In this respect, platelet aggregation differs from the aggregation of red cell by dextran in which widening of the intercellular space was observed with an increase in dextran molecular size (Chien, S. and Jan, K-M., 1973). The discrepancy between platelet and red cell aggregation may be due to the functional specificity of platelets that undergo "release reaction" and secondary aggregation. In the initial stage of platelet aggregation, these macromolecules probably play an important role by their bridging force in bringing about the cell to cell contact. In the event of release reaction or secondary aggregation, these primary aggregate may be more compact in which the intercellular space has the same distance as that of ADP induced aggregation.
- 一般社団法人 日本血栓止血学会の論文
一般社団法人 日本血栓止血学会 | 論文
- 日本人のＡＤＡＭＴＳ１３
- Infection of specific strains of Streptococcus mutans exacerbated intracerebral hemorrhage
- Transcriptional regulation of megakaryopoiesis and thrombopoiesis
- 新規血小板活性化受容体ＣＬＥＣ－２ その発見から今後の展望まで:その発見から今後の展望まで
- １．臨床血栓止血学オーバービュー